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Sample records for bi2fecro6 multiferroic thin

  1. Multiferroic oxide thin films and heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Chengliang, E-mail: cllu@mail.hust.edu.cn, E-mail: Tao.Wu@kaust.edu.sa [School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Hu, Weijin; Wu, Tom, E-mail: cllu@mail.hust.edu.cn, E-mail: Tao.Wu@kaust.edu.sa [Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia); Tian, Yufeng [School of Physics, Shandong University, Jinan 250100 (China)

    2015-06-15

    Multiferroic materials promise a tantalizing perspective of novel applications in next-generation electronic, memory, and energy harvesting technologies, and at the same time they also represent a grand scientific challenge on understanding complex solid state systems with strong correlations between multiple degrees of freedom. In this review, we highlight the opportunities and obstacles in growing multiferroic thin films with chemical and structural integrity and integrating them in functional devices. Besides the magnetoelectric effect, multiferroics exhibit excellent resistant switching and photovoltaic properties, and there are plenty opportunities for them to integrate with other ferromagnetic and superconducting materials. The challenges include, but not limited, defect-related leakage in thin films, weak magnetism, and poor control on interface coupling. Although our focuses are Bi-based perovskites and rare earth manganites, the insights are also applicable to other multiferroic materials. We will also review some examples of multiferroic applications in spintronics, memory, and photovoltaic devices.

  2. Multiferroic oxide thin films and heterostructures

    KAUST Repository

    Lu, Chengliang

    2015-05-26

    Multiferroic materials promise a tantalizing perspective of novel applications in next-generation electronic, memory, and energy harvesting technologies, and at the same time they also represent a grand scientific challenge on understanding complex solid state systems with strong correlations between multiple degrees of freedom. In this review, we highlight the opportunities and obstacles in growing multiferroic thin films with chemical and structural integrity and integrating them in functional devices. Besides the magnetoelectric effect, multiferroics exhibit excellent resistant switching and photovoltaic properties, and there are plenty opportunities for them to integrate with other ferromagnetic and superconducting materials. The challenges include, but not limited, defect-related leakage in thin films, weak magnetism, and poor control on interface coupling. Although our focuses are Bi-based perovskites and rare earth manganites, the insights are also applicable to other multiferroic materials. We will also review some examples of multiferroic applications in spintronics, memory, and photovoltaic devices.

  3. Growth and characterisation of Bi-based multiferroic thin films

    OpenAIRE

    Langenberg Pérez, Eric

    2013-01-01

    Multiferroic materials, in which both ferroelectric and (anti)ferromagnetic orders coexist in the same phase, have received much interest in the last few years. The possibility of these two ferroic orders being coupled allows new functionalities in these materials as controlling the magnetisation by an electric field or, conversely, controlling the polarisation by a magnetic field. The fulfilment of this magnetoelectric coupling is not only interesting in terms of fundamental research but it ...

  4. Dynamic response in a finite size composite multiferroic thin film

    Science.gov (United States)

    Wang, Zidong; Grimson, Malcolm J.

    2016-03-01

    Composite multiferroics, heterostructures of ferromagnetic and ferroelectric materials, are characterized by a remarkable magnetoelectric effect at the interface. Previous work has supported the ferromagnetic structure with magnetic spins and the ferroelectric with pseudospins which act as electric dipoles in a microscopic model, coupled with a magnetoelectric interaction [Wang and Grimson, J. Appl. Phys. 118, 124109 (2015)]. In this work, by solving the stochastic Landau-Lifshitz-Gilbert equation, the electric-field-induced magnetization switching in a twisted boundary condition has been studied, and a behavior of domain wall in the ferromagnetic structure is discussed.

  5. Phenomenological theory of 1-3 type multiferroic composite thin film: thickness effect

    International Nuclear Information System (INIS)

    The effect of thickness on the para-ferro-phase transition temperatures, the spontaneous polarization and magnetization and hysteresis loops of 1-3 type multiferroic composite thin films was studied in the framework of Landau phenomenological theory. We took into account the electrostrictive and magnetostrictive effects, misfit strains induced from the interfaces of ferroelectric/ferromagnetic portions and film/substrate. Butterfly loops under external fields were also simulated.

  6. Phenomenological theory of 1-3 type multiferroic composite thin film: thickness effect

    Energy Technology Data Exchange (ETDEWEB)

    Lu Xiaoyan; Wang Biao; Zheng Yue [School of Astronautics, Harbin Institute of Technology, Harbin 150001 (China); Ryba, Earle [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, 16802 (United States)], E-mail: wangbiao@mail.sysu.edu.cn

    2009-01-07

    The effect of thickness on the para-ferro-phase transition temperatures, the spontaneous polarization and magnetization and hysteresis loops of 1-3 type multiferroic composite thin films was studied in the framework of Landau phenomenological theory. We took into account the electrostrictive and magnetostrictive effects, misfit strains induced from the interfaces of ferroelectric/ferromagnetic portions and film/substrate. Butterfly loops under external fields were also simulated.

  7. Critical phase transition temperatures of 1-3 type multiferroic composite thin films

    International Nuclear Information System (INIS)

    The critical phase transition temperatures of the ferroelectric (FE) phase and the ferromagnetic (FM) phase in epitaxial 1-3 type multiferroic thin films were obtained based on the thermodynamic model. Analytic expressions of the para-ferro transition temperatures were derived as functions of the volume fraction of the FM phase by considering the effect of the coupled elastic stresses arising from the FE/FM and the film/substrate interfaces. Our results show that the critical temperatures are significantly affected by the induced stresses and can be controlled by adjusting the volume fractions of the different phases within the thin film

  8. Critical phase transition temperatures of 1-3 type multiferroic composite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Lu Xiaoyan [Electro-Optics Technology Center, Harbin Institute of Technology, Harbin 150001 (China); Wang Biao [Electro-Optics Technology Center, Harbin Institute of Technology, Harbin 150001 (China); Zheng Yue [Electro-Optics Technology Center, Harbin Institute of Technology, Harbin 150001 (China); Ryba, Earle [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2007-03-21

    The critical phase transition temperatures of the ferroelectric (FE) phase and the ferromagnetic (FM) phase in epitaxial 1-3 type multiferroic thin films were obtained based on the thermodynamic model. Analytic expressions of the para-ferro transition temperatures were derived as functions of the volume fraction of the FM phase by considering the effect of the coupled elastic stresses arising from the FE/FM and the film/substrate interfaces. Our results show that the critical temperatures are significantly affected by the induced stresses and can be controlled by adjusting the volume fractions of the different phases within the thin film.

  9. Application of a generalized matrix averaging method for the calculation of the effective properties of thin multiferroic layers

    International Nuclear Information System (INIS)

    It is proposed to use a generalized matrix averaging (GMA) method for calculating the parameters of an effective medium with physical properties equivalent to those of a set of thin multiferroic layers. This approach obviates the need to solve a complex system of magnetoelectroelasticity equations. The required effective characteristics of a system of multiferroic layers are obtained using only operations with matrices, which significantly simplifies calculations and allows multilayer systems to be described. The proposed approach is applicable to thin-layer systems, in which the total thickness is much less than the system length, radius of curvature, and wavelengths of waves that can propagate in the system (long-wave approximation). Using the GMA method, it is also possible to obtain the effective characteristics of a periodic structure with each period comprising a number of thin multiferroic layers

  10. Application of a generalized matrix averaging method for the calculation of the effective properties of thin multiferroic layers

    Energy Technology Data Exchange (ETDEWEB)

    Starkov, A. S. [St. Petersburg National Research University of Information Technologies, Mechanics and Optics, Institute of Refrigeration and Biotechnology (Russian Federation); Starkov, I. A., E-mail: ferroelectrics@ya.ru [Brno University of Technology, SIX Research Centre (Czech Republic)

    2014-11-15

    It is proposed to use a generalized matrix averaging (GMA) method for calculating the parameters of an effective medium with physical properties equivalent to those of a set of thin multiferroic layers. This approach obviates the need to solve a complex system of magnetoelectroelasticity equations. The required effective characteristics of a system of multiferroic layers are obtained using only operations with matrices, which significantly simplifies calculations and allows multilayer systems to be described. The proposed approach is applicable to thin-layer systems, in which the total thickness is much less than the system length, radius of curvature, and wavelengths of waves that can propagate in the system (long-wave approximation). Using the GMA method, it is also possible to obtain the effective characteristics of a periodic structure with each period comprising a number of thin multiferroic layers.

  11. Fabrication of multiferroic GdMnO3 thin film by pulsed laser deposition technique

    Science.gov (United States)

    Negi, Puneet; Agrawal, H. M.; Srivastava, R. C.; Asokan, K.

    2012-06-01

    Here, we report the fabrication of GdMnO3 multiferroic thin film on SrTiO3 (110) substrate by pulsed laser deposition (PLD) technique. The target sample was synthesized using modified solgel route. The thickness of the film observed by Talystep profilometer, is about 200 nm. X-ray diffraction and Raman spectroscopic techniques were used to investigate the structure of the target as well as of the film. The surface topography of the film was investigated by atomic force microscopy.

  12. Synthesis of multiferroic Er-Fe-O thin films by atomic layer and chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Mantovan, R., E-mail: roberto.mantovan@mdm.imm.cnr.it; Vangelista, S.; Wiemer, C.; Lamperti, A.; Tallarida, G. [Laboratorio MDM IMM-CNR, I-20864 Agrate Brianza (MB) (Italy); Chikoidze, E.; Dumont, Y. [GEMaC, Université de Versailles St. Quentin en Yvelines-CNRS, Versailles (France); Fanciulli, M. [Laboratorio MDM IMM-CNR, I-20864 Agrate Brianza (MB) (Italy); Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, Milano (Italy)

    2014-05-07

    R-Fe-O (R = rare earth) compounds have recently attracted high interest as potential new multiferroic materials. Here, we report a method based on the solid-state reaction between Er{sub 2}O{sub 3} and Fe layers, respectively grown by atomic layer deposition and chemical vapor deposition, to synthesize Er-Fe-O thin films. The reaction is induced by thermal annealing and evolution of the formed phases is followed by in situ grazing incidence X-ray diffraction. Dominant ErFeO{sub 3} and ErFe{sub 2}O{sub 4} phases develop following subsequent thermal annealing processes at 850 °C in air and N{sub 2}. Structural, chemical, and morphological characterization of the layers are conducted through X-ray diffraction and reflectivity, time-of-flight secondary ion-mass spectrometry, and atomic force microscopy. Magnetic properties are evaluated by magnetic force microscopy, conversion electron Mössbauer spectroscopy, and vibrating sample magnetometer, being consistent with the presence of the phases identified by X-ray diffraction. Our results constitute a first step toward the use of cost-effective chemical methods for the synthesis of this class of multiferroic thin films.

  13. Sputter deposited Terfenol-D thin films for multiferroic applications

    Directory of Open Access Journals (Sweden)

    K. P. Mohanchandra

    2015-09-01

    Full Text Available In this paper, we study the sputter deposition and crystallization process to produce high quality Terfenol-D thin film (100 nm with surface roughness below 1.5 nm. The Terfenol-D thin film was produced using DC magnetron sputtering technique with various sputtering parameters and two different crystallization methods, i.e. substrate heating and post-annealing. Several characterization techniques including WDS, XRD, TEM, AFM, SQUID and MOKE were used to determine the physical and magnetic properties of the Terfenol-D films. TEM studies reveal that the film deposited on the heated substrate has large grains grown along the film thickness producing undesirable surface roughness while the film crystallized by post-annealing method shows uniformly distributed small grains producing a smooth surface. The Terfenol-D film was also deposited onto (011 cut PMN-PT single crystal substrate. With the application of an electric field the film exhibited a 1553 Oe change in coercivity with an estimated saturation magnetostriction of λs = 910 x 10−6.

  14. Sputter deposited Terfenol-D thin films for multiferroic applications

    Science.gov (United States)

    Mohanchandra, K. P.; Prikhodko, S. V.; Wetzlar, K. P.; Sun, W. Y.; Nordeen, P.; Carman, G. P.

    2015-09-01

    In this paper, we study the sputter deposition and crystallization process to produce high quality Terfenol-D thin film (100 nm) with surface roughness below 1.5 nm. The Terfenol-D thin film was produced using DC magnetron sputtering technique with various sputtering parameters and two different crystallization methods, i.e. substrate heating and post-annealing. Several characterization techniques including WDS, XRD, TEM, AFM, SQUID and MOKE were used to determine the physical and magnetic properties of the Terfenol-D films. TEM studies reveal that the film deposited on the heated substrate has large grains grown along the film thickness producing undesirable surface roughness while the film crystallized by post-annealing method shows uniformly distributed small grains producing a smooth surface. The Terfenol-D film was also deposited onto (011) cut PMN-PT single crystal substrate. With the application of an electric field the film exhibited a 1553 Oe change in coercivity with an estimated saturation magnetostriction of λs = 910 x 10-6.

  15. Multiferroic properties of uniaxially compressed orthorhombic HoMnO3 thin films

    Science.gov (United States)

    Shimamoto, K.; Windsor, Y. W.; Hu, Y.; Ramakrishnan, M.; Alberca, A.; Bothschafter, E. M.; Rettig, L.; Lippert, Th.; Staub, U.; Schneider, C. W.

    2016-03-01

    Multiferroic properties of orthorhombic HoMnO3 (Pbnm space group) are significantly modified by epitaxial compressive strain along the a-axis. We are able to focus on the effect of strain solely along the a-axis by using an YAlO3 (010) substrate, which has only a small lattice mismatch with HoMnO3 along the other in-plane direction (the c-axis). Multiferroic properties of strained and relaxed HoMnO3 thin films are compared with those reported for bulk, and are found to differ widely. A relaxed film exhibits bulk-like properties such as ferroelectricity below 25 K and an incommensurate antiferromagnetic order below 39 K, with an ordering wave vector of (0 qb 0) with qb ≈ 0.41 at ˜10 K. A strained film becomes ferroelectric already at 37.5 K and has an incommensurate magnetic order with qb ≈ 0.49 at ˜10 K.

  16. Polarization-tuned diode behaviour in multiferroic BiFeO3 thin films

    KAUST Repository

    Yao, Yingbang

    2012-12-28

    Asymmetric rectifying I-V behaviour of multiferroic BiFeO3 (BFO) thin films grown on transparent ITO-coated glass was quantitatively studied as a function of ferroelectric polarization. Different polarized states were established by unipolar or bipolar poling with various applied electric fields. The effects of polarization relaxation and fatigue on the currents were also investigated. We found that the conduction currents and the associated rectifications were controlled by the amplitude and direction of the polarization. We clearly observed the linear dependence of the current on the polarization. It is suggested that the space-charge-limited conduction and the charge injection at the Schottky interface between the film and the electrodes dominate the current. The electrically controlled rectifying behaviour observed in this study may be useful in nonvolatile resistance memory devices or tunable diodes. © 2013 IOP Publishing Ltd.

  17. Double-perovskite multiferroic Bi2FeCrO6 polycrystalline thin film: The structural, multiferroic, and ferroelectric domain properties

    International Nuclear Information System (INIS)

    Highlights: ► Double perovskite multiferroic BFCO film was grown by PLD method. ► Domain evolution under external electric field was simulated by Monte-Carlo method. ► Better electrical, ferroelectric and magnetic properties were found in BFCO film. ► BFCO film may be a promising material for functional device application. -- Abstract: Double-perovskite Bi2FeCrO6 (BFCO) thin film has been deposited on Pt/Ti/SiO2/Si (1 0 0) substrate by pulsed laser deposition method. X-ray diffraction reveals that the BFCO film was polycrystalline and high purity. The surface morphology in BFCO film exhibits the dense and uniform grain. Interestingly, compared with BiFeO3 film, the BFCO film shows a better ferroelectric properties. Moreover, a well-defined magnetic hysteresis of the BFCO film indicates a ferromagnetic property at room temperature. The ferroelectric domain structure of polycrystalline BFCO film was investigated by piezoresponse force microscopy. Furthermore, the domain structure of polycrystalline BFCO film under an applied electric field was simulated by a Monte Carlo method. Those results suggest that the multiferroic BFCO double-perovskite thin film may be a promising functional material for the future device application

  18. Room temperature multiferroic properties of (Fex, Sr1−x)TiO3 thin films

    International Nuclear Information System (INIS)

    This letter reports the structural, dielectric, ferroelectric, and magnetic properties of Fe substituted SrTiO3 thin films in room temperature. The structural data obtained from x-ray diffraction indicates that (Fex,Sr1−x)TiO3, the so called FST, transforms from pseudocubic to tetragonal structures with increase of the Fe content in SrTiO3 thin films, featuring the ferroelectricity, while vibrating sample magnetometer measurements show magnetic hysteresis loops for the samples with low iron contents indicating their ferromagnetism. The characterized ferroelectricity and ferromagnetism confirms strong multiferroitism of the single phase FST thin films in room temperature. Also, an FST thin film metal-insulator-metal multiferroic capacitor has been fabricated and characterized in microwave frequencies between 10 MHz and 5 GHz. A capacitor based on Fe0.1Sr0.9TiO3 with a thickness of 260 nm shows a high electric tunability of 18.6% at 10 V and a maximum magnetodielectric value of 1.37% at 0.4 mT with a loss tangent of 0.021 at 1 GHz. This high tuning and low loss makes this material as a good candidate for frequency agile microwave devices such as tunable filters, phase shifters, and antennas.

  19. PREFACE: Multiferroics Multiferroics

    Science.gov (United States)

    Loidl, Alois; von Loehneysen, Hilbert; Kalvius, G. Michael

    2008-10-01

    earths, i.e., RMnO3 [6], RMn2O5 [7], or Ni3V2O8 [8] which are characterized by strong spin frustration due to competing exchange interactions. In fact, they reveal transitions into magnetic phases with complex non-collinear spin order, thereby breaking inversion symmetry and concomitantly inducing ferroelectricity. This renaissance of multiferroics was made possible because developments in sample growth and sample characterization allowed the production of high quality single crystals and thin films. In addition, computational methods helped to design new materials with outstanding properties. To explore the complex physics of multiferroics, outstanding laboratories with novel instrumentation and exceptional theoretical tools were involved. Most of the scientists responsible for this enormous revival in the synthesis, characterization, and modeling of these new classes of multiferroics have contributed to this special issue. Hence, it provides an impressive survey of the state of the art and documents key experiments in this area of condensed matter research: dielectric spectroscopy as a function of temperature and external magnetic field, neutron-scattering experiments to unravel the complex magnetic phase diagrams including spin order and magnetic excitations and also to explore possible induced lattice deformations, as well as optical experiments to search for new classes of excitations, like electromagnons. In addition, intense modeling of the underlying physics of multiferroics and fascinating theoretical concepts—these issues are all documented in this issue on multiferroics, as well as possible applications in modern optics or in spintronics. Furthermore, new routes to multiferroicity are also tackled, like charge order or electronic ferroelectricity as prototypical and important examples. This special issue provides an inspiring overview of the ongoing research in the field of magnetoelectric effects, multiferroicity and ferrotoroidicity. We hope it will

  20. Multiferroic BiFeO{sub 3} thin films: Structural and magnetic characterization

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Z. [Physics Department, Faculty of Science (Girls Branch), Al-Azhar University, Cairo (Egypt); Atta, A. [National Center for Radiation Research and Technology (NCRRT), Nasr City, Cairo (Egypt); Abbas, Y. [Physics Department, Faculty of Science, Suez Canal University, Ismailia (Egypt); Sedeek, K.; Adam, A.; Abdeltwab, E. [Physics Department, Faculty of Science (Girls Branch), Al-Azhar University, Cairo (Egypt)

    2015-02-27

    BiFeO{sub 3} (BFO) film has been deposited on indium tin oxide (ITO) substrate by a simple sol–gel spin-coating technique. The crystal phase composition, surface morphology, topography and magnetization measurements of the BFO thin film were investigated using grazing incidence X-ray diffraction (GIXRD), scanning electronic microscope (SEM), atomic force microscope and vibrating sample magnetometer, respectively. GIXRD analysis revealed that the film was fully crystallized and no impure phase was observed. Cross-section SEM results indicated that compact and homogeneous BFO thin film was deposited on ITO with a thickness of about 180 nm. Moreover, most of A and E-symmetry normal modes of R3c BFO were assigned by Raman spectroscopy. We report here that the pure phase BFO film shows ferromagnetism at room temperature with remarkably high saturation magnetization of 63 kA m{sup −1}. Our results are discussed mainly in correlation with the condition of processing technique and destruction of the spiral spin cycloid at interface layers and grain boundaries. - Highlights: • Multiferroic BiFeO{sub 3} (BFO) thin film was prepared by sol–gel spin-coating method. • BFO film w asdeposited on indium tin oxide substrate with a thickness of 180 nm. • The film exhibits pure rhombohedral perovskite structure. • High saturation magnetization was recorded for our film at room temperature.

  1. The evolution of multiferroics

    Science.gov (United States)

    Fiebig, Manfred; Lottermoser, Thomas; Meier, Dennis; Trassin, Morgan

    2016-08-01

    Materials with a coexistence of magnetic and ferroelectric order — multiferroics — provide an efficient route for the control of magnetism by electric fields. The study of multiferroics dates back to the 1950s, but in recent years, key discoveries in theory, synthesis and characterization techniques have led to a new surge of interest in these materials. Different mechanisms, such as lone-pair, geometric, charge-ordering and spin-driven effects, can support multiferroicity. The general focus of the field is now shifting into neighbouring research areas, as we discuss in this Review. Multiferroic thin-film heterostructures, device architectures, and domain and interface effects are explored. The violation of spatial and inversion symmetry in multiferroic materials is a key feature because it determines their properties. Other aspects, such as the non-equilibrium dynamics of multiferroics, are underrated and should be included in the topics that will define the future of the field.

  2. Theoretical study of the multiferroic properties in M-doped (M=Co, Cr, Mg) ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bahoosh, S.G. [Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Germany); Apostolov, A.T. [University of Architecture, Civil Engineering and Geodesy, Faculty of Hydrotechnics, Department of Physics, 1, Hristo Smirnenski Blvd., 1046 Sofia (Bulgaria); Apostolova, I.N. [University of Forestry, Faculty of Forest Industry, 10, Kl. Ohridsky Blvd., 1756 Sofia (Bulgaria); Trimper, S. [Institute of Physics, Martin-Luther-University, D-06099 Halle (Germany); Wesselinowa, Julia M. [University of Sofia, Department of Physics, Blvd. J. Bouchier 5, 1164 Sofia (Bulgaria)

    2015-01-01

    The origin of multiferroism is still an open problem in ZnO. We propose a microscopic model to clarify the occurrence of multiferroism in this material. Using Green's function technique we study the influence of ion doping and size effects on the magnetization and polarization of ZnO thin films. The calculations for magnetic Co- and Cr-ions are based on the s–d model, the transverse Ising model in terms of pseudo-spins and a biquadratic magnetoelectric coupling, whereas in case of nonmagnetic Mg-ions the model takes into account the Coulomb interaction and an indirect coupling between the pseudo-spins via the conduction electrons. We show that the magnetization M exhibits a maximum for a fixed concentration of the doping ions. Furthermore M increases with decreasing film thickness N. The polarization increases with increasing concentration of the dopant and decreasing N. The results are in good agreement with the experimental data. - Highlights: • The paper analyzes the multiferroic properties of doped ZnO thin films by a microscopic model. • The magnetization exhibits a maximum at a fixed doping concentration. • The polarization increases with growing dopant concentration. • The ferroelectric transition temperature is enhanced for increasing dopant concentration.

  3. Interfacial-strain-induced structural and polarization evolutions in epitaxial multiferroic BiFeO3 (001) thin films.

    Science.gov (United States)

    Guo, Haizhong; Zhao, Ruiqiang; Jin, Kui-Juan; Gu, Lin; Xiao, Dongdong; Yang, Zhenzhong; Li, Xiaolong; Wang, Le; He, Xu; Gu, Junxing; Wan, Qian; Wang, Can; Lu, Huibin; Ge, Chen; He, Meng; Yang, Guozhen

    2015-02-01

    Varying the film thickness is a precise route to tune the interfacial strain to manipulate the properties of the multiferroic materials. Here, to explore the effects of the interfacial strain on the properties of the multiferroic BiFeO3 films, we investigated thickness-dependent structural and polarization evolutions of the BiFeO3 films. The epitaxial growth with an atomic stacking sequence of BiO/TiO2 at the interface was confirmed by scanning transmission electron microscopy. Combining X-ray diffraction experiments and first-principles calculations, a thickness-dependent structural evolution was observed from a fully strained tetragonality to a partially relaxed one without any structural phase transition or rotated twins. The tetragonality (c/a) of the BiFeO3 films increases as the film thickness decreases, while the polarization is in contrast with this trend, and the size effect including the depolarization field plays a crucial role in this contradiction in thinner films. These findings offer an alternative strategy to manipulate structural and polarization properties by tuning the interfacial strain in epitaxial multiferroic thin films. PMID:25580936

  4. Ultrafast carrier dynamics and radiative recombination in multiferroic BiFeO3 single crystals and thin films

    Directory of Open Access Journals (Sweden)

    Taylor A. J.

    2013-03-01

    Full Text Available We report a detailed comparison of ultrafast carrier dynamics in single crystals and thin films of multiferroic BiFeO3 (BFO. Using degenerate femtosecond optical pump-probe spectroscopy, we find that the observed dynamics are qualitatively similar in both samples. After photoexcitation, electrons relax to the conduction band minimum through electron-phonon coupling, with subsequent carrier relaxation proceeding via various recombination pathways that extend to a nanosecond timescale. Subtle differences observed in our measurements indicate that BFO films have a higher band gap than single crystals. Overall, our results demonstrate that carrier relaxation in BFO is analogous to that in bulk semiconductors.

  5. The influence of Er, Ti co-doping on the multiferroic properties of BiFeO3 thin films

    Science.gov (United States)

    Ma, Yinina; Xing, Wenyu; Chen, Jieyu; Bai, Yulong; Zhao, Shifeng; Zhang, Hao

    2016-02-01

    The pure and Er, Ti co-doped BiFeO3 thin films were prepared by chemistry solution deposition. Enhanced ferroelectric and ferromagnetic properties were obtained, which is mainly attributed to that the effect of co-doping Er and Ti leads to the drastic crystal structural transformation from rhombohedral phase to orthorhombic phase. Thus crystal structural transformation not only changes the switching behavior of the polarization path to improve the ferroelectric polarization, but also suppresses the original spiral spin structure to release the locked magnetization. At the same time, the leakage current density is decreased after doping Er3+ and Ti4+, which results from that the crystal structural transformation changes the leakage current mechanism. The present work provides an available way on improving the multiferroic properties of BiFeO3 thin films.

  6. Room temperature magnetoelectric coupling in BaTi1-xCrxO3 multiferroic thin films

    Science.gov (United States)

    Sundararaj, Anuraj; Chandrasekaran, Gopalakrishnan; Therese, Helen Annal; Annamalai, Karthigeyan

    2016-01-01

    We report on room temperature (RT) magnetoelectric coupling in tetragonal BaTi1-xCrxO3 thin film multiferroics (BTCO) sputter deposited on (100) SrTiO3 (where x = 0.005, 0.01, 0.02, and 0.03). As-deposited thin films are vacuum annealed by electron beam rapid thermal annealing technique. 50 nm thick BTCO with "x = 0.01" shows RT ferromagnetic and ferroelectric response with saturation magnetic moment of 1120 emu/cc and polarization of 14.7 microcoulomb/cm2. Piezoresponse/magnetic force microscope images shows RT magnetoelectric coupling in BTCO with "x = 0.01," which is confirmed using magnetocapacitance measurement where an increase in capacitance from 17.5 pF to 18.4 pF is observed with an applied magnetic field.

  7. Magnetoelectric coupling in multiferroic heterostructure of rf-sputtered Ni-Mn-Ga thin film on PMN-PT

    Science.gov (United States)

    Teferi, M. Y.; Amaral, V. S.; Lounrenco, A. C.; Das, S.; Amaral, J. S.; Karpinsky, D. V.; Soares, N.; Sobolev, N. A.; Kholkin, A. L.; Tavares, P. B.

    2012-06-01

    In this paper, we report a preparation of multiferroic heterostructure from thin film of Ni-Mn-Ga (NMG) alloy and lead magnesium niobate-lead titanate (PMN-PT) with effective magnetoelectric (ME) coupling between the film as ferromagnetic material and PMN-PT as piezoelectric material. The heterostructure was prepared by relatively low temperature (400 °C) deposition of the film on single crystal of piezoelectric PMN-PT substrate using rf magnetron co-sputtering of Ni50Mn50 and Ni50Ga50 targets. Magnetic measurements by Superconducting Quantum Interference Design (SQIUD) Magnetometer and Vibrating Sample Magnetometer (VSM) on the film revealed that the film is in ferromagnetically ordered martensitic state at room temperature with saturation magnetization of ˜240 emu/cm3 and Curie temperature of ˜337 K. Piezoresponse force microscopy (PFM) measurement done at room temperature on the substrate showed the presence of expected hysteresis loop confirming the stability of the piezoelectric state of the substrate after deposition. Room temperature ME voltage coefficient (αME) of the heterostructure was measured as a function of applied bias dc magnetic field in Longitudinal-Transverse (L-T) ME coupling mode by lock-in technique. A maximum ME coefficient αME of 3.02 mV/cm Oe was measured for multiferroic NMG/PMN-PT heterostructure which demonstrates that there is ME coupling between the film as ferromagnetic material and PMN-PT as piezoelectric material.

  8. Grain size and stoichiometry control over RF-sputtered multiferroic BiFeO3 thin films on silicon substrates

    International Nuclear Information System (INIS)

    This work reports the morphological and chemical characterization of multiferroic BiFeO3 polycrystalline thin films grown on Si(111) by RF-sputtering. Results are shown for a large set of samples and a wide array of experimental techniques, including imaging (atomic/piezoresponse force microscopy) and spectroscopic (μ-Raman, X-ray photoemission, X-ray diffraction) probes. Through growth and post-growth annealing treatment, a fine control over stoichiometry, grain size, grain orientation, crystal order and surface roughness is achieved. In particular, the grain size can be tailored from nanocrystals to large micrometric plates as a function of the annealing temperature. For the optimal stoichiometric sample, an additional X-ray absorption and magnetic circular dichroism analysis has been carried out, which provides high quality spectra comparable with epitaxial films and further proves the expected strong local antiferromagnetic order. - Highlights: • We show the growth of polycristalline multiferroic BiFeO3 on Si(111) by RF-sputtering. • Multi-technique (AFM/PFM,XPS,XRD,XAS,XMCD,Raman) characterization is given. • Crystal size, homogeneity and chemistry are tailored by growth or post-growth annealing. • In optimal conditions, piezoelectricity, ferroelectricity and magnetism are found

  9. Investigation on (Sr,Co)Bi2Nb2O9 thin films: A lead-free room temperature multiferroics

    International Nuclear Information System (INIS)

    Novel room temperature single phase multiferroic 10% Co doped SrBi2Nb2O9 (SCBN) thin films were fabricated on Pt/Ti/SiO2/Si(100) substrate by pulse laser deposition. The surface morphology indicates homogeneous grains with average grain size and surface roughness of ∝40-130 nm and 6 nm, respectively. High dielectric constant, low dielectric loss <2-5%, negligible frequency independent conductivity, moderate polarization, frequency dependent coercive field, and weak saturation magnetization were observed. The change in the shape of magnetic hysteresis and values of coercive field along in-plane and out-of-plane M-H hysteresis indicates a magnetic anisotropy. The presence of magnetic moments and electric dipole in the same plane suggest mutual cooperation between electric and magnetic ordering on the mesoscopic and microscopic scale. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Bundles of polytwins as meta-elastic domains in the thin polycrystalline simple multi-ferroic system PZT

    International Nuclear Information System (INIS)

    We used enhanced piezo-response force microscopy (E-PFM) to investigate both ferroelastic and ferroelectric nanodomains in thin films of the simple multi-ferroic system PbZr0.3Ti0.7O3 (PZT). We show how the grains are organized into a new type of elastic domain bundles of the well-known periodic elastic twins. Here we present these bundle domains and discuss their stability and origin. Moreover, we show that they can arrange in such a way as to release strain in a more effective way than simple twinning. Finally, we show that these bundle domains can arrange to form the macroscopic ferroelectric domains that constitute the basis of ferroelectric-based memory devices.

  11. Magnetoelectric coupling in multiferroic heterostructure of rf-sputtered Ni-Mn-Ga thin film on PMN-PT

    Energy Technology Data Exchange (ETDEWEB)

    Teferi, M.Y., E-mail: mandefero2002@yahoo.com [Departamento de Fisica, Universidade de Aveiro, 3810-193 Aveiro (Portugal); CICECO, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Amaral, V.S.; Lounrenco, A.C.; Das, S. [Departamento de Fisica, Universidade de Aveiro, 3810-193 Aveiro (Portugal); CICECO, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Amaral, J.S. [Departamento de Fisica, Universidade de Aveiro, 3810-193 Aveiro (Portugal); CICECO, Universidade de Aveiro, 3810-193 Aveiro (Portugal); IFIMUP-IN and Departamento de Fisica e Astronomia da Faculdade de Ciencias da Universidade do Porto, 4169-007 Porto (Portugal); Karpinsky, D.V. [CICECO, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Departamento de Engenharia Ceramica e do Vidro, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Soares, N. [Departamento de Fisica, Universidade de Aveiro, 3810-193 Aveiro (Portugal); CICECO, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Sobolev, N.A. [Departamento de Fisica, Universidade de Aveiro, 3810-193 Aveiro (Portugal); I3N, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Kholkin, A.L. [CICECO, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Departamento de Engenharia Ceramica e do Vidro, Universidade de Aveiro, 3810-193 Aveiro (Portugal); Tavares, P.B. [Centro de Quimica, Universidade de Tras-os-Montes e Alto Douro, 5001-801 Vila Real (Portugal)

    2012-06-15

    In this paper, we report a preparation of multiferroic heterostructure from thin film of Ni-Mn-Ga (NMG) alloy and lead magnesium niobate-lead titanate (PMN-PT) with effective magnetoelectric (ME) coupling between the film as ferromagnetic material and PMN-PT as piezoelectric material. The heterostructure was prepared by relatively low temperature (400 Degree-Sign C) deposition of the film on single crystal of piezoelectric PMN-PT substrate using rf magnetron co-sputtering of Ni{sub 50}Mn{sub 50} and Ni{sub 50}Ga{sub 50} targets. Magnetic measurements by Superconducting Quantum Interference Design (SQIUD) Magnetometer and Vibrating Sample Magnetometer (VSM) on the film revealed that the film is in ferromagnetically ordered martensitic state at room temperature with saturation magnetization of {approx}240 emu/cm{sup 3} and Curie temperature of {approx}337 K. Piezoresponse force microscopy (PFM) measurement done at room temperature on the substrate showed the presence of expected hysteresis loop confirming the stability of the piezoelectric state of the substrate after deposition. Room temperature ME voltage coefficient ({alpha}{sub ME}) of the heterostructure was measured as a function of applied bias dc magnetic field in Longitudinal-Transverse (L-T) ME coupling mode by lock-in technique. A maximum ME coefficient {alpha}{sub ME} of 3.02 mV/cm Oe was measured for multiferroic NMG/PMN-PT heterostructure which demonstrates that there is ME coupling between the film as ferromagnetic material and PMN-PT as piezoelectric material. - Highlights: Black-Right-Pointing-Pointer Multiferroic NMG/PMN-PT heterostructure prepared by depositing NMG alloy thin film on PMN-PT substrate. Black-Right-Pointing-Pointer The film is in ferromagnetically ordered martensite state at room temperature. Black-Right-Pointing-Pointer The substrate maintains its piezoelectric state after deposition. Black-Right-Pointing-Pointer The heterostructure exhibits ME effect with maximum of {alpha}{sub ME

  12. Origin of lowered magnetic moments in epitaxially strained thin films of multiferroic Bi2FeCrO6

    Science.gov (United States)

    Rout, Paresh C.; Putatunda, Aditya; Srinivasan, Varadharajan

    2016-03-01

    We have investigated the effect of epitaxial strain on the magnetic properties and B -site cation ordering in multiferroic Bi2FeCrO6 (001) thin films using a density-functional theory approach. We find that in thin films with rock-salt ordering of Fe and Cr the ground state is characterized by C-type antiferromagnetic (AFM) order. This is in contrast to the bulk form of the material, which was predicted to be a ferrimagnet with G-type AFM order. Furthermore, the cation-ordered thin films undergo a transition with epitaxial strain from C- to A-type AFM order. Other magnetic orders appear as thermally accessible excited states. We also find that B -site cation-disordered structures are more stable in coherent epitaxial strains, thereby explaining the lowered magnetic moments observed in these samples at room temperature. Strain varies both the sign and strength of the Fe-Cr superexchange coupling, resulting in a very interesting phase diagram for Bi2FeCrO6 thin films.

  13. A comparative investigation on structure and multiferroic properties of bismuth ferrite thin films by multielement co-doping

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Guohua; Tan, Guoqiang, E-mail: tan3114@163.com; Luo, Yangyang; Liu, Wenlong; Xia, Ao; Ren, Huijun

    2014-12-15

    Highlights: • Multielement (Tb, Cr and Mn) co-doped BiFeO{sub 3} films were fabricated by CSD method. • Multielement co-doping induces a structural transition. • It is found effective to stabilize the valence of Fe ions at +3 by the strategy. • The co-doping at A/B-sites gives rise to the superior multiferroic properties. - Abstract: (Tb, Cr and Mn) multielement co-doped BiFeO{sub 3} (BTFCMO) thin films were prepared by the chemical solution deposition method on fluorine doped tin oxide (FTO) substrates. X-ray diffraction, Rietveld refinement and Raman analyses revealed that a phase transition from rhombohedral to triclinic structure occurs in the multielement co-doped BiFeO{sub 3} films. It is found that the doping is conducive to stabilizing the valence of Fe ions and reducing leakage current. In addition, the highly enhanced ferroelectric properties with a huge remanent polarization (2P{sub r}) of 239.6 μC/cm{sup 2} and a low coercive field (2E{sub c}) of 615.6 kV/cm are ascribed to the well film texture, the structure transition and the reduced leakage current by the co-doping. Moreover, the structure transition is the dominant factor resulting in the significant enhancement observed in magnetization (M{sub s} ∼ 10.5 emu/cm{sup 3}), owing to the collapse of the space-modulated spin structure. In this contribution, these results demonstrate that the multielement co-doping is in favor of the enhanced multiferroic properties of the BFO films for possible multifunctional applications.

  14. Controlling magnetism with multiferroics

    Directory of Open Access Journals (Sweden)

    Ying-Hao Chu

    2007-10-01

    Full Text Available Multiferroics, materials combining multiple order parameters, offer an exciting way of coupling phenomena such as electronic and magnetic order. Using epitaxial growth and heteroepitaxy, researchers have grown high-quality thin films and heterostructures of the multiferroic BiFeO3. The ferroelectric and antiferromagnetic domain structure and coupling between these two order parameters in BiFeO3 is now being studied. We describe the evolution of our understanding of the connection between structure, properties, and new functionalities (including electrical control of magnetism using BiFeO3 as a model system.

  15. Local Magnetoelectric Effect in La-Doped BiFeO3 Multiferroic Thin Films Revealed by Magnetic-Field-Assisted Scanning Probe Microscopy.

    Science.gov (United States)

    Pan, Dan-Feng; Zhou, Ming-Xiu; Lu, Zeng-Xing; Zhang, Hao; Liu, Jun-Ming; Wang, Guang-Hou; Wan, Jian-Guo

    2016-12-01

    Multiferroic La-doped BiFeO3 thin films have been prepared by a sol-gel plus spin-coating process, and the local magnetoelectric coupling effect has been investigated by the magnetic-field-assisted scanning probe microscopy connected with a ferroelectric analyzer. The local ferroelectric polarization response to external magnetic fields is observed and a so-called optimized magnetic field of ~40 Oe is obtained, at which the ferroelectric polarization reaches the maximum. Moreover, we carry out the magnetic-field-dependent surface conductivity measurements and illustrate the origin of local magnetoresistance in the La-doped BiFeO3 thin films, which is closely related to the local ferroelectric polarization response to external magnetic fields. This work not only provides a useful technique to characterize the local magnetoelectric coupling for a wide range of multiferroic materials but also is significant for deeply understanding the local multiferroic behaviors in the BiFeO3-based systems. PMID:27356565

  16. Switching of both local ferroelectric and magnetic domains in multiferroic Bi0.9La0.1FeO3 thin film by mechanical force.

    Science.gov (United States)

    Jia, Tingting; Kimura, Hideo; Cheng, Zhenxiang; Zhao, Hongyang

    2016-01-01

    Cross-coupling of ordering parameters in multiferroic materials by multiple external stimuli other than electric field and magnetic field is highly desirable from both practical application and fundamental study points of view. Recently, mechanical force has attracted great attention in switching of ferroic ordering parameters via electro-elastic coupling in ferroelectric materials. In this work, mechanical force induced both polarization and magnetization switching were visualized in a polycrystalline multiferroic Bi0.9La0.1FeO3 thin film using a scanning probe microscopy system. The piezoresponse force microscopy and magnetic force microscopy responses suggest that both the ferroelectric domains and the magnetic domains in Bi0.9La0.1FeO3 film could be switched by mechanical force as well as by electric field. High tip stress applied on our thin film is demonstrated as able to induce ferroelastic switching and thus induce both ferroelectric dipole and magnetic spin flipping, as a consequence of electro-elastic coupling and magneto-electric coupling. The demonstration of mechanical force control of both the ferroelectric and the magnetic domains at room temperature provides a new freedom for manipulation of multiferroics and could result in devices with novel functionalities. PMID:27546488

  17. Electrical conduction mechanism and improved multiferroic properties of NFO/ (Pb0.50Sr0.50) TiO3 bilayer nanostructure composite thin film

    Science.gov (United States)

    Bala, Kanchan; Ram, Mast; Sharma, Hakikat; Negi, N. S.

    2016-05-01

    Multiferroic 2-2 type layered NFO/ (Pb0.50Sr0.50) TiO3 composite thin film on Pt/TiO2/Si substrate was prepared by novel metallo-Organic process using spin coating technique. The structural and surface morphology were confirmed by X-Ray diffraction (XRD) atomic force microscope (AFM). Significantly improved ferroelectric properties (Ps ˜ 8.69, Pr ˜ 3.19 µC/cm2 and Ec ˜ 419kV/cm) and magnetic properties (Ms), (Mr) and (Hc) is (104emu/cc, 0.8emu/cc and 25Oe.) were observed at room temperature. Our observation provides an effective way to manipulate the conduction behavior to understand the leakage current density of multiferroic composites film at the interface. Poole-Frankel tunneling conduction mechanism dominates the leakage current of films in the relatively high electric filed.

  18. Room-temperature magneto-dielectric response in multiferroic ZnFe2O4/PMN-PT bilayer thin films

    Science.gov (United States)

    Garg, T.; Kulkarni, A. R.; Venkataramani, N.

    2016-08-01

    The magneto-dielectric response in multiferroic ZnFe2O4/PMN-PT bilayer thin films prepared on a glass substrate using RF magnetron sputtering has been investigated in this work. PMN-PT thin films (i.e. PMN-PT/LCMO/Pt/Ti/glass) deposited on glass were used as a substrate for deposition of ZnFe2O4 thin films. ZnFe2O4 thin films were annealed ex situ at different temperatures. Structural, magnetic, ferroelectric, dielectric and magneto-dielectric studies were carried out on these multiferroic bilayer thin films. Structural studies revealed the presence of each layer in its respective single phase. Magnetic and ferroelectric studies revealed the ferromagnetic and ferroelectric behaviors of these bilayers. To quantify the magnetoelectric coupling, the dielectric constant of the bilayer was measured at room temperature as a function of frequency with and without the applied magnetic field. The magneto-dielectric response MD(%) was calculated by finding the relative change in dielectric constant at 1 kHz as a percentage. The observed MD response was correlated with magnetization of the ferrite layer. An MD response of 2.60% was found for a bilayer film annealed at 350 °C. At this particular annealing temperature, the ZnFe2O4 layer also has the highest saturation magnetization of 1900 G.

  19. Misfit strain driven cation inter-diffusion across an epitaxial multiferroic thin film interface

    Energy Technology Data Exchange (ETDEWEB)

    Sankara Rama Krishnan, P. S.; Munroe, Paul; Nagarajan, V. [School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales 2052 (Australia); Morozovska, Anna N.; Eliseev, Eugene A. [Institute of Physics, Institute of Material Sciences, NAS of Ukraine, 03028 Kiev (Ukraine); Ramasse, Quentin M.; Kepaptsoglou, Demie [SuperSTEM laboratory, SciTech Daresbury, Daresbury WA4 4AD (United Kingdom); Liang, Wen-I.; Chu, Ying-Hao [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China)

    2014-02-07

    Cation intermixing at functional oxide interfaces remains a highly controversial area directly relevant to interface-driven nanoelectronic device properties. Here, we systematically explore the cation intermixing in epitaxial (001) oriented multiferroic bismuth ferrite (BFO) grown on a (001) lanthanum aluminate (LAO) substrate. Aberration corrected dedicated scanning transmission electron microscopy and electron energy loss spectroscopy reveal that the interface is not chemically sharp, but with an intermixing of ∼2 nm. The driving force for this process is identified as misfit-driven elastic strain. Landau-Ginzburg-Devonshire-based phenomenological theory was combined with the Sheldon and Shenoy formula in order to understand the influence of boundary conditions and depolarizing fields arising from misfit strain between the LAO substrate and BFO film. The theory predicts the presence of a strong potential gradient at the interface, which decays on moving into the bulk of the film. This potential gradient is significant enough to drive the cation migration across the interface, thereby mitigating the misfit strain. Our results offer new insights on how chemical roughening at oxide interfaces can be effective in stabilizing the structural integrity of the interface without the need for misfit dislocations. These findings offer a general formalism for understanding cation intermixing at highly strained oxide interfaces that are used in nanoelectronic devices.

  20. Strain mediated coupling in magnetron sputtered multiferroic PZT/Ni-Mn-In/Si thin film heterostructure

    International Nuclear Information System (INIS)

    The strain mediated electrical and magnetic properties were investigated in PZT/Ni-Mn-In heterostructure deposited on Si (100) by dc/rf magnetron sputtering. X-ray diffraction pattern revealed that (220) orientation of Ni-Mn-In facilitate the (110) oriented tertragonal phase growth of PZT layer in PZT/Ni-Mn-In heterostructure. A distinctive peak in dielectric constant versus temperature plots around martensitic phase transformation temperature of Ni-Mn-In showed a strain mediated coupling between Ni-Mn-In and PZT layers. The ferroelectric measurement taken at different temperatures exhibits a well saturated and temperature dependent P-E loops with a highest value of Psat ∼ 55 μC/cm2 obtained during martensite-austenite transition temperature region of Ni-Mn-In. The stress induced by Ni-Mn-In layer on upper PZT film due to structural transformation from martensite to austenite resulted in temperature modulated Tunability of PZT/Ni-Mn-In heterostructure. A tunability of 42% was achieved at 290 K (structural transition region of Ni-Mn-In) in these heterostructures. I-V measurements taken at different temperatures indicated that ohmic conduction was the main conduction mechanism over a large electric field range in these heterostructures. Magnetic measurement revealed that heterostructure was ferromagnetic at room temperature with a saturation magnetization of ∼123 emu/cm3. Such multiferroic heterostructures exhibits promising applications in various microelectromechanical systems.

  1. Pr and Gd co-doped bismuth ferrite thin films with enhanced multiferroic properties

    Indian Academy of Sciences (India)

    Chang Chun Chen; Zi Xuan Liu; Gui Wang; Yi Lin Yan

    2014-12-01

    Pr and Gd co-modified Bi0.95−PrGd0.05FeO3 ( = 0.00, 0.05, 0.10) (BPGFO) thin films on Pt(111)/Ti/SiO2/Si(100) substrates were prepared by a sol-gel together with spin coating technique. A detailed study of electrical and magnetic properties of these thin films is reported. X-ray diffraction analysis shows that, with an increase in Pr content, the crystal structures of BPGFO thin films retain rhombohedral (R3c) symmetry accompanied by structure distortion. Polarization-electric field hysteresis loops of these thin films demonstrate that the incorporation of Pr and Gd into the Bi site of BiFeO3 thin film could enhance the ferroelectric performance. Compared to other thin films, the optimal ferroelectric behaviours in Bi0.85Pr0.1Gd0.05FeO3 thin film are ascribed to its large dielectric constant, low dissipation factor and low leakage current density. Room temperature magnetization-magnetic field curves of these thin films indicate that all the samples are of paramagnetic behaviours and the enhanced saturation magnetic properties can be found.

  2. Topological multiferroics

    Science.gov (United States)

    Scarrozza, Marco; Maccioni, Maria Barbara; Lopez, Giorgia M.; Fiorentini, Vincenzo

    2015-10-01

    Based on first-principles calculations, we explore an unconventional type of multiferroicity obtained via magnetic doping of wide-gap layered-perovskite ferroelectrics of the family A?Ti?O?. Using the ? member La?Ti?O? as home base, we substitute 3d atoms for Ti. The highlights of our results are that (1) low-concentration substitution of Ti by V produces robust unidirectional ferromagnetic (FM) order, resulting in a small-gap proper multiferroic, which in addition has electrically switchable magnetization, and (2) the isovalent substitution of Mn for Ti produces multiferroicity with weak FM order due to canting of antiferromagnetic Mn spins, and larger-than-usual linear magnetoelectric coupling.

  3. Influence of substrate and Ca substitution on multiferroic BiMnO3 thin films

    Indian Academy of Sciences (India)

    K S Pugazhvadivu; L Balakrishnan; K Tamilarasan

    2015-08-01

    BiMnO3 (BMO) and Ca (10 at%) substituted BiMnO3 (BCMO) thin films are grown on n-type Si (100) and Pt/Ti/SiO2/Si (100) substrates by RF magnetron sputtering. The structural, elemental, morphological, magnetic, dielectric and ferroelectric properties of the films are investigated by X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDAX), atomic force microscope (AFM), vibrating sample magnetometer (VSM), dielectric and ferroelectric measurements, respectively. The XRD pattern shows that the films acquire monoclinic structure with C2 space group. The elemental composition and surface roughness of the films are also measured by EDAX and AFM analysis, respectively. The VSM results exhibit that all the films possess room temperature ferromagnetism and the BCMO film deposited on the Si substrate has better magnetic properties (rem = 1.8 × 10−3 emu cm−3) than the other films. The dielectric measurement also reveals that the BCMO film has the highest value of dielectric constant (497) with less dielectric loss (0.3). Similarly, the ferroelectric measurement implies that all the films possess room temperature ferroelectricity.

  4. Grain size and stoichiometry control over RF-sputtered multiferroic BiFeO{sub 3} thin films on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Drera, Giovanni, E-mail: g.drera@dmf.unicatt.it; Giampietri, Alessio; Alessandri, Ivano; Magnano, Elena; Bondino, Federica; Nappini, Silvia

    2015-08-31

    This work reports the morphological and chemical characterization of multiferroic BiFeO{sub 3} polycrystalline thin films grown on Si(111) by RF-sputtering. Results are shown for a large set of samples and a wide array of experimental techniques, including imaging (atomic/piezoresponse force microscopy) and spectroscopic (μ-Raman, X-ray photoemission, X-ray diffraction) probes. Through growth and post-growth annealing treatment, a fine control over stoichiometry, grain size, grain orientation, crystal order and surface roughness is achieved. In particular, the grain size can be tailored from nanocrystals to large micrometric plates as a function of the annealing temperature. For the optimal stoichiometric sample, an additional X-ray absorption and magnetic circular dichroism analysis has been carried out, which provides high quality spectra comparable with epitaxial films and further proves the expected strong local antiferromagnetic order. - Highlights: • We show the growth of polycristalline multiferroic BiFeO{sub 3} on Si(111) by RF-sputtering. • Multi-technique (AFM/PFM,XPS,XRD,XAS,XMCD,Raman) characterization is given. • Crystal size, homogeneity and chemistry are tailored by growth or post-growth annealing. • In optimal conditions, piezoelectricity, ferroelectricity and magnetism are found.

  5. Room-temperature multiferroic properties of Pb(Zr0.57Ti0.43)O3-Pb(Fe0.67W0.33)O3 solid-solution epitaxial thin films

    International Nuclear Information System (INIS)

    We report on the multiferroic properties of single-phase (PbZr0.57Ti0.43O3)0.8(PbFe0.67W0.33 O3)0.2 solid-solution (PZT-PFW) epitaxial thin films. The epitaxial PZT-PFW thin films are deposited using a pulsed laser deposition method. An optimized growth condition has been indentified to achieve single-phase epitaxial thin films. Our films clearly show ferroelectric and weak ferromagnetic properties at room temperature. The synthesis of single-phase solid-solution materials using conventional ferroelectrics and relaxor ferroelectrics might open a way to realize a room-temperature multiferroic material.

  6. Room temperature magnetoelectric coupling in BaTi{sub 1−x}Cr{sub x}O{sub 3} multiferroic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sundararaj, Anuraj; Chandrasekaran, Gopalakrishnan, E-mail: hod.nano@ktr.srmuniv.ac.in; Therese, Helen Annal [Nanotechnology Research Center, SRM University, Kattankulathur 603203, Tamilnadu (India); Annamalai, Karthigeyan [Department of Physics and Nanotechnology, SRM University, Kattankulathur 603203, Tamilnadu (India)

    2016-01-14

    We report on room temperature (RT) magnetoelectric coupling in tetragonal BaTi{sub 1−x}Cr{sub x}O{sub 3} thin film multiferroics (BTCO) sputter deposited on (100) SrTiO{sub 3} (where x = 0.005, 0.01, 0.02, and 0.03). As-deposited thin films are vacuum annealed by electron beam rapid thermal annealing technique. 50 nm thick BTCO with “x = 0.01” shows RT ferromagnetic and ferroelectric response with saturation magnetic moment of 1120 emu/cc and polarization of 14.7 microcoulomb/cm{sup 2}. Piezoresponse/magnetic force microscope images shows RT magnetoelectric coupling in BTCO with “x = 0.01,” which is confirmed using magnetocapacitance measurement where an increase in capacitance from 17.5 pF to 18.4 pF is observed with an applied magnetic field.

  7. Correlation of High Magnetoelectric Coupling with Oxygen Vacancy Superstructure in Epitaxial Multiferroic BaTiO3-BiFeO3 Composite Thin Films

    Directory of Open Access Journals (Sweden)

    Michael Lorenz

    2016-01-01

    Full Text Available Epitaxial multiferroic BaTiO3-BiFeO3 composite thin films exhibit a correlation between the magnetoelectric (ME voltage coefficient αME and the oxygen partial pressure during growth. The ME coefficient αME reaches high values up to 43 V/(cm·Oe at 300 K and at 0.25 mbar oxygen growth pressure. The temperature dependence of αME of the composite films is opposite that of recently-reported BaTiO3-BiFeO3 superlattices, indicating that strain-mediated ME coupling alone cannot explain its origin. Probably, charge-mediated ME coupling may play a role in the composite films. Furthermore, the chemically-homogeneous composite films show an oxygen vacancy superstructure, which arises from vacancy ordering on the {111} planes of the pseudocubic BaTiO3-type structure. This work contributes to the understanding of magnetoelectric coupling as a complex and sensitive interplay of chemical, structural and geometrical issues of the BaTiO3-BiFeO3 composite system and, thus, paves the way to practical exploitation of magnetoelectric composites.

  8. All-thin-film PZT/FeGa Multiferroic Cantilevers and Their Applications in Switching Devices and Parametric Amplification

    Science.gov (United States)

    Wang, Yi; Onuta, Tiberiu-Dan; Long, Chris; Lofland, Samuel; Takeuchi, Ichiro

    2014-03-01

    We are investigating the characteristics of microfabricated PZT/FeGa multiferroic cantilevers. The cantilevers can be driven by AC or DC magnetic and electric field, and the device response can be read off as a piezo-induced voltage. We can use the multiple input parameters to operate the devices in a variety of manners for different applications. They include electromagnetic energy harvesting, pulse triggered nonlinear memory devices, and parametrically amplified ME sensors. Due to the competition of anisotropy and Zeeman energies, the mechanical resonant frequency of the cantilevers was found to follow a hysteresis behavior with DC bias magnetic field applied in the cantilever easy axis. We can also control and tune the occurrence of nonlinear bifurcation in the frequency spectrum. The resulting hysteresis in the frequency spectrum can be used to make switching devices, where the input can be DC electric and magnetic fields, as well as pulses of AC fields. We have also demonstrated parametric pumping of the response from an AC magnetic field using frequency-doubled AC electric field. The enhanced equivalent ME coefficient is as high as 10 million V/(cm*Oe), when the pumping voltage is very close to a threshold voltage. The quality factor also increases from 2000 to 80000 with pumping.

  9. Epitaxial growth of multiferroic Pb(Zr0.57Ti0.43)O3-Pb(Fe2/3W1/3)O3 solid-solution thin films and their magnetoelectric effects

    OpenAIRE

    Lee, D.; Park, Y. -A.; S. M. Yang; Song, T. K.; Jo, Y; Hur, N.; Jung, J H; Noh, T. W.

    2010-01-01

    We report on epitaxial growth of single-phase [Pb(Zr0.57Ti0.43)O3]0.8[Pb(Fe2/3W1/3)O3]0.2 (PZT-PFW) solid-solution thin films using pulsed laser deposition. X-ray diffraction measurements reveal that the films have a tetragonal structure. The films exhibit ferroelectric properties and weak ferromagnetic responses at room temperature. Magnetoelectric effects were investigated; the nonlinear magnetoelectric coefficient was measured and found to be comparable to those of multiferroic hexagonal m...

  10. Enhancement of multiferroic properties of Pb(Fe1/2Nb1/2)O-3 thin films on SrRuO3 buffered SrTiO3 substrates

    OpenAIRE

    Yan, Li; Zhao, X.; Li, Jiefang; Viehland, Dwight D.

    2009-01-01

    We report multiferroic properties of Pb(Fe1/2Nb1/2)O-3 (or PFN) epitaxial thin layers grown on (001), (110), and (111) SrTiO3 substrates with and without a SrRuO3 (SRO) buffer. Our findings are as follows: (i) the constraint stress on (001) substrates is more than ten times larger than those on (110) and (111); (ii) this large constraint stress induces higher piezoelectric constants, magnetic permeability and magnetization for (001) PFN compared with (110) and (111) layers; (iii) epitaxy dist...

  11. Low energy consumption spintronics using multiferroic heterostructures

    International Nuclear Information System (INIS)

    We review the recent progress in the field of multiferroic magnetoelectric heterostructures. The lack of single phase multiferroic candidates exhibiting simultaneously strong and coupled magnetic and ferroelectric orders led to an increased effort into the development of artificial multiferroic heterostructures in which these orders are combined by assembling different materials. The magnetoelectric coupling emerging from the created interface between the ferroelectric and ferromagnetic layers can result in electrically tunable magnetic transition temperature, magnetic anisotropy or magnetization reversal. The full potential of low energy consumption magnetic based devices for spintronics lies in our understanding of the magnetoelectric coupling at the scale of the ferroic domains. Although the thin film synthesis progresses resulted into the complete control of ferroic domain ordering using epitaxial strain, the local observation of magnetoelectric coupling remains challenging. The ability to imprint ferroelectric domains into ferromagnets and to manipulate those solely using electric fields suggests new technological advances for spintronics such as magnetoelectric memories or memristors. (topical review)

  12. Growth, structure, surface topography and magnetic properties of GdMnO3 multiferroic epitaxial thin films

    Directory of Open Access Journals (Sweden)

    Mukovskii Ya.

    2013-01-01

    Full Text Available Epitaxial GdMnO3 thin films were grown in various regimes on (001 NdGaO3 and (001 SrTiO3 substrates by RF magnetron sputtering. X-ray analysis revealed that the films grown at a substrate temperature of 650-900 °C are single phase (GdMnO3 with orthorhombic Pbnm structure. Films grown on NdGaO3 substrates at lower temperature (750 °C reveal two orientations, i.e. GdMnO3(001||NdGaO3(001 and GdMnO3(110||NdGaO3(001. These results are confirmed by transmission electron microscopy. Films grown on SrTiO3 substrates have two orientations, i.e. GdMnO3(001||SrTiO3(001 and GdMnO3(110||SrTiO3(001, in the whole temperature range in which the phase exists. Using atomic force microscopy the correlation between the topography of the films and their crystallographic structure was studied. The magnetic properties of the films differ from those of bulk samples and revealed spin-glass behavior.

  13. Phase transitions and domain structures in multiferroics

    Science.gov (United States)

    Vlahos, Eftihia

    2011-12-01

    Thin film ferroelectrics and multiferroics are two important classes of materials interesting both from a scientific and a technological prospective. The volatility of lead and bismuth as well as environmental issues regarding the toxicity of lead are two disadvantages of the most commonly used ferroelectric random access memory (FeRAM) materials such as Pb(Zr,Ti)O3 and SrBi2Ta2O9. Therefore lead-free thin film ferroelectrics are promising substitutes as long as (a) they can be grown on technologically important substrates such as silicon, and (b) their T c and Pr become comparable to that of well established ferroelectrics. On the other hand, the development of functional room temperature ferroelectric ferromagnetic multiferroics could lead to very interesting phenomena such as control of magnetism with electric fields and control of electrical polarization with magnetic fields. This thesis focuses on the understanding of material structure-property relations using nonlinear optical spectroscopy. Nonlinear spectroscopy is an excellent tool for probing the onset of ferroelectricity, and domain dynamics in strained ferroelectrics and multiferroics. Second harmonic generation was used to detect ferroelectricity and the antiferrodistortive phase transition in thin film SrTiO3. Incipient ferroelectric CaTiO3 has been shown to become ferroelectric when strained with a combination of SHG and dielectric measurements. The tensorial nature of the induced nonlinear polarization allows for probing of the BaTiO3 and SrTiO3 polarization contributions in nanoscale BaTiO3/SrTiO3 superlattices. In addition, nonlinear optics was used to demonstrate ferroelectricity in multiferroic EuTiO3. Finally, confocal SHG and Raman microscopy were utilized to visualize polar domains in incipient ferroelectric and ferroelastic CaTiO3.

  14. Multiferroic Compounds with Double-Perovskite Structures

    Directory of Open Access Journals (Sweden)

    Noriya Ichikawa

    2011-01-01

    Full Text Available New multiferroic compounds with double-perovskite structures were synthesized. Bi2NiMnO6 was synthesized in bulk form by high-pressure synthesis and also in a thin-film form by epitaxial growth. The material showed both ferromagnetic and ferroelectric properties, i.e., the multiferroic property at low temperature. Bi2FeCrO6 was also fabricated in a (1 1 1 oriented BiFeO3/BiCrO3 artificial superlattice, with a 1/1 stacking period. The superlattice film showed ferromagnetic behavior and polarization switching at room temperature. In the compounds, Bi3+ ion, located at the A site in the perovskite structure, caused ferroelectric structural distortion, and the B-site ordering of the Ni2+ and Mn4+ ions (Fe3+ and Cr3+ ions in a rock-salt configuration led to ferromagnetism according to the Kanamori-Goodenough rule.

  15. Effect of annealing temperature on multiferroic properties of Bi0.85Nd0.15FeO3 thin films prepared by sol-gel method

    Institute of Scientific and Technical Information of China (English)

    GOTO; Takashi

    2010-01-01

    Bi0.85Nd0.15FeO3 films were prepared on Pt/Ti/SiO2/Si substrate by a sol-gel method,and annealed at different temperatures.The effect of annealing temperature on the crystal structure,dielectric,ferroelectric,and ferromagnetic properties was investigated.When the Bi0.85Nd0.15FeO3 films were annealed at 490-600°C,the single phase was obtained.Bi0.85Nd0.15FeO3 film annealed at 600°C showed good multiferroic properties with εr of 145 (at 1 MHz),Ms of 44.8 emu/cm3,and 2Pr of 16.6 μC/cm2.

  16. Engineering charge ordering into multiferroicity

    OpenAIRE

    He, Xu; Jin, Kui-juan

    2016-01-01

    Multiferroic materials have attracted great interests but are rare in nature. In many transitional metal oxides, charge ordering and magnetic ordering coexist, so that a method of engineering charge-ordered materials into ferroelectric materials would lead to a large class of multiferroic materials. We propose a strategy for designing new ferroelectric or even multiferroic materials by inserting a spacing layer into each two layers of charge-ordered materials and artificially making a superla...

  17. CoFe2/Al2O3/PMNPT multiferroic heterostructures by atomic layer deposition

    Science.gov (United States)

    Zhou, Ziyao; Grocke, Garrett; Yanguas-Gil, Angel; Wang, Xinjun; Gao, Yuan; Sun, Nianxiang; Howe, Brandon; Chen, Xing

    2016-05-01

    Multiferroic materials and applications allow electric bias control of magnetism or magnetic bias control of polarization, enabling fast, compact, energy-efficient devices in RF/microwave communication systems such as filters, shifters, and antennas; electronics devices such as inductors and capacitors; and other magnetic material related applications including sensors and memories. In this manuscript, we utilize atomic layer deposition technology to grow magnetic CoFe metallic thin films onto PMNPT, with a ˜110 Oe electric field induced ferromagnetic resonance field shift in the CoFe/Al2O3/PMNPT multiferroic heterostructure. Our work demonstrates an atomic layer deposition fabricated multiferroic heterostructure with significant tunability and shows that the unique thin film growth mechanism will benefit integrated multiferroic application in near future.

  18. Structural, electrical, and magnetic properties of multiferroic Bi1-xGdxFe0.97Co0.03O3 thin films

    International Nuclear Information System (INIS)

    Highlights: • The BGFC exhibit a series of structural phase transitions at room temperature. • The remanent magnetizations of the BGFC are determined by the Fe2+ concentration. • Gd composition driven ferroelectric to antiferroelectric phase transition in BGFC. • Well established ferroelectric property is observed in BGFC (x = 0.12). - Abstract: Single-phase Bi1-xGdxFe0.97Co0.03O3 (BGFC, x = 0.04-0.16) thin films were successfully synthesized by using a chemical solution deposition method. The BGFC thin films exhibit a series of structural phase transitions as a function of Gd composition, accompanied by dramatic changes in the ferroelectric, leakage current and dielectric properties. It has been demonstrated that Gd doping at Bi-site can monotonously decrease the remanent magnetization, mainly due to the gradual decrease in Fe2+ content. Weak compress stress favors the ferromagnetism in the BGFC (x = 0.08) thin film, which takes a maximum saturation magnetization of 13.2 emu/cm3 with the smallest coercivity of 120 Oe. At particular composition of x = 0.12, the film exhibits rectangular hysteresis loop and sharp polarization current curve, a giant remanent polarization of 101 μC/cm2 and a small coercive field of 345 kV/cm is observed. This paper reports that rare earth driven ferroelectric to antiferroelectric (AFE) phase transition can be obtained at room temperature in the binary elements codoped BFO thin films. Besides, the defect polarization serves approximatively as the AFE domains blocking the ferroelectric switching

  19. Coupling Magnetism to Electricity in Multiferroic Heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ramesh, R [U.S. DOE

    2012-02-15

    Complex perovskite oxides exhibit a rich spectrum of functional responses, including magnetism, ferroelectricity, highly correlated electron behavior, superconductivity, etc. The basic materials physics of such materials provide the ideal playground for interdisciplinary scientific exploration. Over the past decade we have been exploring the science of such materials (for example, colossal magnetoresistance, ferroelectricity, etc) in thin-film form by creating epitaxial heterostructures and nanostructures. Among the large number of materials systems, there exists a small set of materials which exhibit multiple order parameters; these are known as multiferroics. Using our work in the field of ferroelectric and ferromagnetic oxides as the background, we are now exploring such materials as epitaxial thin films, as well as nanostructures. Specifically, we are studying the role of thin-film growth, heteroepitaxy, and processing on the basic properties as well as the magnitude of the coupling between the order parameters. In our work we are exploring the switchability of the antiferromagnetic order using this coupling. What is the importance of this work? Antiferromagnets are pervasive in the recording industry. They are used as exchange biasing layers in magnetic tunnel junctions, etc. However, to date there has been no antiferomagnet that is electrically tunable. We believe that the multiferroic BiFeO3 is one compound where this can be observed at room temperature. The next step is to explore the coupling of a ferromagnet to this antiferromagnet through the exchange biasing concept. Ultimately, this will give us the opportunity to switch the magnetic state in a ferromagnet (and therefore the spin polarization direction) by simply applying an electric field to the underlying antiferromagnetic ferroelectric. In this talk, I will describe our progress to date on this exciting possibility.

  20. Multiferroic epitaxial Pb(Fe1/2Nb1/2)O-3 thin films: A relaxor ferroelectric/weak ferromagnet with a variable structure

    OpenAIRE

    Yan, Li; Li, Jiefang; Suchicital, C.; Viehland, Dwight D.

    2006-01-01

    The authors report the structural, ferroelectric, and ferromagnetic properties of Pb(Fe1/2Nb1/2)O-3 epitaxial thin layers grown on (001), (110), and (111) SrTiO3 substrates by pulsed-laser deposition; films were of sufficient resistivity to enable high-field P-E measurements. Findings are as follows: epitaxial strain results in (i) a dramatic increase in the spontaneous polarization P-s; (ii) a lattice structure that is dependent on substrate orientation; (iii) a slim-loop P-E response and re...

  1. Engineering charge ordering into multiferroicity

    Science.gov (United States)

    He, Xu; Jin, Kui-juan

    2016-04-01

    Multiferroic materials have attracted great interest but are rare in nature. In many transition-metal oxides, charge ordering and magnetic ordering coexist, so that a method of engineering charge-ordered materials into ferroelectric materials would lead to a large class of multiferroic materials. We propose a strategy for designing new ferroelectric or even multiferroic materials by inserting a spacing layer into each two layers of charge-ordered materials and artificially making a superlattice. One example of the model demonstrated here is the perovskite (LaFeO3)2/LaTiO3 (111) superlattice, in which the LaTiO3 layer acts as the donor and the spacing layer, and the LaFeO3 layer is half doped and performs charge ordering. The collaboration of the charge ordering and the spacing layer breaks the space inversion symmetry, resulting in a large ferroelectric polarization. As the charge ordering also leads to a ferrimagnetic structure, (LaFeO3)2/LaTiO3 is multiferroic. It is expected that this work can encourage the designing and experimental implementation of a large class of multiferroic structures with novel properties.

  2. Intrinsic defect-mediated conduction and resistive switching in multiferroic BiFeO3 thin films epitaxially grown on SrRuO3 bottom electrodes

    Science.gov (United States)

    Lee, Ji Hye; Jeon, Ji Hoon; Yoon, Chansoo; Lee, Sangik; Kim, Yeon Soo; Oh, Tae Joon; Kim, Young Heon; Park, Jinsu; Song, Tae Kwon; Park, Bae Ho

    2016-03-01

    We report the impact of intrinsic defects in epitaxial BiFeO3 films on charge conduction and resistive switching of Pt/BiFeO3/SrRuO3 capacitors, although the BiFeO3 films show very similar ferroelectric domain types probed by piezoresponse force microscopy. Capacitors with p-type Bi-deficient and n-type Bi-rich BiFeO3 films exhibit switchable diode and conventional bipolar resistive switching behaviors, respectively. Both the capacitors show good retention properties with a high ON/OFF ratio of >100 in Bi-deficient films and that of >1000 in Bi-rich films. The present investigation advances considerably understanding of interface control through defect engineering of BiFeO3 thin films for non-volatile memory application.

  3. Multiferroic properties and magnetoelectric coupling in highly textured Pb(Fe0.5Nb0.5)O3 thin films obtained by RF sputtering

    International Nuclear Information System (INIS)

    The ferroelectric and magnetic properties and the magnetoelectric coupling (MEC) effects of Pb(Fe0.5Nb0.5)O3 (PFN) thin films grown on SrRuO3/Si substrates by the radiofrequency (RF) magnetron sputtering technique were studied. Highly textured, single-phase films with [1 1 0] preferential orientation and different thicknesses were successfully grown. Electric (P–E) hysteresis loops showed excellent and almost constant values of the maximum (∼65 μC cm−2) and remanent (∼25 μC cm−2) polarizations from 4 K to room temperature. Ferromagnetic order in the low-temperature region (below 50 K) is reported for the first time in PFN and discussed. The maximum (∼3 emu g−1) and remanent (∼1.5 emu g−1) magnetization values were obtained. Magnetic field dependence of the ferroelectric hysteresis loops was investigated for temperatures of between 4 and 100 K. Coexistence of ferroelectricity, magnetism and spin crossover phenomena were observed, and a significant direct DC MEC effect expressed by the coefficient α = ΔPr/ΔH with maximum value of 120 pC cm−2 Oe−1 at 4 K is reported

  4. Spintronics with multiferroics

    International Nuclear Information System (INIS)

    In this paper, we review the recent research on the functionalization of multiferroics for spintronics applications. We focus more particularly on antiferromagnetic and ferroelectric BiFeO3 and its integration in several types of architectures. For instance, when used as a tunnel barrier, BiFeO3 allows the observation of a large tunnel magnetoresistance with Co and (La,Sr)MnO3 ferromagnetic electrodes. Also, its antiferromagnetic and magnetoelectric properties have been exploited to induce an exchange coupling with a ferromagnet. The mechanisms of such an exchange coupling open ways to electrically control magnetization and possibly the logic state of spintronics devices. We also discuss recent results concerning the use of ferromagnetic and ferroelectric (La,Bi)MnO3 as an active tunnel barrier in magnetic tunnel junctions with Au and (La,Sr)MnO3 electrodes. A four-resistance-state device has been obtained, with two states arising from a spin filtering effect due to the ferromagnetic character of the barrier and two resulting from the ferroelectric behavior of the (La,Bi)MnO3 ultrathin film. These results show that the additional degree of freedom provided by the ferroelectric polarization brings novel functionalities to spintronics, either as a extra order parameter for multiple-state memory elements, or as a handle for gate-controlled magnetic memories.

  5. Epitaxial growth and multiferroic properties of cation-engineered (Bi{sub 0.45}La{sub 0.05}Ba{sub 0.5})(Fe{sub 0.75}Nb{sub 0.25})O{sub 3} thin film on Ir-buffered (0 0 1) MgO substrate

    Energy Technology Data Exchange (ETDEWEB)

    Paik, Hanjong [Department of Materials Science and Engineering, Cornell University, Ithaca NY 14853 (United States); Kim, Hyun-Suk [Department of Materials Engineering, Chungnam University, Daejeon 305-764 (Korea, Republic of); Hong, Jongin, E-mail: hongj@cau.ac.kr [Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 156-756 (Korea, Republic of)

    2015-04-15

    Highlights: • Epitaxial (Bi{sub 0.45}La{sub 0.05}Ba{sub 0.5})(Fe{sub 0.75}Nb{sub 0.25})O{sub 3} thin film was grown on the Ir-buffered (0 0 1) MgO substrate by pulsed laser deposition. • Its ferroelectric polarization switching was investigated by piezoresponse force microscopy. • Its ferromagnetic hysteresis at room temperature and ferrimagnetic–ferromagnetic transition at low temperature were evaluated. • Artificial A- and B-site cation engineering would result in stable multiferroic properties at room temperature. - Abstract: An epitaxial (Bi{sub 0.45}La{sub 0.05}Ba{sub 0.5})(Fe{sub 0.75}Nb{sub 0.25})O{sub 3} (BLB-FNO) thin film was successfully grown on an Ir-buffered (0 0 1) MgO substrate by pulsed laser deposition (PLD). The “cube-on-cube” epitaxial relation, (0 0 1)[1 0 0] BLB-FNO//(0 0 1)[1 0 0] Ir//(0 0 1)[1 0 0] MgO, was confirmed by X-ray diffraction (XRD) pole figures and cross-sectional high-resolution transmission electron microscopy (HRTEM). The ferroelectric polarization switching of the BLB-FNO thin film was investigated by piezoresponse force microscopy (PFM). Its magnetic properties, such as ferromagnetic hysteresis at room temperature and possible magnetic transition at low temperature, were also evaluated. Accordingly, we successfully demonstrated that artificial A- and B-site cation engineering would allow for stable multiferroic properties at room temperature.

  6. Quantitative investigation of magnetoelectric coupling in various forms of multiferroics

    Science.gov (United States)

    Kim, Kee Hoon

    2009-03-01

    Magnetoelectric susceptibility (MES) is probably the most direct way of estimating the magnitude of magnetoelectric coupling in many forms of magnetoelectric and/or multiferroic materials. Historically, the MES has been measured in numerous existing magnetoelectric materials in broad field, frequency, and temperature ranges and their MES values have been tabulated [1]. With growing interest worldwide toward applications of multiferroics for novel memory and sensor devices, however, there have been ever-increasing demands to measure quantitatively the MES of multiferroic thin films. Yet, the measurements of thin film MES become challenging in spite of its large MES value because the magnetoelectric voltages, proportional to the film thickness, usually get too small to be measured reliably. Herein, we introduce a highly sensitive magnetoelectric susceptometer that can detect the charge variation down to ˜10-17C in a few gauss oscillating magnetic field. Using this specific setup, we could measure the MES of multiferroic thin films or single crystals with unprecedented accuracy and sensitivity in cryogenic (down to 2 K) and magnetic field (up to 9 T) environments. In this talk, we summarize a number of key results based on this technique; (1) MES of a 300 nm BiFeO3-CoFe2O4 nanopillar structure as well as those of a 250 nm BiFeO3 film and of a BiFeO3 single crystal. (2) MES of (Pb,Zr)TiO3-NiFe2O4 nanocomposite films, and (3) temperature- and field-dependent MES in representative multiferroic crystals/films including TbMn2O5 , GaFeO3, and Cr2O3. In particular, we demonstrate that the MES of the film with the nanopillar structure is enhanced by approximately one order of magnitude reaching 2×10-10 s/m at room temperature, compared with those of a pure BiFeO3 film and a single crystal. Furthermore, based on detailed field and temperature dependent MES studies, we show that magnetoelectric coupling in TbMn2O5 has been mediated and amplified by the large magnetoelastic

  7. Multiferroic materials tower up

    International Nuclear Information System (INIS)

    For generations humans have been engineering pillars that have more than one function. The giant stone pillars of the 9th-century Cordoba Mosque in Andalusia, Spain, for example, provide both structural stability and aesthetic appeal. Now researchers in the US have built pillar structures at the nanometre scale that combine two markedly different functions: magnetism and ferroelectricity. The technological importance of these 21st century nanopillars could be as far reaching as that of the ancient building techniques used in Andalusia. Magnetic materials are ubiquitous, from the huge transformer cores in electrical power sub-stations to the tiny magnetic particles that are used to store data on our computer disks. The widespread applications of magnets stem from two basic properties. First, they have a spontaneous magnetic moment, which enables magnetic flux to be concentrated in transformers. Second, the orientation of the magnetism can be switched back and forth by an applied magnetic field, and can therefore be used for data storage. Similarly, ferroelectric materials have a spontaneous electric polarization, the direction of which can be switched with an applied electric field. In fact, the 'ferro' part of the name arises because their electrical properties are similar to the magnetic properties of iron-based magnetic materials; most, however, are not ferrous in the sense that they contain iron. Ferroelectrics are used to make capacitors with high dielectric constants, and also have applications in nonvolatile data storage and sonar. Now, Haimei Zheng of the University of Maryland and colleagues in the US have adopted a different approach, which I believe is much more promising for producing useful magneto-electric multiferroics. Instead of trying to produce a single compound, they grow a closely interwoven composite material from magnetic cobalt ferrite (CoFe2O4) and ferroelectric barium titanate (BaTiO3). To do this, the team used a well established growth

  8. Functional domain walls in multiferroics

    Science.gov (United States)

    Meier, Dennis

    2015-11-01

    During the last decade a wide variety of novel and fascinating correlation phenomena has been discovered at domain walls in multiferroic bulk systems, ranging from unusual electronic conductance to inseparably entangled spin and charge degrees of freedom. The domain walls represent quasi-2D functional objects that can be induced, positioned, and erased on demand, bearing considerable technological potential for future nanoelectronics. Most of the challenges that remain to be solved before turning related device paradigms into reality, however, still fall in the field of fundamental condensed matter physics and materials science. In this topical review seminal experimental findings gained on electric and magnetic domain walls in multiferroic bulk materials are addressed. A special focus is put on the physical properties that emerge at so-called charged domain walls and the added functionality that arises from coexisting magnetic order. The research presented in this review highlights that we are just entering a whole new world of intriguing nanoscale physics that is yet to be explored in all its details. The goal is to draw attention to the persistent challenges and identify future key directions for the research on functional domain walls in multiferroics.

  9. Multiferroic properties in terbium orthoferrite

    International Nuclear Information System (INIS)

    Multiferroic properties in a polycrystalline terbium orthoferrite are investigated. Different thermomagnetic behaviors are observed in different magnetic fields, which is attributed to the suppression of the low temperature magnetic phase by an external magnetic field. Further studies reveal that the ferroelectricity originates from the spin configuration below 3.5 K. In addition, the magnetic field control of electric polarization and dielectric constant is observed, which suggests a magnetoelectric effect in TbFeO3. The origin of ferroelectricity in this rare-earth orthoferrite is discussed. (rapid communication)

  10. Multiferroicity in Perovskite Manganite Superlattice

    Science.gov (United States)

    Tao, Yong-Mei; Jiang, Xue-Fan; Liu, Jun-Ming

    2016-08-01

    Multiferroic properties of short period perovskite type manganite superlattice ((R1MnO3)n/(R2MnO3)n (n=1,2,3)) are considered within the framework of classical Heisenberg model using Monte Carlo simulation. Our result revealed the interesting behaviors in Mn spins structure in superlattice. Apart from simple plane spin cycloid structure which is shown in all manganites including bulk, film, and superlattice here in low temperature, a non-coplanar spiral spin structure is exhibited in a certain temperature range when n equals 1, 2 or 3. Specific heat, spin-helicity vector, spin correlation function, spin-helicity correlation function, and spin configuration are calculated to confirm this non-coplanar spiral spin structure. These results are associated with the competition among exchange interaction, magnetic anisotropy, and Dzyaloshinskii-Moriya interaction. Supported by the National Natural Science Foundation of China (NSFC) under Grant No. 11447136

  11. Bismuth centred magnetic perovskite: A projected multiferroic

    International Nuclear Information System (INIS)

    In recent time substantial attention has been initiated to understand the physics behind multiferroism and to design new multiferroic materials. BiMnO3 and BiFeO3 are the well-studied Bi-centred multiferroic oxides. BiMnO3 is a ferromagnetic–ferroelectric (metastable) phase and require drastic conditions to synthesize. However, lanthanum substituted BiMnO3 phases stabilized at ambient pressure. It is thus of major importance to increase the number of ferromagnetic perovskites with Bi cations that could be designed under ambient conditions. In this article, we have presented an up to date report of investigations on Bi-centred magnetic perovskites, a prospective material for multiferroic application. Central focus is concentrated on La0.5Bi0.5MnO3 perovskite with various substitutions at different levels. A few of these perovskites are found to be of practical importance e.g. La0.5Bi0.5Mn0.67Co0.33O3 with high dielectric permittivity coupled with ferromagnetism. A comprehensive analysis of different physical functionalities and their interrelation for a wide range of compositions of these Bi-centred perovskites is presented. It has been found that the complex magnetic behaviour originates from mixed valence metal ions. The ferroelectricity is associated with the 6s2 lone pair of Bi3+ cations. The magnetic ground state influences the dielectric properties reflecting the multiferroism in a single material. - Highlights: • Multiferroics have attracted increasing attention due to their possible device applications. • Bismuth centred magnetic perovskite is one kind of such promising multiferroic materials. • Ferromagnetic Bi-perovskites, which are synthesized at ambient conditions, have been discussed

  12. Magnetoelectric imaging of multiferroic heterostructures (Presentation Recording)

    Science.gov (United States)

    Ghidini, Massimo; Lesaine, Arnaud; Zhu, Bonan; Moya, Xavier; Yan, Wenjing; Crossley, Sam; Nair, Bhasi; Mansell, Rhodri; Cowburn, Russell P.; Barnes, Crispin H. W.; Kronast, Florian; Valencia, Sergio; Maccherozzi, Francesco; Dhesi, Sarnjeet S.; Mathur, Neil

    2015-09-01

    Electrical control of magnetism has been demonstrated in multiferroic compounds and ferromagnetic semiconductors, but electrical switching of a substantial net magnetization at room temperature has not been demonstrated in these materials. This goal has instead been achieved in heterostructures comprising ferromagnetic films in which electrically driven magnetic changes arise due to strain or exchange bias from ferroic substrates, or due to charge effects induced by a gate. However, previous work focused on electrical switching of an in-plane magnetization or involved the assistance of applied magnetic fields. In heterostructures made of juxtaposed ferroelectric and ferromagnetic layers, we have shown electrical control with no applied magnetic field of the perpendicular magnetization of small features [1] and of magnetic stripe domains patterns [2]. Here we investigate Ni81Fe19 films on ferroelectric substrates with and without buffer layers of Cu, whose presence precludes charge-mediated coupling. Ni81Fe19 has virtually zero magnetostriction, but sufficiently thin films show large magnetostriction, and thus, on increasing film thickness through the threshold for zero magnetostriction, we have seeked the crossover from charge- to strain-mediated coupling. We will then show that strain associated with the motion of 90°- ferroelectric domain walls in a BaTiO3 substrate, can switch the magnetization of an array of overlying single-domain Ni dots. [1] M. Ghidini, R. Pellicelli, J. L. Prieto, X. Moya, J. Soussi, J. Briscoe, S. Dunn and N. D. Mathur, Nature Communications 4 (2013) 1453. [2] M. Ghidini, F.Maccherozzi, X. Moya, L. C. Phillips, W.Yan, J. Soussi, N. Métallier, M.Vickers, , N. -J.Steinke, R. Mansell, C. H. W. Barnes, S. S. Dhesi, and N. D. Mathur, Adv. Mater.doi: 10.1002/adma.201404799 (2015).

  13. Multiferroic crossover in perovskite oxides

    Science.gov (United States)

    Weston, L.; Cui, X. Y.; Ringer, S. P.; Stampfl, C.

    2016-04-01

    The coexistence of ferroelectricity and magnetism in A B O3 perovskite oxides is rare, a phenomenon that has become known as the ferroelectric "d0 rule." Recently, the perovskite BiCoO3 has been shown experimentally to be isostructural with PbTiO3, while simultaneously the d6Co3 + ion has a high-spin ground state with C -type antiferromagnetic ordering. It has been suggested that the hybridization of Bi 6 s states with the O 2 p valence band stabilizes the polar phase, however, we have recently demonstrated that Co3 + ions in the perovskite structure can facilitate a ferroelectric distortion via the Co 3 d -O 2 p covalent interaction [L. Weston, et al., Phys. Rev. Lett. 114, 247601 (2015), 10.1103/PhysRevLett.114.247601]. In this paper, using accurate hybrid density functional calculations, we investigate the atomic, electronic, and magnetic structure of BiCoO3 to elucidate the origin of the multiferroic state. To begin with, we perform a more general first-principles investigation of the role of d electrons in affecting the tendency for perovskite materials to exhibit a ferroelectric distortion; this is achieved via a qualitative trend study in artificial cubic and tetragonal La B O3 perovskites. We choose La as the A cation so as to remove the effects of Bi 6 s hybridization. The lattice instability is identified by the softening of phonon modes in the cubic phase, as well as by the energy lowering associated with a ferroelectric distortion. For the La B O3 series, where B is a d0-d8 cation from the 3 d block, the trend study reveals that increasing the d orbital occupation initially removes the tendency for a polar distortion, as expected. However, for high-spin d5-d7 and d8 cations a strong ferroelectric instability is recovered. This effect is explained in terms of increased pseudo-Jahn-Teller (PJT) p -d vibronic coupling. The PJT effect is described by the competition between a stabilizing force (K0) that favors the cubic phase, and a vibronic term that

  14. Probing the evolution of antiferromagnetism in multiferroics

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, M.; Martin, L.; Scholl, A.; He, Q.; Yu, P.; Yang, C.-H.; Yang, S.; Glans, P.-A.; Valvidares, M.; Huijben, M.; Kortright, J.; Guo,, J.; Chu, Y.-H.; Ramesh, R.

    2010-06-09

    This study delineates the evolution of magnetic order in epitaxial films of the room-temperature multiferroic BiFeO3 system. Using angle- and temperature-dependent dichroic measurements and spectromicroscopy, we have observed that the antiferromagnetic order in the model multiferroic BiFeO3 evolves systematically as a function of thickness and strain. Lattice-mismatch-induced strain is found to break the easy-plane magnetic symmetry of the bulk and leads to an easy axis of magnetization which can be controlled through strain. Understanding the evolution of magnetic structure and how to manipulate the magnetism in this model multiferroic has significant implications for utilization of such magnetoelectric materials in future applications.

  15. Non-collinear magnetism in multiferroic perovskites.

    Science.gov (United States)

    Bousquet, Eric; Cano, Andrés

    2016-03-31

    We present an overview of the current interest in non-collinear magnetism in multiferroic perovskite crystals. We first describe the different microscopic mechanisms giving rise to the non-collinearity of spins in this class of materials. We discuss, in particular, the interplay between non-collinear magnetism and ferroelectric and antiferrodistortive distortions of the perovskite structure, and how this can promote magnetoelectric responses. We then provide a literature survey on non-collinear multiferroic perovskites. We discuss numerous examples of spin cantings driving weak ferromagnetism in transition metal perovskites, and of spin-induced ferroelectricity as observed in the rare-earth based perovskites. These examples are chosen to best illustrate the fundamental role of non-collinear magnetism in the design of multiferroicity. PMID:26912212

  16. Nanoscale ferroelectrics and multiferroics key processes and characterization issues, and nanoscale effects

    CERN Document Server

    Alguero, Miguel

    2016-01-01

    This book reviews the key issues in processing and characterization of nanoscale ferroelectrics and multiferroics, and provides a comprehensive description of their properties, with an emphasis in differentiating size effects of extrinsic ones like boundary or interface effects. Recently described nanoscale novel phenomena are also addressed. Organized into three parts it addresses key issues in processing (nanostructuring), characterization (of the nanostructured materials) and nanoscale effects. Taking full advantage of the synergies between nanoscale ferroelectrics and multiferroics, it covers materials nanostructured at all levels, from ceramic technologies like ferroelectric nanopowders, bulk nanostructured ceramics and thick films, and magnetoelectric nanocomposites, to thin films, either polycrystalline layer heterostructures or epitaxial systems, and to nanoscale free standing objects with specific geometries, such as nanowires and tubes at different levels of development. The book is developed from t...

  17. Preparation and Characterization of Multiferroic La0.7Sr0.3MnO3/PMN-PT Composite Thin Films%多铁性La0.7Sr0.3MnO3/PMN-PT复合薄膜的制备及表征

    Institute of Scientific and Technical Information of China (English)

    苟喜成; 冯明; 刘鑫鑫; 李海波

    2012-01-01

    Multiferroic La0.7Sr0.3MnO3/PMN-PT(LSMO/PMN-PT) Composite films were prepared on Pt/Ti/SiO2/Si substrate via sol-gel spin-coating method.The structure,surface topography,ferroelectric and magnetic properties were characterized by X-ray diffraction(XRD),atomic force microscope(AFM),ferroelectric tester and vibrating sample magnetometer(VSM).The results show that all the XRD peaks corresponding to LSMO and PMN-PT compositional phases,and there exists no chemical reaction or phase diffusion between the LSMO and PMN-PT phases after annealing at 750 ℃.AFM investigation shows that the films have a smooth surface with densely packed uniform grains.The composite thin films exhibit evident ferroelectric and ferromagnetic properties.%采用溶胶-凝胶法在Pt/Ti/SiO2/Si基片上制备了La0.7Sr0.3MnO3/PMN-PT(LSMO/PMN-PT)复合薄膜,利用X射线衍射(XRD)、原子力显微镜(AFM)、铁电性能综合测试仪、振动样品磁强计(VSM)对样品的结构、表面形貌以及铁电性能、磁性进行了分析.结果表明,LSMO/PMN–PT复合薄膜750℃退火处理后,所有X射线衍射峰均为样品特征峰,无扩散现象,没有新相生成;薄膜表面平整、致密、颗粒分布均匀;复合薄膜表现出了明显的铁电和铁磁性能.

  18. Multiferroic properties of Pb{sub 0.90}Sr{sub 0.10}TiO{sub 3}-CoFe{sub 2}O{sub 4} nanostructured bilayered thin film

    Energy Technology Data Exchange (ETDEWEB)

    Bala, Kanchan, E-mail: bala.kanchan1987@gmail.com; Kotnala, R. K. [National Physical Laboratory, New Delhi (India); Negi, N. S. [Department of Physics Himachal Pradesh University Shimla-171005 India (India)

    2015-05-15

    Pb{sub 0.90}Sr{sub 0.10}TiO{sub 3}-CoFe{sub 2}O{sub 4}(PST10-CFO) nanostructured bilayered thin film were grown on Si (100) substrate by using metallo-organic decomposition chemical route and spin coating technique. Results show that PST (pervoskite structure) and CFO (spinel) phase coexist in the bilayered thin films, annealed at 650°C for 2hr and no obvious impurity phase can be detected. The structural, surface morphology and micro structural properties were confirmed by X-Ray diffraction (XRD), atomic force microscope (AFM) respectively. Excellent ferroelectric behavior at different voltage was observed, with two platinum electrodes only at surface of the bilayer thin film. A room temperature ferromagnetic behavior was observed in the bilayered Pb{sub 0.90}Sr{sub 0.10}TiO{sub 3}-CoFe{sub 2}O{sub 4} nanostructured thin film. The saturation magnetization and variation in coercivity value of the bilayer thin film is lower than that of the pure CFO film in the presence of non ferromagnetic PST layer which is the attributed that the significant coupling between the two phases.

  19. NMR study of multiferroic iron niobate perovskites

    Czech Academy of Sciences Publication Activity Database

    Kouřil, K.; Chlan, V.; Štěpánková, H.; Řezníček, R.; Laguta, Valentyn; Raevski, I. P.

    Warszawa : Polish Academy of Sciences, 2015, s. 234-236. ISSN 0587-4246. [The European Conference PHYSICS OF MAGNETISM 2014/PM'14/. Poznań (PL), 23.06.2014-27.06.2014] R&D Projects: GA ČR GA13-11473S Institutional support: RVO:68378271 Keywords : multiferroics * magnetism * NMR Subject RIV: BM - Solid Matter Physics ; Magnetism

  20. Dynamic investigations of multiferroics: Terahertz and beyond

    Energy Technology Data Exchange (ETDEWEB)

    Talbayev, D; Trugman, S A; Balatsky, A V; Taylor, A J [Center for Integrated Nanotechnologies, MS K771, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); LaForge, A D; Basov, D N [Department of Physics University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (United States); Hur, N [Department of Physics, Inha University, Incheon 402-751 (Korea, Republic of); Kimura, T [Division of Materials Physics, Graduate School of Engineering Science, Osaka University Toyonaka, Osaka 560-8531 (Japan); Averitt, R D, E-mail: raveritt@physics.bu.ed, E-mail: diyar@lanl.go [Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, MA 02215 (United States)

    2009-02-01

    We overview our recent studies of the electrodynamic response of multiferroic compounds. We report results of magnetic dynamics in multiferroic hexagonal manganite HoMnO{sub 3} by far-infrared spectroscopy in a magnetic field. Our results provide insight into the ferromagnetic nature of the rare-earth/Mn exchange that enables the electric-field control of magnetism in HoMnO{sub 3}. In the multiferroic Ba{sub 0.6}Sr{sub 1.4}Zn{sub 2}Fe{sub 12}O{sub 22} we have observed a magnetic resonance using time domain pump-probe reflectance spectroscopy revealing the importance of the dynamic magnetoelectric effect which is a modulation of the dielectric tensor by magnetization precession. Our results highlight that magneto-electric dynamics manifest from the far-infrared through the visible and that both time-integrated and time-resolved spectroscopy are important tools in elucidating the microscopic properties of multiferroics.

  1. Multiferroic materials and magnetoelectric physics: symmetry, entanglement, excitation, and topology

    OpenAIRE

    Dong, Shuai; Liu, Jun-Ming; Cheong, Sang-Wook; Ren, Zhifeng

    2015-01-01

    Multiferroics are those materials with more than one ferroic order, and magnetoelectricity refers to the mutual coupling between magnetism and electricity. The discipline of multiferroicity has never been so highly active as that in the first decade of the twenty-first century, and it has become one of the hottest disciplines of condensed matter physics and materials science. A series of milestones and steady progress in the past decade have enabled our understanding of multiferroic physics s...

  2. High pressure and multiferroics materials: a happy marriage

    Directory of Open Access Journals (Sweden)

    Edmondo Gilioli

    2014-11-01

    Full Text Available The community of material scientists is strongly committed to the research area of multiferroic materials, both for the understanding of the complex mechanisms supporting the multiferroism and for the fabrication of new compounds, potentially suitable for technological applications. The use of high pressure is a powerful tool in synthesizing new multiferroic, in particular magneto-electric phases, where the pressure stabilization of otherwise unstable perovskite-based structural distortions may lead to promising novel metastable compounds. The in situ investigation of the high-pressure behavior of multiferroic materials has provided insight into the complex interplay between magnetic and electronic properties and the coupling to structural instabilities.

  3. Continuous Magnetoelectric Control in Multiferroic DyMnO3 Films with Twin-like Domains

    Science.gov (United States)

    Lu, Chengliang; Deniz, Hakan; Li, Xiang; Liu, Jun-Ming; Cheong, Sang-Wook

    2016-02-01

    The magnetic control of ferroelectric polarization is currently a central topic in the multiferroic researches, owing to the related gigantic magnetoelectric coupling and fascinating physics. Although a bunch of novel magnetoelectric effect have been discovered in multiferroics of magnetic origin, the manipulation of polarization was found to be fundamentally determined by the microscopic origin in a certain multiferroic phase, hindering the development of unusual magnetoelectric control. Here, we report emergent magnetoelectric control in DyMnO3/Nb:SrTiO3 (001) films showing twin-like domain structure. Our results demonstrate interesting magnetically induced partial switch of polarization due to the coexistence of polarizations along both the a-axis and c-axis enabled by the twin-like domain structure in DyMnO3 films, despite the polarization-switch was conventionally believed to be a one-step event in the bulk counterpart. Moreover, a continuous and periodic control of macroscopic polarization by an in-plane rotating magnetic field is evidenced in the thin films. This distinctive magnetic manipulation of polarization is the consequence of the cooperative action of the twin-like domains and the dual magnetic origin of polarization, which promises additional applications using the magnetic control of ferroelectricity.

  4. Dispersion characteristics of spin-electromagnetic waves in planar multiferroic structures

    International Nuclear Information System (INIS)

    A method of approximate boundary conditions is used to derive dispersion relations for spin-electromagnetic waves (SEWs) propagating in thin ferrite films and in multiferroic layered structures. A high accuracy of this method is proven. It was shown that the spin-electromagnetic wave propagating in the structure composed of a thin ferrite film, a thin ferroelectric film, and a slot transmission line is formed as a result of hybridization of the surface spin wave in the ferrite film and the electromagnetic wave in the slot-line. The structure demonstrates dual electric and magnetic field tunability of the SEW spectrum. The electric field tunability is provided by the thin ferroelectric film. Its efficiency increases with an increase in the thicknesses of the ferrite and ferroelectric films and with a decrease in the slot-line gap width. The theory is confirmed by experimental data

  5. Dispersion characteristics of spin-electromagnetic waves in planar multiferroic structures

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, Andrey A.; Ustinov, Alexey B. [Department of Physical Electronics and Technology, St. Petersburg Electrotechnical University, St. Petersburg 197376 (Russian Federation); Department of Mathematics and Physics, Lappeenranta University of Technology, Lappeenranta 53850 (Finland); Vitko, Vitaliy V.; Semenov, Alexander A.; Mironenko, Igor G. [Department of Physical Electronics and Technology, St. Petersburg Electrotechnical University, St. Petersburg 197376 (Russian Federation); Belyavskiy, Pavel Yu.; Kalinikos, Boris A. [Department of Physical Electronics and Technology, St. Petersburg Electrotechnical University, St. Petersburg 197376 (Russian Federation); International Laboratory “MultiferrLab,” ITMO University, St. Petersburg 197101 (Russian Federation); Stashkevich, Andrey A. [International Laboratory “MultiferrLab,” ITMO University, St. Petersburg 197101 (Russian Federation); LSPM (CNRS-UPR 3407), Université Paris 13, Sorbonne Paris Cité, 93430 Villetaneuse (France); Lähderanta, E. [Department of Mathematics and Physics, Lappeenranta University of Technology, Lappeenranta 53850 (Finland)

    2015-11-14

    A method of approximate boundary conditions is used to derive dispersion relations for spin-electromagnetic waves (SEWs) propagating in thin ferrite films and in multiferroic layered structures. A high accuracy of this method is proven. It was shown that the spin-electromagnetic wave propagating in the structure composed of a thin ferrite film, a thin ferroelectric film, and a slot transmission line is formed as a result of hybridization of the surface spin wave in the ferrite film and the electromagnetic wave in the slot-line. The structure demonstrates dual electric and magnetic field tunability of the SEW spectrum. The electric field tunability is provided by the thin ferroelectric film. Its efficiency increases with an increase in the thicknesses of the ferrite and ferroelectric films and with a decrease in the slot-line gap width. The theory is confirmed by experimental data.

  6. Epitaxial growth and magnetoelectric relaxor behavior in multiferroic 0.8Pb(Fe1/2Nb1/2)O3-0.2Pb(Mg1/2W1/2)O3 thin films

    OpenAIRE

    Peng, Wei; Lemée, N.; Dellis, J. -L.; Shvartsman, V. V.; Borisov, P.; Kleemann, W.; Trontelj, Z.; Holc, J.; Kosec, M.; Blinc, R.; Karkut, M.G.

    2009-01-01

    We present electric and magnetic properties of 0.8Pb(Fe1/2Nb1/2)O3-0.2Pb(Mg1/2W1/2)O3 films epitaxially grown on (001) SrTiO3 substrates using pulsed laser deposition. A narrow deposition window around 710 oC and 0.2 mbar has been identified to achieve epitaxial single-phase thin films. A typical Vogel-Fulcher relaxor-like dielectric and magnetic susceptibility dispersion is observed, suggesting magnetoelectric relaxor behavior in these films similar to the bulk. We determine a magnetic clust...

  7. Fabrication and properties of multiferroic nanocomposite films

    KAUST Repository

    Al-Nassar, Mohammed Y.

    2015-01-01

    A new type of multiferroic polymer nanocomposite is presented, which exhibits excellent ferromagnetism and ferroelectricity simultaneously at room temperature. The multiferroic nanocomposite consists of a ferroelectric copolymer poly(vinylindene fluoride-trifluoroethylene) [P(VDF-TrFE)] and high aspect ratio ferromagnetic nickel (Ni) nanowires (NWs), which were grown inside anodic aluminum oxide membranes. The fabrication of nanocomposite films with Ni NWs embedded in P(VDF-TrFE) has been successfully carried out via a simple low-temperature spin-coating technique. Structural, ferromagnetic, and ferroelectric properties of the developed nanocomposite have been investigated. The remanent and saturation polarization as well as the coercive field of the ferroelectric phase are slightly affected by the incorporation of the NWs as well as the thickness of the films. While the former two decrease, the last increases by adding the NWs or increasing the thickness. The ferromagnetic properties of the nanocomposite films are found to be isotropic.

  8. Tuning the atomic and domain structure of epitaxial films of multiferroic BiFeO3

    OpenAIRE

    Daumont, C. J. M.; Farokhipoor, S.; Ferri, A; Wojdel, J. C.; Iniguez, Jorge; Kooi, B. J.; Noheda, Beatriz; Wojdeł, J.C.

    2010-01-01

    Recent works have shown that the domain walls of room-temperature multiferroic BiFeO3 (BFO) thin films can display distinct and promising functionalities. It is thus important to understand the mechanisms underlying domain formation in these films. High-resolution x-ray diffraction and piezoforce microscopy, combined with first-principles simulations, have allowed us to characterize both the atomic and domain structure of BFO films grown under compressive strain on (001)-SrTiO3, as a function...

  9. Pyroxenes: a new class of multiferroics

    International Nuclear Information System (INIS)

    Pyroxenes with the general formula AMSi2O6 (A = mono- or divalent metal, M = di- or trivalent metal) are shown to be a new class of multiferroic materials. In particular, we have found so far that NaFeSi2O6 becomes ferroelectric in a magnetically ordered state below ∼6 K. Similarly, magnetically driven ferroelectricity is also detected in the Li homologues, LiFeSi2O6 (TC∼18 K) and LiCrSi2O6 (TC∼11 K). In all these monoclinic systems the electric polarization can be strongly modified by magnetic fields. Measurements of magnetic susceptibility, pyroelectric current and dielectric constants (and their dependence on magnetic field) are performed using a natural crystal of aegirine (NaFeSi2O6) and synthetic crystals of LiFeSi2O6 and LiCrSi2O6 grown from melt solution. For NaFeSi2O6 a temperature versus magnetic field phase diagram is proposed. Exchange constants are computed on the basis of ab initio band structure calculations. The possibility of a spiral magnetic structure caused by frustration to be the reason for the origin of the multiferroic behaviour is discussed. We propose that other pyroxenes may also be multiferroic, and that the versatility of this family offers an exceptional opportunity to study general conditions for and mechanisms of magnetically driven ferroelectricity. (fast track communication)

  10. Multicaloric effect in bi-layer multiferroic composites

    Science.gov (United States)

    Vopson, M. M.; Zhou, D.; Caruntu, G.

    2015-11-01

    The multicaloric effect was theoretically proposed in 2012 and, despite numerous follow up studies, the effect still awaits experimental confirmation. The main limitation is the fact that the multicaloric effect is only observed at a temperature equal to the transition temperature of the magnetic and electric phases coexisting within a multiferroic (MF) (i.e., T ≈ Tcm ≈ Tce). Such condition is hard to fulfill in single phase MFs and a solution is to develop suitable composite MF materials. Here, we examine the multicaloric effect in a bi-layer laminated composite MF in order to determine the optimal design parameters for best caloric response. We show that magnetically induced multicaloric effect requires magnetic component of heat capacity smaller than that of the electric phase, while the layer thickness of the magnetic phase must be at least 5 times the thickness of the electric phase. The electrically induced multicaloric effect requires the magnetic layer to be 10% of the electric phase thickness, while its heat capacity must be larger than that of the electric phase. These selection rules are generally applicable to bulk as well as thin film MF composites for optimal multicaloric effect.

  11. Multicaloric effect in bi-layer multiferroic composites

    Energy Technology Data Exchange (ETDEWEB)

    Vopson, M. M., E-mail: melvin.vopson@port.ac.uk [Faculty of Science, University of Portsmouth, Portsmouth PO1 3QL (United Kingdom); Zhou, D. [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Caruntu, G. [Department of Chemistry and Biochemistry, Central Michigan University, Mount Pleasant, Michigan 48858 (United States)

    2015-11-02

    The multicaloric effect was theoretically proposed in 2012 and, despite numerous follow up studies, the effect still awaits experimental confirmation. The main limitation is the fact that the multicaloric effect is only observed at a temperature equal to the transition temperature of the magnetic and electric phases coexisting within a multiferroic (MF) (i.e., T ≈ T{sub c}{sup m} ≈ T{sub c}{sup e}). Such condition is hard to fulfill in single phase MFs and a solution is to develop suitable composite MF materials. Here, we examine the multicaloric effect in a bi-layer laminated composite MF in order to determine the optimal design parameters for best caloric response. We show that magnetically induced multicaloric effect requires magnetic component of heat capacity smaller than that of the electric phase, while the layer thickness of the magnetic phase must be at least 5 times the thickness of the electric phase. The electrically induced multicaloric effect requires the magnetic layer to be 10% of the electric phase thickness, while its heat capacity must be larger than that of the electric phase. These selection rules are generally applicable to bulk as well as thin film MF composites for optimal multicaloric effect.

  12. Spin excitations in multiferroics and frustrated magnets

    International Nuclear Information System (INIS)

    Inelastic neutron scattering (INS) is still the leading experimental probe of the spin dynamics of magnetic materials: It is not restricted to zero momentum transfer as optical spectroscopy is, and retains an order of magnitude better resolution than resonant inelastic X-ray scattering. Whilst it has been displaced by inelastic X-ray scattering as the technique of choice to measure phonon dispersion, it still retains a role in systems, such as multiferroics, where the symmetry allows an appreciable magnon-phonon coupling. As the theory underpinning the neutron-matter interaction is well understood, one can model quantitatively not only the excitation energies and dispersions, but also the intensities of magnons, phonons and hybrid modes, given a good model of the underlying system Hamiltonian, allowing the parameters of such models, be it exchange interactions, force constants or spinlattice couplings to be extracted. As examples of this type of work, we will discuss measurements of the magnon spectra by INS in the room temperature multiferroic compoung BiFeO3, and magnon-magnon and magnon-phonon interactions in the hexagonal RMnO3 family. Finally, whilst in the past the computational machinery required to carry out these analysis have been relatively inaccessible forcing the experimentalist to devote effort into writing her own code, several open-source programs have become available recently which may allow INS to become a more standard and widely used technique, so we will conclude with an overview of these software.

  13. Multiferroic Iron Oxide Thin Films at Room-Temperature

    OpenAIRE

    Gich, Marti; Fina, Ignasi; Morelli, Alessio; Sanchez, Florencio; Alexe, Marin; Gazquez, Jaume; Fontcuberta, Josep; Roig, Anna

    2014-01-01

    In spite of being highly relevant for the development of a new generation of information storage devices, not many single-phase materials displaying magnetic and ferroelectric orders above room temperature are known. Moreover, these uncommon materials typically display insignificant values of the remanent moment in one of the ferroic orders or are complex multicomponent oxides which will be very challenging to integrate in devices. Here we report on the strategy to stabilize the metastable ep...

  14. Polycrystalline ferroelectric or multiferroic oxide articles on biaxially textured substrates and methods for making same

    Science.gov (United States)

    Goyal, Amit; Shin, Junsoo

    2015-03-31

    A polycrystalline ferroelectric and/or multiferroic oxide article includes a substrate having a biaxially textured surface; at least one biaxially textured buffer layer supported by the substrate; and a biaxially textured ferroelectric or multiferroic oxide layer supported by the buffer layer. Methods for making polycrystalline ferroelectric and/or multiferroic oxide articles are also disclosed.

  15. A concept for a magnetic field detector underpinned by the nonlinear dynamics of coupled multiferroic devices

    International Nuclear Information System (INIS)

    Multiferroic (MF) composites, in which magnetic and ferroelectric orders coexist, represent a very attractive class of materials with promising applications in areas, such as spintronics, memories, and sensors. One of the most important multiferroics is the perovskite phase of bismuth ferrite, which exhibits weak magnetoelectric properties at room temperature; its properties can be enhanced by doping with other elements such as dysprosium. A recent paper has demonstrated that a thin film of Bi0.7Dy0.3FeO3 shows good magnetoelectric coupling. In separate work it has been shown that a carefully crafted ring connection of N (N odd and N ≥ 3) ferroelectric capacitors yields, past a critical point, nonlinear oscillations that can be exploited for electric (E) field sensing. These two results represent the starting point of our work. In this paper the (electrical) hysteresis, experimentally measured in the MF material Bi0.7Dy0.3FeO3, is characterized with the applied magnetic field (B) taken as a control parameter. This yields a “blueprint” for a magnetic (B) field sensor: a ring-oscillator coupling of N = 3 Sawyer-Tower circuits each underpinned by a mutliferroic element. In this configuration, the changes induced in the ferroelectric behavior by the external or “target” B-field are quantified, thus providing a pathway for very low power and high sensitivity B-field sensing

  16. Structure-Dependent Mechanical Properties of ALD-Grown Nanocrystalline BiFeO3 Multiferroics

    Directory of Open Access Journals (Sweden)

    Anna Majtyka

    2016-01-01

    Full Text Available The present paper pertains to mechanical properties and structure of nanocrystalline multiferroic BeFiO3 (BFO thin films, grown by atomic layer deposition (ALD on the Si/SiO2/Pt substrate. The usage of sharp-tip-nanoindentation and multiple techniques of structure examination, namely, grazing incidence X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectrometry, enabled us to detect changes in elastic properties (95 GPa≤E≤118 GPa and hardness (4.50 GPa≤H≤7.96 GPa of BFO after stages of annealing and observe their relation to the material’s structural evolution. Our experiments point towards an increase in structural homogeneity of the samples annealed for a longer time. To our best knowledge, the present report constitutes the first disclosure of nanoindentation mechanical characteristics of ALD-fabricated BeFiO3, providing a new insight into the phenomena that accompany structure formation and development of nanocrystalline multiferroics. We believe that our systematic characterization of the BFO layers carried out at consecutive stages of their deposition provides pertinent information which is needed to control and optimize its ALD fabrication.

  17. Spin dynamics in driven composite multiferroics

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zidong, E-mail: Zidong.Wang@auckland.ac.nz; Grimson, Malcolm J. [Department of Physics, The University of Auckland, Auckland 1010 (New Zealand)

    2015-09-28

    A spin dynamics approach has been used to study the behavior of the magnetic spins and the electric pseudo-spins in a 1-D composite multiferroic chain with a linear magneto-electric coupling at the interface. The response is investigated with either external magnetic or electric fields driving the system. The spin dynamics is based on the Landau-Lifshitz-Gilbert equation. A Gaussian white noise is later added into the dynamic process to include the thermal effects. The interface requires a closer inspection of the magneto-electric effects. Thus, we construct a 2-D ladder model to describe the behavior of the magnetic spins and the electric pseudo-spins with different magneto-electric couplings.

  18. Spin polarization of excitons in organic multiferroic composites

    Science.gov (United States)

    Han, Shixuan; Yang, Liu; Gao, Kun; Xie, Shijie; Qin, Wei; Ren, Shenqiang

    2016-01-01

    Recently, the discovery of room temperature magnetoelectricity in organic charge transfer complexes has reignited interest in the multiferroic field. The solution processed, large-area and low cost organic semiconductor materials offer new possibilities for the functional all organic multiferroic devices. Here we report the spin polarization of excitons and charge transfer states in organic charge transfer composites by using extended Su-Schrieffer-Heeger model including Coulomb interaction and spin-flip effect. With the consideration of spin polarization, we suggest a possible mechanism for the origin of excited ferromagnetism. PMID:27334680

  19. Ordered arrays of multiferroic epitaxial nanostructures

    Directory of Open Access Journals (Sweden)

    Ionela Vrejoiu

    2011-10-01

    Full Text Available Epitaxial heterostructures combining ferroelectric (FE and ferromagnetic (FiM oxides are a possible route to explore coupling mechanisms between the two independent order parameters, polarization and magnetization of the component phases. We report on the fabrication and properties of arrays of hybrid epitaxial nanostructures of FiM NiFe2O4 (NFO and FE PbZr0.52Ti0.48O3 or PbZr0.2Ti0.8O3, with large range order and lateral dimensions from 200 nm to 1 micron. Methods : The structures were fabricated by pulsed-laser deposition. High resolution transmission electron microscopy and high angle annular dark-field scanning transmission electron microscopy were employed to investigate the microstructure and the epitaxial growth of the structures. Room temperature ferroelectric and ferrimagnetic domains of the heterostructures were imaged by piezoresponse force microscopy (PFM and magnetic force microscopy (MFM, respectively. Results : PFM and MFM investigations proved that the hybrid epitaxial nanostructures show ferroelectric and magnetic order at room temperature. Dielectric effects occurring after repeated switching of the polarization in large planar capacitors, comprising ferrimagnetic NiFe2O4 dots embedded in ferroelectric PbZr0.52Ti0.48O3 matrix, were studied. Conclusion : These hybrid multiferroic structures with clean and well defined epitaxial interfaces hold promise for reliable investigations of magnetoelectric coupling between the ferrimagnetic / magnetostrictive and ferroelectric / piezoelectric phases.

  20. Magnetization Reversal by Out-of-plane Voltage in BiFeO3-based Multiferroic Heterostructures.

    Science.gov (United States)

    Wang, J J; Hu, J M; Peng, Ren-Ci; Gao, Y; Shen, Y; Chen, L Q; Nan, C W

    2015-01-01

    Voltage controlled 180° magnetization reversal has been achieved in BiFeO3-based multiferroic heterostructures, which is promising for the future development of low-power spintronic devices. However, all existing reports involve the use of an in-plane voltage that is unfavorable for practical device applications. Here, we investigate, using phase-field simulations, the out-of-plane (i.e., perpendicular to heterostructures) voltage controlled magnetism in heterostructures consisting of CoFe nanodots and (110) BiFeO3 thin film or island. It is predicted that the in-plane component of the canted magnetic moment at the CoFe/BiFeO3 interface can be reversed repeatedly by applying a perpendicular voltage across the bottom (110) BiFeO3 thin film, which further leads to an in-plane magnetization reversal in the overlaying CoFe nanodot. The non-volatility of such perpendicular voltage controlled magnetization reversal can be achieved by etching the continuous BiFeO3 film into isolated nanoislands with the same in-plane sizes as the CoFe nanodot. The findings would provide general guidelines for future experimental and engineering efforts on developing the electric-field controlled spintronic devices with BiFeO3-based multiferroic heterostructures. PMID:25995062

  1. James C. McGroddy Prize Talk: Controlling and Manipulating Ferromagnetism with an Electric Field Using Multiferroic Oxide Heterostructures

    Science.gov (United States)

    Ramesh, R.

    2010-03-01

    Complex perovskite oxides exhibit a rich spectrum of functional responses, including magnetism, ferroelectricity, highly correlated electron behavior, superconductivity, etc. The basic materials physics of such materials provide the ideal playground for interdisciplinary scientific exploration. Over the past decade we have been exploring the science of such materials (for example, colossal magnetoresistance, ferroelectricity, etc) in thin film form by creating epitaxial heterostructures and nanostructures. Among the large number of materials systems, there exists a small set of materials which exhibit multiple order parameters; these are known as multiferroics. Using our work in the field of ferroelectric and ferromagnetic oxides as the background, we are now exploring such materials, as epitaxial thin films as well as nanostructures. A particularly interesting problem is that related to electric field control and manipulation of ferromagnetism. In this talk I will describe to you some aspects of such materials as well as the scientific and technological excitement in this field. Finally I will share my ideas on the most exciting open problems and emerging directions in multiferroics and beyond.

  2. Anomalous Electronic Anisotropy Triggered by Ferroelastic Coupling in Multiferroic Heterostructures.

    Science.gov (United States)

    Ju, Changcheng; Yang, Jan-Chi; Luo, Cheng; Shafer, Padraic; Liu, Heng-Jui; Huang, Yen-Lin; Kuo, Ho-Hung; Xue, Fei; Luo, Chih-Wei; He, Qing; Yu, Pu; Arenholz, Elke; Chen, Long-Qing; Zhu, Jinsong; Lu, Xiaomei; Chu, Ying-Hao

    2016-02-01

    The ferroelastic strain coupling in multiferroic heterostructures is explored aiming at novel physical effects and fascinating functionality. Ferroelastic domain walls in manganites induced by a stripe BiFeO3 template can modulate the electronic transfer and sufficiently block the magnetic ordering, creating a vast anisotropy. The findings suggest the great importance of ferroelastic strain engineering in material modifications. PMID:26640119

  3. Processing and Characterization of Multiferroic Bi-relaxors

    OpenAIRE

    Kumar, Ashok; Katiyar, R. S.; Scott, J F

    2010-01-01

    We compare chemical solution deposition (CSD), and pulsed-laser-deposition (PLD), specimens of the new room-temperature, single-phase, multiferroic magnetoelectric, [PbFe2/3W1/3O3]x[PbZr0.53Ti0.47O3]1-x (PZTFWx ~ 0.40

  4. Large elasto-optic effect and reversible electrochromism in multiferroic BiFeO3.

    Science.gov (United States)

    Sando, D; Yang, Yurong; Bousquet, E; Carrétéro, C; Garcia, V; Fusil, S; Dolfi, D; Barthélémy, A; Ghosez, Ph; Bellaiche, L; Bibes, M

    2016-01-01

    The control of optical fields is usually achieved through the electro-optic or acousto-optic effect in single-crystal ferroelectric or polar compounds such as LiNbO3 or quartz. In recent years, tremendous progress has been made in ferroelectric oxide thin film technology-a field which is now a strong driving force in areas such as electronics, spintronics and photovoltaics. Here, we apply epitaxial strain engineering to tune the optical response of BiFeO3 thin films, and find a very large variation of the optical index with strain, corresponding to an effective elasto-optic coefficient larger than that of quartz. We observe a concomitant strain-driven variation in light absorption-reminiscent of piezochromism-which we show can be manipulated by an electric field. This constitutes an electrochromic effect that is reversible, remanent and not driven by defects. These findings broaden the potential of multiferroics towards photonics and thin film acousto-optic devices, and suggest exciting device opportunities arising from the coupling of ferroic, piezoelectric and optical responses. PMID:26923332

  5. Large elasto-optic effect and reversible electrochromism in multiferroic BiFeO3

    Science.gov (United States)

    Sando, D.; Yang, Yurong; Bousquet, E.; Carrétéro, C.; Garcia, V.; Fusil, S.; Dolfi, D.; Barthélémy, A.; Ghosez, Ph.; Bellaiche, L.; Bibes, M.

    2016-02-01

    The control of optical fields is usually achieved through the electro-optic or acousto-optic effect in single-crystal ferroelectric or polar compounds such as LiNbO3 or quartz. In recent years, tremendous progress has been made in ferroelectric oxide thin film technology--a field which is now a strong driving force in areas such as electronics, spintronics and photovoltaics. Here, we apply epitaxial strain engineering to tune the optical response of BiFeO3 thin films, and find a very large variation of the optical index with strain, corresponding to an effective elasto-optic coefficient larger than that of quartz. We observe a concomitant strain-driven variation in light absorption--reminiscent of piezochromism--which we show can be manipulated by an electric field. This constitutes an electrochromic effect that is reversible, remanent and not driven by defects. These findings broaden the potential of multiferroics towards photonics and thin film acousto-optic devices, and suggest exciting device opportunities arising from the coupling of ferroic, piezoelectric and optical responses.

  6. Challenges and opportunities for multi-functional oxide thin films for voltage tunable radio frequency/microwave components

    Energy Technology Data Exchange (ETDEWEB)

    Subramanyam, Guru, E-mail: gsubramanyam1@udayton.edu [Department of Electrical and Computer Engineering, University of Dayton, Dayton, Ohio 45469 (United States); Cole, M. W., E-mail: melanie.w.cole.civ@mail.mil [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, Maryland 21005 (United States); Sun, Nian X. [Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts 02115 (United States); Kalkur, Thottam S. [Department of Electrical and Computer Engineering, University of Colorado, Colorado Springs, Colorado 80918 (United States); Sbrockey, Nick M.; Tompa, Gary S. [Structured Materials Industries, Inc., Piscataway, New Jersey 08854 (United States); Guo, Xiaomei [Boston Applied Technologies, Inc., Woburn, Massachusetts 01801 (United States); Chen, Chonglin [Department of Physics and Astronomy, University of Texas, San Antonio, Texas 78249 (United States); Alpay, S. P.; Rossetti, G. A. [Institute of Materials Science and Materials Science and Engineering Program, University of Connecticut, Storrs, Connecticut 06269 (United States); Dayal, Kaushik [Mechanics, Materials and Computing, Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States); Chen, Long-Qing [Department of Materials Science and Engineering, Penn State University, University Park, Pennsylvania 16802 (United States); Schlom, Darrell G. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States)

    2013-11-21

    There has been significant progress on the fundamental science and technological applications of complex oxides and multiferroics. Among complex oxide thin films, barium strontium titanate (BST) has become the material of choice for room-temperature-based voltage-tunable dielectric thin films, due to its large dielectric tunability and low microwave loss at room temperature. BST thin film varactor technology based reconfigurable radio frequency (RF)/microwave components have been demonstrated with the potential to lower the size, weight, and power needs of a future generation of communication and radar systems. Low-power multiferroic devices have also been recently demonstrated. Strong magneto-electric coupling has also been demonstrated in different multiferroic heterostructures, which show giant voltage control of the ferromagnetic resonance frequency of more than two octaves. This manuscript reviews recent advances in the processing, and application development for the complex oxides and multiferroics, with the focus on voltage tunable RF/microwave components. The over-arching goal of this review is to provide a synopsis of the current state-of the-art of complex oxide and multiferroic thin film materials and devices, identify technical issues and technical challenges that need to be overcome for successful insertion of the technology for both military and commercial applications, and provide mitigation strategies to address these technical challenges.

  7. Challenges and opportunities for multi-functional oxide thin films for voltage tunable radio frequency/microwave components

    International Nuclear Information System (INIS)

    There has been significant progress on the fundamental science and technological applications of complex oxides and multiferroics. Among complex oxide thin films, barium strontium titanate (BST) has become the material of choice for room-temperature-based voltage-tunable dielectric thin films, due to its large dielectric tunability and low microwave loss at room temperature. BST thin film varactor technology based reconfigurable radio frequency (RF)/microwave components have been demonstrated with the potential to lower the size, weight, and power needs of a future generation of communication and radar systems. Low-power multiferroic devices have also been recently demonstrated. Strong magneto-electric coupling has also been demonstrated in different multiferroic heterostructures, which show giant voltage control of the ferromagnetic resonance frequency of more than two octaves. This manuscript reviews recent advances in the processing, and application development for the complex oxides and multiferroics, with the focus on voltage tunable RF/microwave components. The over-arching goal of this review is to provide a synopsis of the current state-of the-art of complex oxide and multiferroic thin film materials and devices, identify technical issues and technical challenges that need to be overcome for successful insertion of the technology for both military and commercial applications, and provide mitigation strategies to address these technical challenges

  8. Studies of the Transports and Electrical Properties in Multiferroic Tunnel Junction

    Science.gov (United States)

    Barrionuevo Diestra, Danilo; Ortega, Nora; Katiyar, Ram; Sokolov, Andrei

    2014-03-01

    A multiferroic tunnel junction (MFTJ) consists of metal or ferromagnetic electrodes separated by a ferroelectric (FE) or single phase multiferroics barrier. We have studied two different MFTJ configurations: (i) La0.67Sr0.33MnO3 (LSMO)/PbZr0.52Ti0.48O3 (PZT)/LSMO, (ii) Pt/Pb(Zr0.53Ti0.47)0.60 (Fe0.5Ta0.5)0.40 O3 (PTZFT)/LSMO. We have grown ultrathin films of about 3 to 7 nm of PZT on LSMO/(LaAlO3)0.3 (Sr2AlTaO6)0.7 (LSMO/LSAT) (001) substrates using by pulsed laser deposition technique. With similar technique and substrate, we have grown ultrathin films of 4.5 to 6 nm of PZTFT. The x-ray diffraction patterns of the heterostructures show only the (00 l) reflections corresponding to the LSAT substrate, PZT or PZTFT and LSMO layers. The Atomic force microscopy of PZT/LSMO/LSAT and PZTFT/LSMO/LSAT heterostructures shows that the average surface roughness was less than 1 nm. Piezo force microscopy of the ultrathin PZT and PZTFT films shows a clear and reversible out-of-plane phase contrast above +/- 3 V, which indicates the ferroelectric character of those thin films. The Current-Voltage (IV) characteristics of the PZT/LSMO films, with PZT barrier thickness between 7 to 3 nm showed nonlinear IV characteristics indicating tunneling mechanism. The resistance switching behavior was observed from low resistance state to high resistance state and vice versa by sweeping the voltage from negative to positive and back.

  9. Hydrothermal epitaxial multiferroic BiFeO3 thick film by addition of the PVA

    International Nuclear Information System (INIS)

    Graphical abstract: Epitaxial BiFeO3 (BFO) thin films were fabricated on (0 0 1)-oriented single-crystal SrRuO3(SRO)/SrTiO3(STO) structures by PVA-assistant hydrothermal method. The electrical properties observed in BFO (0 0 1) thin films are superior to those of hydrothermal epitaxy reported previously, which indicates PVA plays an important role in fabricating BFO films by using hydrothermal method. Highlights: •We grow BiFeO3 thick film by hydrothermal method. •PVA as assistant agent epitaxially grow BiFeO3 thick film. •The ferroelectric properties of BiFeO3 thick film were measured. •The electrical properties observed in BFO (0 0 1) thin films are superior to those of hydrothermal epitaxy reported previously. -- Abstract: Hydrothermal method is a much simpler method of epitaxial multiferroic BiFeO3 (BFO) film than physical/chemical vapor deposition methods. In this work, epitaxial BFO thin films were fabricated on (0 0 1)-oriented single-crystal SrRuO3(SRO)/SrTiO3(STO) structures by PVA-assistant hydrothermal method. The results of θ–2θ scan, ω scan and reciprocal space mappings (RSMs) measured by synchrotron high resolution X-ray diffraction and high-resolution transmission electron microscopy (HRTEM) suggest that the BFO films have relaxed to a single-phase monoclinic structure. The electrical properties observed in BFO (0 0 1) thin films are superior to those of hydrothermal epitaxy reported previously, which indicates PVA plays an important role in fabricating BFO films by using hydrothermal method

  10. Multiferroic materials for spin-based logic devices

    OpenAIRE

    de Sousa, Rogerio; Moore, Joel E.

    2008-01-01

    Logical devices based on spin waves offer the potential to avoid dissipation mechanisms that limit devices based on either the charge or spin of mobile electrons. Multiferroic magnetoelectrics, which are materials that combine ferroelectric and magnetic order, allow direct switching of magnetic order and thence of spin-wave properties using an applied electric field. The intrinsic coupling between polarization and magnetic moments, generated by strong electronic correlations in these multifer...

  11. Frequency-temperature response of a new multiferroic

    OpenAIRE

    Nawnit Kumar; Sunanda K. Patri; Ram N.P. Choudhary

    2014-01-01

    The frequency dependence of the electrical properties of a new complex multiferroic Bi4Pb2Ti3FeNbO18 at different temperatures was investigated by impedance spectroscopy technique. The impedance spectroscopic data were collected at different frequencies (100Hz–1MHz) and temperatures (25–500 °C). This study provides important information about the effect of grain and grain boundary on microstructures of the materials. The data are presented in the Nyquist plots, from which electrical resist...

  12. Changing Dielectrics into Multiferroics---Alchemy Enabled by Strain

    Science.gov (United States)

    Schlom, Darrell

    2011-03-01

    Ferroelectric ferromagnets are exceedingly rare, fundamentally interesting multiferroic materials. The properties of what few compounds simultaneously exhibit these phenomena pale in comparison to useful ferroelectrics or ferromagnets: their spontaneous polarizations (Ps) or magnetizations (Ms) are smaller by a factor of 1000 or more. The same holds for (magnetic or electric) field-induced multiferroics. Recently, however, Fennie and Rabe proposed a new route to ferroelectric ferromagnets---transforming magnetically ordered insulators that are neither ferroelectric nor ferromagnetic, of which there are many, into ferroelectric ferromagnets using a single control parameter: strain. The system targeted, EuTi O3 , was predicted to simultaneously exhibit strong ferromagnetism (Ms ~ ~ ~7~μB /Eu) and strong ferroelectricity (Ps ~ ~ ~10~ μ C/cm2) under large biaxial compressive strain. These values are orders of magnitude higher than any known ferroelectric ferromagnet and rival the best materials that are solely ferroelectric or ferromagnetic. Hindered by the absence of an appropriate substrate to provide the desired compression, we show 3 both experimentally and theoretically the emergence of a multiferroic state under biaxial tension with the unexpected benefit that even lower misfits are required, thereby enabling higher quality crystalline films. The resulting genesis of a strong ferromagnetic ferroelectric points the way to high temperature manifestations of this spin-phonon coupling mechanism. Our work demonstrates that a single experimental parameter, strain, simultaneously controls multiple order parameters and is a viable alternative tuning parameter to composition for creating multiferroics. C.J. Fennie and K.M. Rabe, Phys. Rev. Lett. 97 (2006) 267602.

  13. Magnetoelectric coupling effects in multiferroic complex oxide composite structures.

    Science.gov (United States)

    Vaz, Carlos A F; Hoffman, Jason; Ahn, Charles H; Ramesh, Ramamoorthy

    2010-07-20

    The study of magnetoelectric materials has recently received renewed interest, in large part stimulated by breakthroughs in the controlled growth of complex materials and by the search for novel materials with functionalities suitable for next generation electronic devices. In this Progress Report, we present an overview of recent developments in the field, with emphasis on magnetoelectric coupling effects in complex oxide multiferroic composite materials. PMID:20414887

  14. Unusual spin glass behaviour in multiferroic yttrium bismuth manganite

    International Nuclear Information System (INIS)

    Multiferroic materials are extensively researched nowadays because they exhibit both ferroelectricity and ferromagnetism simultaneously at room temperature. They find extensive applications in devices such as sensors, field effect transistors and memory devices. Rare Earth based multiferroics have attracted the attention of scientists and engineers because they satisfy some of the essential criterion for exhibiting multiferroicity namely non-centerosymmetry, d0-ness and geometric frustrations. YMnO3 is one of the most extensively studied multiferroic, hexagonal manganite having room temperature ferroelectricity and an A-type antiferromagnetic ordering, below 60 K. A study on the change in magnetic ordering in YMnO3, with Bi3+ substitution at Y3+ sites, is carried out. YBiMnO3 samples (Y1-xBixMnO3, x = 0, 0.1, 0.3) were prepared via soft-chemistry procedures. X-ray Diffraction technique confirms the single phasic nature. M-H curves at room temperature and below ordering temperature shows marked increase in coercivity with increase in the Bi composition. Zero Field Cooled (ZFC) and Field Cooled (FC) measurements carried out at 25Oe, 50Oe and 200Oe indicate thermal irreversibility with a spin glass like transition at lower fields gradually vanishing at higher fields, In un-doped YMnO3, the transition from paramagnetic to antiferromagnetically ordered state clearly appears in the FC-ZFC curves as a change of slope at 45K while in the Bi doped samples instantly after the irreversibility, a cusp is formed at lower fields in MZFC at ∼ 35K which is a typical characteristic of spin glass system. With increase in Bi percentage, the cusp is shifted from ∼ 35K to 30K. The irreversibility starts at around 45K and gets narrower with increase in Bi percentage, with a considerable decrease in the magnetization values. Plausible reasons for the observed change in magnetization are discussed and the results are presented here. (author)

  15. Ultrafast polarization and magnetization dynamics in a multiferroic GaFeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Matsubara, M; Okamoto, H [Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8562 (Japan); Kaneko, Y; He, J P; Tokura, Y, E-mail: m-matsubara@aist.go.j [Multiferroics Project, ERATO, Japan Science and Technology Agency (JST), ASI, RIKEN, Wako 351-0198 (Japan)

    2009-02-01

    We have investigated the ultrafast dynamical behaviors of the electric polarization and the magnetization in a multiferroic GaFeO{sub 3}. We show that the time-resolved nonlinear optical technique is a powerful tool for the probe of the ultrafast dynamics of multiferroic properties.

  16. Multiferroic properties of nanostructured barium doped bismuth ferrite

    Science.gov (United States)

    El-Desoky, M. M.; Ayoua, M. S.; Mostafa, M. M.; Ahmed, M. A.

    2016-04-01

    Multiferroic nanoparticles of Bi1-xBaxFeO3 (x=0.10, 0.15, 0.20, 0.25 mol%) samples were prepared using conventional solid-state method. The nanostructural, multiferroic properties of the prepared samples was investigated. X-ray diffraction (XRD) patterns show the formation of BiBaFeO3 with single-phase rhombohedral-hexagonal structure. Spin canting or impurity phase could be a probable reason for the origin of ferromagnetism. At room temperature, remnant magnetization increased 18 times more than its initial value. A change in the magnetization is observed around 742-833 K. Néel temperature (TN) registers an increase of 30 times of Ba-doped BiFeO3 in comparison with undoped BiFeO3. The dielectric properties were affected by the properties of the substitutional ions as well as the crystalline structure of the present samples. Substitution with Ba2+ ions also improved the ferroelectric polarization with remanent polarization of 89 μC/cm2. The simultaneous occurrence of ferromagnetism and ferroelectric hysteresis loops in BiBaFeO3 multiferroic nanoparticles system at room temperature makes it a potential candidate for information storage and spintronics.

  17. Raman phonons in multiferroic FeVO4 crystals

    Science.gov (United States)

    Zhang, An-Min; Liu, Kai; Ji, Jian-Ting; He, Chang-Zhen; Tian, Yong; Jin, Feng; Zhang, Qing-Ming

    2015-12-01

    Multiferroic materials are promising candidates for next-generation multi-functional devices, because of the coexistence of multi-orders and the coupling between the orders. FeVO4 has been confirmed to be a multiferroic compound, since it exhibits both ferroelectricity and antiferromagnetic ordering at low temperatures. In this paper, we have performed careful Raman scattering measurements on high-quality FeVO4 single crystals. The compound has a very rich phonon structure due to its low crystal symmetry (P - 1) and at least 47 Raman-active phonon modes have been resolved in the low and hightemperature spectra. Most of the observed modes are well assigned with aid of first-principles calculations and symmetry analysis. The present study provides an experimental basis for exploring spin-lattice coupling and the mechanism of multiferroicity in FeVO4 Project supported by the National Basic Research Program of China (Grant No. 2012CB921701), the National Natural Science Foundation of China (Grant Nos. 11174367 and 11004243), the China Postdoctoral Science Foundation, the Fundamental Research Funds for the Central Universities, and the Research Funds of Renmin University of China (Grant Nos. 10XNI038, 14XNLF06, and 14XNLQ03).

  18. Evidence of multiferroicity in NdMn2O5

    Science.gov (United States)

    Chattopadhyay, S.; Balédent, V.; Damay, F.; Gukasov, A.; Moshopoulou, E.; Auban-Senzier, P.; Pasquier, C.; André, G.; Porcher, F.; Elkaim, E.; Doubrovsky, C.; Greenblatt, M.; Foury-Leylekian, P.

    2016-03-01

    Recently, R Mn2O5 (R =rare earth, Bi, Y) type multiferroics have drawn considerable attention, because of magnetically induced ferroelectricity along with an extremely large magnetoelectric coupling. Here, we present a detailed study on NdMn2O5 which is a crucial composition between the nonferroelectric PrMn2O5 and ferroelectric SmMn2O5 . We report the results of heat capacity, magnetization, dielectric permittivity, and electric polarization measurements along with an accurate description of the structural and microscopic magnetic properties obtained from high resolution x-ray and neutron diffraction studies. We show that NdMn2O5 is ferroelectric, although the magnitude of polarization is much weaker than that of the other multiferroic members. The direction of the polarization is along the crystallographic b axis and its magnitude can be tuned with the application of a magnetic field. Moreover, unlike the other multiferroic members of this series, ferroelectricity in NdMn2O5 emerges in an incommensurate magnetic state. The present study also provides evidence in support of the influence of the rare-earth size on the magnetoelectric phase diagram.

  19. Preparation and characterization of single-crystal multiferroic nanofiber composites

    International Nuclear Information System (INIS)

    Graphical abstract: One-dimensional single-crystal multiferroic composites composed of PbTiO3 nanofiber-CoFe2O4 nanodot have been prepared for the first time by a facile in situ solid state sintering method. The composites demonstrate ferroelectricity and ferromagnetism as well as strong coupling between them. Highlights: ► 1D single-crystal multiferroic PTO-CFO was prepared via in situ solid state sintering method. ► A simple epitaxial growth relation has been found between the PTO–CFO composites. ► The composites reveal ferroelectricity and ferromagnetism as well as coupling between them. -- Abstract: One-dimensional single-crystal multiferroic composites consisting of PbTiO3 (PTO) nanofiber-CoFe2O4 (CFO) nanodot were prepared using an in situ solid state sintering method, where pre-perovskite PTO nanofibers and CFO nanodots were used as precursors. Structural analyses by using transmission electron microscopy, scanning electron microscopy and X-ray diffraction determined a epitaxial growth relation between the PTO nanofiber and the CFO nanodot. Ferromagnetism and ferroelectricity of the nanofiber composites were investigated by using vibarting sample magnetometer (VSM) and piezoresponse force microscopy (PFM)

  20. Preparation and characterization of single-crystal multiferroic nanofiber composites

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Zhaohui; Xiao, Zhen; Yin, Simin; Mai, Jiangquan; Liu, Zhenya; Xu, Gang; Li, Xiang; Shen, Ge [State Key Lab of Silicon Materials, Department of Material Science and Engineering, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou 310027 (China); Han, Gaorong, E-mail: hgr@zju.edu.cn [State Key Lab of Silicon Materials, Department of Material Science and Engineering, Cyrus Tang Center for Sensor Materials and Applications, Zhejiang University, Hangzhou 310027 (China)

    2013-03-05

    Graphical abstract: One-dimensional single-crystal multiferroic composites composed of PbTiO{sub 3} nanofiber-CoFe{sub 2}O{sub 4} nanodot have been prepared for the first time by a facile in situ solid state sintering method. The composites demonstrate ferroelectricity and ferromagnetism as well as strong coupling between them. Highlights: ► 1D single-crystal multiferroic PTO-CFO was prepared via in situ solid state sintering method. ► A simple epitaxial growth relation has been found between the PTO–CFO composites. ► The composites reveal ferroelectricity and ferromagnetism as well as coupling between them. -- Abstract: One-dimensional single-crystal multiferroic composites consisting of PbTiO{sub 3} (PTO) nanofiber-CoFe{sub 2}O{sub 4} (CFO) nanodot were prepared using an in situ solid state sintering method, where pre-perovskite PTO nanofibers and CFO nanodots were used as precursors. Structural analyses by using transmission electron microscopy, scanning electron microscopy and X-ray diffraction determined a epitaxial growth relation between the PTO nanofiber and the CFO nanodot. Ferromagnetism and ferroelectricity of the nanofiber composites were investigated by using vibarting sample magnetometer (VSM) and piezoresponse force microscopy (PFM)

  1. Nanoscale Control of Exchange Bias with BiFeO3 Thin Films

    NARCIS (Netherlands)

    Martin, Lane W.; Chu, Ying-Hao; Holcomb, Mikel B.; Huijben, Mark; Yu, Pu; Han, Shu-Jen; Lee, Donkoun; Wang, Shan X.; Ramesh, R.

    2008-01-01

    We demonstrate a direct correlation between the domain structure of multiferroic BiFeO3 thin films and exchange bias of Co0.9Fe0.1/BiFeO3 heterostructures. Two distinct types of interactions − an enhancement of the coercive field (exchange enhancement) and an enhancement of the coercive field combin

  2. The induced magnetic and electric fields' paradox leading to multicaloric effects in multiferroics

    Science.gov (United States)

    Vopson, Melvin M.

    2016-04-01

    Magneto-electric effect in multiferroics implies that an applied magnetic field induces an electric polarization change in a multiferroic solid and vice versa, an applied electric field modifies its magnetization. The magneto-electric effect is a powerful feature of multiferroics and has attracted huge interest due to potential technological applications. One such possible application is the multicaloric effect in multiferroics. However, a closer examination of this effect and its derivation leads to a paradox, in which the predicted changes in one of the order phase at a constant applied field are due to the excitation by the same field. Here this apparent paradox is first explained in detail and then solved. Understanding how electric and magnetic fields can be induced in multiferroic materials is an essential tool enabling their theoretical modeling as well as facilitating the introduction of future applications.

  3. Strain-coupled multiferroic model system of magnetic films on piezoelectric PMN-PT(001)

    Energy Technology Data Exchange (ETDEWEB)

    Herklotz, Andreas; Rata, Diana; Boldyreva, Ksenia; Bilani-Zeneli, Orkidia; Dekker, Martina Cornelia; Schultz, Ludwig; Doerr, Kathrin [IFW Dresden (Germany)

    2009-07-01

    In many multiferroic composites the interrelation of magnetic and polar electric properties originates from joined elastic strain of the components. A straightforward model system for quantitative investigations of strain-modulated magnetic properties comprises of magnetic films epitaxially grown on high-strain piezoelectric single crystals. In this work, we report on structural, ferroelectric and elastic properties of Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-PbTiO{sub 3} (PMN-PT) (001) single crystals utilized as thin film substrates for dynamical strain control of up to 0.25% in complex oxide films. A tunable buffer layer system of solid solutions of perovskite-type LaScO{sub 3} and LaAlO{sub 3} has been developed that serves to adjust the in-plane parameter of buffered PMN-PT in a range of several percent. Thus, various as-grown strain states of a given magnetic film can be prepared and studied under reversible strain. First examples for La{sub 1-x}Sr{sub x}BO{sub 3} (B=Co or Mn) films under both statically and dynamically varied biaxial strain will be discussed.

  4. Strain-driven Anisotropy in Multiferroic Composites Probed with Soft X-ray Techniques

    International Nuclear Information System (INIS)

    Full text: Artificial multiferroic systems, in which novel properties emerge from elastic coupling between piezoelectric and magnetostrictive phases, show promise as a route to obtain room temperature magneto-electric coupling. We have used soft X-ray photoemission electron microscopy (X-PEEM) to determine the influence of piezoelectric-ferroelectric BaTiO3 (BTO) on the magnetic properties of magnetostrictive ferrimagnetic CoFe2O4 and NiFe2O4 thin films. Circular and linear dichroism spectromicroscopy gives insight into the magneto-electric interaction in a model system of a BTO substrate with an epitaxial spinel cap layer. An induced dichroism in the ferrimagnetic films is structural in origin and directly corresponds to the ferroelectric domain structure of the BTO substrate as imaged at both the Ti L2,3 edges of BTO and the Fe L2,3 edges of the film. Temperature, angular, and polarization dependent studies reveal this strain-induced effect strongly influences the magnetic anisotropy of individual 250 nm wide magnetic domains of the spinel films. (author)

  5. Spin lattice coupling in multiferroic hexagonal YMnO3

    Indian Academy of Sciences (India)

    Sylvain Petit; Stéphane Pailhès; Xavier Fabrèges; Martine Hennion; Fernande Moussa; Loreynne Pinsard; Louis-Pierre Regnault; Alexander Ivanov

    2008-10-01

    Aiming to shed light on the possible existence of hybrid phonon—magnon excitations in multiferroic manganites, neutron scattering measurements have been un-dertaken at LLB and ILL on the particular case of hexagonal YMnO3. Our experiments focused on a transverse acoustic phonon mode polarized along the ferroelectric axis. The neutron data show that below the magnetic transition, this particular phonon mode splits in two different branches. The upper branch is found to coincide with a spin wave mode. This manifestation of a strong spin-lattice coupling is discussed in terms of a possible hybridization between the two types of elementary excitations, the phonon and magnons.

  6. Ferroelectric control of anisotropic damping in multiferroic tunnel junctions

    Science.gov (United States)

    Wang, Yan; Zhang, Ning; Berakdar, Jamal; Jia, Chenglong

    2015-10-01

    The magnetoelectric effect on nonlocal magnetization dynamics is theoretically investigated in normal-metal/ferroelectric-insulator/ferromagnetic tunnel junctions. In addition to the Rashba spin-orbit interaction (SOI) originating from loss of parity symmetry at the interfaces, the topology of interfacial spiral spins triggered by ferroelectric polarization acts with an effective SOI that is electrically controllable. These spin-dependent interactions result in an anisotropic Gilbert damping with C2 v symmetry. The findings are of a direct relevance for the utilization of composite multiferroics for devices that rely on electrically controlled magnetic switching.

  7. Manifestation of ferroelectromagnetism in multiferroic BiMnO3

    International Nuclear Information System (INIS)

    Multiferroic BiMnO3 with a highly distorted perovskite structure induced by the stereochemically active 6s2 electron lone pairs of Bi3+ was synthesized at a high pressure of 6 GPa. Magnetization, differential scanning calorimetry, dielectric permittivity, and in situ powder x-ray diffraction as a function of temperature were carried out, respectively. In light of comprehensive evaluation, we can conclude that the synthetic BiMnO3 ceramic displays ferromagnetic and ferroelectric orderings simultaneously, i.e., ferroelectromagnetism below its ferromagnetic Curie temperature TM∼100 K

  8. Study of local correlations of magnetic and multiferroic compounds

    CERN Multimedia

    Alves, E J

    We propose to study magnetic and multiferroic strongly correlated electron materials using radioactive nuclear probe techniques, at ISOLDE . Following the strategy of a previous project, IS390, our aim is to provide local and element selective information on some of the mechanisms that rule structural, charge and orbital correlations, electronic and magnetic interactions and the coupling of the associated degrees of freedom. The main technique used is Perturbed Angular Correlations (PAC), which allows combined magnetic and electric hyperfine studies. This study is complemented by the use of conventional characterisation techniques, and the investigation of relevant macroscopic properties.

  9. Multiferroic and magnetoelectric materials – Developments and perspectives

    Directory of Open Access Journals (Sweden)

    Shvartsman V. V.

    2012-06-01

    Full Text Available Multiferroic (MF materials with simultaneous magnetic and electric long range order and occasionally, mutual magnetoelectric (ME coupling, have recently attracted considerable interest. The small linear ME effect has been shown to control spintronic devices very efficiently, e.g. via the classic ME antiferromagnet Cr2O3 using exchange bias. Similar nano-engineering concepts exist also for type-I MF single phase materials, whose magnetic and polar orders have distinct origins like BiFeO3. Strong ME coupling occurs in type-II multiferroics, where ferroelectricity is due to spiral spin order as in TbMnO3. Record high ME response coming close to applicability arises in stress-strain coupled multiphase magnetoelectrics such as PZT/FeBSiC composites. Higher order ME response in disordered systems (“type-III multiferroics” extends the conventional MF scenario toward ME quantum paraelectric and multiglass materials with polarization-induced control of magnetic exchange, as e.g. in EuTiO3, Sr0.98Mn0.02TiO3, and PbFe0.5Nb0.5O3.

  10. Electric-field control of magnetism in multiferroic heterostructures

    Science.gov (United States)

    Zhao, Yonggang; Zhang, Sen; Li, Peisen; Chen, Aitian; Li, Dalai; Yang, Lifeng; Rizwan, S.; Liu, Y.; Xiao, Xia; Wu, Yizheng; Jin, Xiaofeng; Han, Xiufeng; Zhang, Huiyun; Zhu, Meihong

    2015-03-01

    We have studied electric-field control of magnetism in different multiferroic heterostructures, composed of ferromagnetic (FM) and ferroelectric (FE) materials such as Co40Fe40B20(CoFeB)/Pb(Mg1/3Nb2/3)0.7Ti0.3O3(PMN-PT) and magnetic tunnel junctions (MTJ) on PMN-PT, etc. A giant electric-field control of magnetization as well as magnetic anisotropy was observed in a CoFeB/PMN-PT structure at room temperature with a maximum relative magnetization change up to 83 percent and a 90° rotation of the easy axis. In MTJ of CoFeB/AlOx/CoFeB grown on PMN-PT, we demonstrate a reversible, continuous magnetization rotation and manipulation of tunneling magnetoresistance at room temperature by electric fields without the assistance of a magnetic field. These results show the interesting new physics and potential applications of the FM/FE multiferroic heterostructures.

  11. Multiferroic heterostructures for spin filter application - an ab initio study

    CERN Document Server

    Borek, Stephan; Ebert, Hubert; Minár, Ján

    2015-01-01

    Novel imaging spin-filter techniques, which are based on low energy electron diffraction, are currently of high scientific interest. To improve the spin-detection efficiency a variety of new materials have been introduced in recent years. A new class of promising spin-filter materials are represented by multiferroic systems, as both magnetic and electric ordering exist in these materials. We have investigated Fe/BaTiO3(001), which defines a prominent candidate due to its moderate spontaneous polarization, for spin filter applications calculating diffraction patterns for spin polarized electrons incident on the Fe surface. Motivated by the fact that spin polarized low energy electron diffraction is a powerful method for the determination of the properties of surfaces we investigated the influence of switching the BaTiO3 polarization on the exchange and spin orbit scattering as well as on reflectivity and figure of merit. This system obviously offers the possibility to realize a multiferroic spin filter and man...

  12. One-way electromagnetic waveguide using multiferroic Fibonacci superlattices

    Science.gov (United States)

    Tang, Zhenghua; Lei, Dajun; Huang, Jianquan; Jin, Gui; Qiu, Feng; Yan, Wenyan

    2015-12-01

    The multiferroic Fibonacci superlattices (MFSs) are composed of single-phase multiferroic domains with polarization and magnetization according to the rule of Fibonacci sequence. We propose to construct a one-way electromagnetic waveguide by the MFSs. The forbidden band structures of the MFSs for the forward and backward electromagnetic waves are not completely overlapped, and an obvious translation between them occurs around the fixed point ω bar = 1 with broken time-reversal and space inversion symmetries (TRSIS), which indicates the existence of one-way electromagnetic modes in the MFSs. Transmission spectrum is utilized to present this property and to indicate further one-way electromagnetic modes lying within the polaritonic band gap. The maximum forbidden bandwidth (divided by midgap frequency) of 5.4% for the backward electromagnetic wave (BEW) is found, in which the forward electromagnetic wave (FEW) can pass. The functions of one-way propagation modes and polaritonic band gap integrated into the MFSs can miniaturize the one-way photonic devices. The properties can also be applied to construct compact microwave isolators.

  13. Thermodynamics of multicaloric effects in multiferroic materials: application to metamagnetic shape-memory alloys and ferrotoroidics.

    Science.gov (United States)

    Planes, Antoni; Castán, Teresa; Saxena, Avadh

    2016-08-13

    We develop a general thermodynamic framework to investigate multicaloric effects in multiferroic materials. This is applied to the study of both magnetostructural and magnetoelectric multiferroics. Landau models with appropriate interplay between the corresponding ferroic properties (order parameters) are proposed for metamagnetic shape-memory and ferrotoroidic materials, which, respectively, belong to the two classes of multiferroics. For each ferroic property, caloric effects are quantified by the isothermal entropy change induced by the application of the corresponding thermodynamically conjugated field. The multicaloric effect is obtained as a function of the two relevant applied fields in each class of multiferroics. It is further shown that multicaloric effects comprise the corresponding contributions from caloric effects associated with each ferroic property and the cross-contribution arising from the interplay between these ferroic properties.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'. PMID:27402925

  14. James C. McGroddy Prize for New Materials Talk: A theorist's-eye view of multiferroics

    Science.gov (United States)

    Spaldin, Nicola

    2010-03-01

    I will summarize the evolution of the field of multiferroics -- that is materials that show multiple simultaneous ferroic orderings -- since their ``renaissance'' in the late 1990s. In particular, I will illustrate how first-principles electronic structure calculations have contributed to progress in the field, and conversely, how fascinating questions in multiferroics have prompted the development of improved electronic structure methods. Finally I will share my ideas on the most exciting open problems and emerging directions in multiferroics and beyond.

  15. Optical diode effect in the room-temperature multiferroic BiFeO$_3

    OpenAIRE

    Kezsmarki, I.; Nagel, U.; Bordacs, S.; Fishman, R. S.; Lee, J.H.; Yi, H. T.; Cheong, S-W.; Room, T.

    2015-01-01

    Multiferroics permit the magnetic control of the electric polarization and electric control of the magnetization. These static magnetoelectric (ME) effects are of enormous interest: The ability to read and write a magnetic state current-free by an electric voltage would provide a huge technological advantage. Dynamic or optical ME effects are equally interesting because they give rise to unidirectional light propagation as recently observed in low-temperature multiferroics. This phenomenon, i...

  16. Research Update: Electrical manipulation of magnetism through strain-mediated magnetoelectric coupling in multiferroic heterostructures

    Directory of Open Access Journals (Sweden)

    A. T. Chen

    2016-03-01

    Full Text Available Electrical manipulation of magnetism has been a long sought-after goal to realize energy-efficient spintronics. During the past decade, multiferroic materials combining (antiferromagnetic and ferroelectric properties are now drawing much attention and many reports have focused on magnetoelectric coupling effect through strain, charge, or exchange bias. This paper gives an overview of recent progress on electrical manipulation of magnetism through strain-mediated magnetoelectric coupling in multiferroic heterostructures.

  17. Research Update: Electrical manipulation of magnetism through strain-mediated magnetoelectric coupling in multiferroic heterostructures

    Science.gov (United States)

    Chen, A. T.; Zhao, Y. G.

    2016-03-01

    Electrical manipulation of magnetism has been a long sought-after goal to realize energy-efficient spintronics. During the past decade, multiferroic materials combining (anti)ferromagnetic and ferroelectric properties are now drawing much attention and many reports have focused on magnetoelectric coupling effect through strain, charge, or exchange bias. This paper gives an overview of recent progress on electrical manipulation of magnetism through strain-mediated magnetoelectric coupling in multiferroic heterostructures.

  18. Mutual Ferromagnetic-Ferroelectric Coupling in Multiferroic Copper Doped ZnO

    International Nuclear Information System (INIS)

    A mutual ferromagnetic and ferroelectric coupling (multiferroic behavior) in Cu-doped ZnO is demonstrated via deterministic control of Cu doping and defect engineering. The coexistence of multivalence Cu ions and oxygen vacancies is important to multiferroic behaviors in ZnO:Cu. The samples show clear ferroelectric and ferromagnetic domain patterns. These domain structures may be written reversibly via electric and magnetic bias.

  19. Synthesis and characterization of multilayered BaTiO3/NiFe2O4 thin films

    Directory of Open Access Journals (Sweden)

    Branimir Bajac

    2013-03-01

    Full Text Available Presented research was focused on the fabrication of multiferroic thin film structures, composed of ferrielectric barium titanate perovskite phase and magnetostrictive nickel ferrite spinel phase. The applicability of different, solution based, deposition techniques (film growth from solution, dip coating and spin coating for thefabrication of multilayered BaTiO3 /NiFe2O4 thin films was investigated. It was shown that only spin coating produces films of desired nanostructure, thickness and smooth and crackfree surfaces.

  20. Substrate clamping effect onto magnetoelectric coupling in multiferroic BaTiO3-CoFe2O4 core-shell nanofibers via coaxial electrospinning

    Science.gov (United States)

    Fu, Bi; Lu, Ruie; Gao, Kun; Yang, Yaodong; Wang, Yaping

    2015-10-01

    We report large lateral magnetoelectric (ME) coupling coefficients α 31 of 1.2×104 \\text{mV} \\text{cm}-1 \\text{Oe}-1 and 3.5× 104 \\text{mV} \\text{cm}-1 \\text{Oe}-1 in substrate bonded and free-standing multiferroic BaTiO3-CoFe2O4 (BTO-CFO) core-shell nanofibers (NFs) with and without substrate clamping effect, respectively. The BTO-CFO core-shell NFs were synthesised by a sol-gel coaxial electrospinning technique, and their ME coupling was directly observed by demonstrating the evolution of piezoelectric coefficient (d 33), ferroelectric domain, and phase contrast induced by an external magnetic field. These impressed α 31 coefficients originated from the nanoconfinement of the interphase elastic interaction between the ferromagnetic core fiber and the ferroelectric shell interlayer, as well as the strain transformation at the one-dimensional (1D) fiber boundary. This means that the decreasing substrate clamping effect results in an enhanced ME coupling in multiferroic NFs, which is similar to that of thin films. These findings make people understand the substrate clamping effect and enable nanoscale ME device applications.

  1. Electrically Controllable Spontaneous Magnetism in Nanoscale Mixed Phase Multiferroics

    Energy Technology Data Exchange (ETDEWEB)

    He, Q.; Chu, Y. H.; Heron, J. T.; Yang, S. Y.; Wang, C. H.; Kuo, C. Y.; Lin, H. J.; Yu, P.; Liang, C. W.; Zeches, R. J.; Chen, C. T.; Arenholz, E.; Scholl, A.; Ramesh, R.

    2010-08-02

    The emergence of enhanced spontaneous magnetic moments in self-assembled, epitaxial nanostructures of tetragonal (T-phase) and rhombohedral phases (R-phase) of the multiferroic BiFeO{sub 3} system is demonstrated. X-ray magnetic circular dichroism based photoemission electron microscopy (PEEM) was applied to investigate the local nature of this magnetism. We find that the spontaneous magnetization of the R-phase is significantly enhanced above the canted antiferromagnetic moment in the bulk phase, as a consequence of a piezomagnetic coupling to the adjacent T-phase and the epitaxial constraint. Reversible electric field control and manipulation of this magnetic moment at room temperature is shown using a combination of piezoresponse force microscopy and PEEM studies.

  2. Status and Perspectives of Multiferroic Magnetoelectric Composite Materials and Applications

    Directory of Open Access Journals (Sweden)

    Haribabu Palneedi

    2016-03-01

    Full Text Available Multiferroic magnetoelectric (ME composites are attractive materials for various electrically and magnetically cross-coupled devices. Many studies have been conducted on fundamental understanding, fabrication processes, and applications of ME composite material systems in the last four decades which has brought the technology closer to realization in practical devices. In this article, we present a review of ME composite materials and some notable potential applications based upon their properties. A brief summary is presented on the parameters that influence the performance of ME composites, their coupling structures, fabrications processes, characterization techniques, and perspectives on direct (magnetic to electric and converse (electric to magnetic ME devices. Overall, the research on ME composite systems has brought us closer to their deployment.

  3. Enhanced multiferroic properties of Pr doped bismuth ferrite ceramics

    International Nuclear Information System (INIS)

    Pr modified Bi0.9-xLa0.1PrxFeO3 (BLPFO-x, x = 0, 0.1 and 0.2) ceramics were prepared by solid state reaction using oxide reagents and a detailed multiferroic properties is reported. X-ray analysis shows the formation of a bismuth ferrite rhombohedral phase. Pr doping significantly increases the resistivity and leads to a successful observation of electrical polarization hysteresis loops. All the samples have been found to possess a spontaneous magnetic moment at room temperature which increases further at low temperatures. The strong dependence of remnant polarization and dielectric constant on the strength of magnetic field is a direct evidence of magnetoelectric coupling in BLPFO ceramics. (author)

  4. Multifunctional dual-tunable multiferroic Ba0.25Sr0.75TiO3-BiFeO3-Ba0.25Sr0.75TiO3 trilayered structure for tunable microwave applications

    International Nuclear Information System (INIS)

    A multiferroic trilayered structure composed of a BiFeO3 (BFO) layer and two Ba0.25Sr0.75TiO3 (BST) layers is grown on a Pt/TiO2/SiO2/Si substrate by pulsed laser deposition. The trilayered BST/BFO/BST thin film structure exhibits a significant tuning response for the dielectric constant with an electric field and a magnetic field, respectively. Microwave devices based on such multifunctional materials can offer dual, i.e. electric and magnetic, tuning possibility and extra flexibility in designing and shaping the device performances.

  5. Synthesis and induced multiferroicity of perovskite PbTiO3; a review

    Science.gov (United States)

    Bhatti, Humaira Safdar; Hussain, Syed Tajammul; Khan, Feroz Alam; Hussain, Shahzad

    2016-03-01

    Multiferroics are multifunctional materials possessing particularly two significant ferroic orders i.e. ferroelectricity and ferromagnetism. Owing to the technological importance of the multiferroics in a variety of electromagnetic appliances, intensive research has been focused on exploring co-existence and coupling of ferroelectricity and magnetism at room temperature and above. PbTiO3 is a ferroelectric material with the highest spontaneous polarization Ps among all the ferroelectric perovskites. Due to scarcity of multiferroic materials, PbTiO3 is being extensively studied for induction of magnetism. This review deals with the synthesis and study of induced multiferroic behavior in ferroelectric PbTiO3. A variety of synthesis techniques have been discussed for PbTiO3 powders and films which can be modified to tune the electric and magnetic properties in the material. A detailed discussion is presented on the induction and enhancement of multiferroicity in PbTiO3 by substitution of suitable transition-metal dopants and tailoring the size and morphologies. Device applications of the material have been briefly discussed to illustrate its technological importance. Finally the review has been concluded with future perspectives.

  6. Dependence of BiFeO3 thickness on exchange bias in BiFeO3/ Co2FeAl multiferroic structures

    Science.gov (United States)

    Zhang, X.; Zhang, D. L.; Wang, Y. H.; Miao, J.; Xu, X. G.; Jiang, Y.

    2011-01-01

    We have grown BiFeO3 (BFO) thin films with different thickness on Si/SiO2/Ti/Pt(111) substrates by pulsed laser deposition. Half-metallic Co2FeAl (CFA) films with a thickness of 5 nm were then grown on the BFO films by magnetron sputtering. Through the magnetic hysteresis loops of the BFO/CFA heterostructure, we observe a direct correlation between the thickness of the BFO film and exchange bias (EB) field. The EB field exhibits fluctuation behavior with a cyclical BFO thickness of 60 nm, which is close to the spiral modulation wavelength (62 nm) of BFO. It indicates the influence of spiral modulation on the EB in the BFO/CFA multiferroic structure.

  7. Two-Dimensional Multiferroics: Ferroelasticity, Ferroelectricity, Domain Wall, and Potential Mechano-Opto-Electronic Applications

    CERN Document Server

    Wang, Hua

    2016-01-01

    Low-dimensional multiferroic materials hold great promises in miniaturized device applications such as nanoscale transducers, actuators, sensors, photovoltaics, and nonvolatile memories. Here, using first-principles theory we predict that two-dimensional (2D) monolayer Group IV monochalcogenides including GeS, GeSe, SnS, and SnSe are a class of 2D semiconducting multiferroics with strongly coupled giant in-plane spontaneous ferroelectric polarization and spontaneous ferroelastic lattice strain that are thermodynamically stable at room temperature and beyond, and can be effectively modulated by elastic strain engineering. Their optical absorption spectra exhibit strong in-plane anisotropy with visible-spectrum excitonic gaps and sizable exciton binding energies, rendering the unique characteristics of low-dimensional semiconductors. More importantly, the predicted low domain wall energy and small migration barrier together with the coupled multiferroic order and anisotropic electronic structures suggest their ...

  8. Multiferroic hexaferrites: Perspectives for novel functionalities close to room temperature

    Science.gov (United States)

    Krezhov, Kiril

    Advanced materials with a high knowledge-content providing new functionalities, improved performance and greater versatility in application are key drivers of innovation affecting space sciences as well as everyday life. Beside new synthesis techniques there is a need for materials characterisation, design methods and simulation techniques to improve our understanding of materials, in particular the structure-property relationships at different length scales ranging down to nanometer range and smaller. Magnetism and ferroelectricity are essential to many forms of current technology. In this respect, transition-metal oxides exhibit various intriguing phenomena such as relaxor behaviour, high-temperature superconductivity and colossal magnetoresistance. Recent extensive studies unveil another potential of transition-metal oxides as multiferroics - materials that possess two or all three, of the so-called ferroic properties: ferroelectricity, ferromagnetism and ferroelasticity. The attractive feature of these systems is not so much the electrical polarization, which is several orders of magnitude smaller than for typical ferroelectrics, but rather the very large cross-coupling between magnetic and electrical properties. The key to understand these effects lies on one hand in the magneto-elastic interactions coupling spins, atoms and electrons at the microscopic level, and, on the other hand, in the subtle lowering of the magneto-crystalline symmetry from a non-polar to a polar point group. The present paper describes our efforts to identify new candidate materials for multiferroic and magnetoelectric (ME) behaviour, based primarily on considerations of symmetry and the knowledge of the magnetic structure. Recent findings demonstrated that ferroelectricity can be induced by complex internal arrangements of magnetic moments. Once the magnetic structure is known, one can predict which elements of the magnetoelectric tensors are allowed, and, as a consequence, which

  9. An introduction to the use of representation analysis for studying magnetoelectrics and multiferroics

    Directory of Open Access Journals (Sweden)

    Chapon L.C.

    2012-03-01

    Full Text Available This lecture is an introduction to the theory of representations applied to the study of magnetoelectric and multiferroic materials. It is intended for students or newcomers in the field and explains the key concepts required to understand phenomenologically the coupling between magnetic phase transitions in crystals and dielectric properties. Symmetry properties of some prototypal magnetoelectrics and multiferroics are analysed, including the treatment of incommensurate spin-driven ferroelectrics. It is deliberately written with a minimal use of mathematical formulation or a strict group theoretical approach.

  10. Effect of periodicity on order parameters of multiferroic superlattices

    Science.gov (United States)

    Kumari, Shalini; Ortega, Nora; Kumar, Ashok; Katiyar, Ram

    2015-03-01

    Superlattice (SL) structures with alternating perovskite oxide layers have attracted enormous attention due to involved fascinating physics and technology. The half-metallic oxide La0.67Sr0.33MnO3(LSMO) and multiferroic Pb(Zr0.53Ti0.47)0.60 (Fe0.5Ta0.5)0.40 O3(PZTFT) materials have been chosen to fabricate SLs by pulsed laser deposition technique on cubic LSAT substrates with LSMO or LaNiO3 as bottom electrodes. X-ray diffraction studies revealed superlattice structure with satellite peaks modulated around main peaks. Atomic force microscopy studies disclosed a systematic decrease in grain size with decrease of modulation periodicity (Λ) in SLs. Piezo force microscopy studies of SL films confirmed ferroelectricity at a nanoscale level. XPS studies of SLs with Λ = 5 nm confirmed the existence of all elements in the films. A relatively small reduction in saturation magnetization from 28 to 20 emu/cm3at H =5 kOe, remanant polarization from 21 to 10 μC/cm2 and increase in dielectric constant from 530 to 743 were observed with decrease of Λ.The observed features will be explained in context of finite size, interfaces, stress, lattice distortion, and grain sizes effects. NSF Grant EPS-01002410

  11. Unusual Mott transition in multiferroic PbCrO3.

    Science.gov (United States)

    Wang, Shanmin; Zhu, Jinlong; Zhang, Yi; Yu, Xiaohui; Zhang, Jianzhong; Wang, Wendan; Bai, Ligang; Qian, Jiang; Yin, Liang; Sullivan, Neil S; Jin, Changqing; He, Duanwei; Xu, Jian; Zhao, Yusheng

    2015-12-15

    The Mott insulator in correlated electron systems arises from classical Coulomb repulsion between carriers to provide a powerful force for electron localization. Turning such an insulator into a metal, the so-called Mott transition, is commonly achieved by "bandwidth" control or "band filling." However, both mechanisms deviate from the original concept of Mott, which attributes such a transition to the screening of Coulomb potential and associated lattice contraction. Here, we report a pressure-induced isostructural Mott transition in cubic perovskite PbCrO3. At the transition pressure of ∼3 GPa, PbCrO3 exhibits significant collapse in both lattice volume and Coulomb potential. Concurrent with the collapse, it transforms from a hybrid multiferroic insulator to a metal. For the first time to our knowledge, these findings validate the scenario conceived by Mott. Close to the Mott criticality at ∼300 K, fluctuations of the lattice and charge give rise to elastic anomalies and Laudau critical behaviors resembling the classic liquid-gas transition. The anomalously large lattice volume and Coulomb potential in the low-pressure insulating phase are largely associated with the ferroelectric distortion, which is substantially suppressed at high pressures, leading to the first-order phase transition without symmetry breaking. PMID:26604314

  12. A simple model for the magnetoelectric interaction in multiferroics

    Energy Technology Data Exchange (ETDEWEB)

    Filho, Cesar J Calderon; Barberis, Gaston E, E-mail: barberis@ifi.unicamp.br [Instituto de fisica ' Gleb Wataghin' , UNICAMP, 13083-970, Campinas, Sao Paulo (Brazil)

    2011-01-01

    The (anti)ferromagnetic and ferroelectric transitions in some multiferroic compounds seem to be strongly correlated. Even for systems that do not show spontaneous ferroelectricity such as the LiMPO{sub 4} (M = Mn, Fe, Co, Ni) compounds, the coupling between magnetic and electric degrees of freedom is evident experimentally. Here, we present a simple numerical calculation to simulate this coupling that leads to the two transitions. We assume a magnetic sublattice consisting of classical magnetic moments coupled to a separated nonmagnetic sublattice consisting of classical electric dipoles. The coupling between them is realized through a phenomenological spin-lattice Hamiltonian, and the solution is obtained using the Monte Carlo technique. In the simplest version, the magnetic system is 2D Ising (anti)ferromagnetic lattice, with nearest neighbors interactions only, and the electric moments are permanent moments, coupled electrically. Within this approximation, the second order magnetic transition induces ferroelectricity in the electric dipoles. We show that these calculations can be extended to other magnetic systems, (x-y model and 3D Heisenberg) and to systems where the electric moments are created by strains, generated via spin-lattice coupling, so the model can be applied to model realistic systems such as the olivines mentioned above.

  13. Anharmonic lattice interactions in improper ferroelectrics for multiferroic design

    International Nuclear Information System (INIS)

    The design and discovery of new multiferroics, or materials that display both ferroelectricity and long-range magnetic order, is of fundamental importance for new electronic technologies based on low-power consumption. Far too often, however, the mechanisms causing these properties to arise are incompatible or occur at ordering temperatures below room temperature. One design strategy which has gained considerable interest is to begin with a magnetic material, and find novel ways to induce a spontaneous electric polarization within the structure. To this end, anharmonic interactions coupling multiple lattice modes have been used to lift inversion symmetry in magnetic dielectrics. Here we provide an overview of the microscopic mechanisms by which various types of cooperative atomic displacements result in ferroelectricity through anharmonic multi-mode coupling, as well as the types of materials most conducive to these lattice instabilities. The review includes a description of the origins of the displacive modes, a classification of possible non-polar lattice modes, as well as how their coupling can produce spontaneous polarizations. We then survey the recent improper ferroelectric literature, and describe how the materials discussed fall within a proposed classification scheme, offering new directions for the theoretical design of magnetic ferroelectrics. Finally, we offer prospects for the future discovery of new magnetic improper ferroelectrics, as well as detail remaining challenges and open questions facing this exciting new field. (topical review)

  14. Thermal generation of spin current in a multiferroic helimagnet

    Directory of Open Access Journals (Sweden)

    R. Takagi

    2016-03-01

    Full Text Available We report the experimental observation of longitudinal spin Seebeck effect in a multiferroic helimagnet Ba0.5Sr1.5Zn2Fe12O22. Temperature gradient applied normal to Ba0.5Sr1.5Zn2Fe12O22/Pt interface generates inverse spin Hall voltage of spin current origin in Pt, whose magnitude was found to be proportional to bulk magnetization of Ba0.5Sr1.5Zn2Fe12O22 even through the successive magnetic transitions among various helimagnetic and ferrimagnetic phases. This finding demonstrates that the helimagnetic spin wave can be an effective carrier of spin current. By controlling the population ratio of spin-helicity domains characterized by clockwise/counter-clockwise manner of spin rotation with use of poling electric field in the ferroelectric helimagnetic phase, we found that spin-helicity domain distribution does not affect the magnitude of spin current injected into Pt. The results suggest that the spin-wave spin current is rather robust against the spin-helicity domain wall, unlike the case with the conventional ferromagnetic domain wall.

  15. Thermal generation of spin current in a multiferroic helimagnet

    Science.gov (United States)

    Takagi, R.; Tokunaga, Y.; Ideue, T.; Taguchi, Y.; Tokura, Y.; Seki, S.

    2016-03-01

    We report the experimental observation of longitudinal spin Seebeck effect in a multiferroic helimagnet Ba0.5Sr1.5Zn2Fe12O22. Temperature gradient applied normal to Ba0.5Sr1.5Zn2Fe12O22/Pt interface generates inverse spin Hall voltage of spin current origin in Pt, whose magnitude was found to be proportional to bulk magnetization of Ba0.5Sr1.5Zn2Fe12O22 even through the successive magnetic transitions among various helimagnetic and ferrimagnetic phases. This finding demonstrates that the helimagnetic spin wave can be an effective carrier of spin current. By controlling the population ratio of spin-helicity domains characterized by clockwise/counter-clockwise manner of spin rotation with use of poling electric field in the ferroelectric helimagnetic phase, we found that spin-helicity domain distribution does not affect the magnitude of spin current injected into Pt. The results suggest that the spin-wave spin current is rather robust against the spin-helicity domain wall, unlike the case with the conventional ferromagnetic domain wall.

  16. Finite-temperature properties of multiferroic BiFeO3

    DEFF Research Database (Denmark)

    Kornev, Igor; Lisenkov, S; Haumont, R; Dkhil, B; Bellaiche, L

    2007-01-01

    An effective Hamiltonian scheme is developed to study finite-temperature properties of multiferroic BiFeO3. This approach reproduces very well (i) the symmetry of the ground state, (ii) the Néel and Curie temperatures, and (iii) the intrinsic magnetoelectric coefficients (that are very weak). Thi...

  17. Magnetic dispersion and anisotropy in multiferroic BiFeO3

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Masaaki [ORNL; Fishman, Randy Scott [ORNL; Hong, Tao [ORNL; Lee, C. H. [AIST, Japan; Ushiyama, T. [AIST, Japan; Yanagisawa, Y. [AIST, Japan; Tomioka, Y. [AIST, Japan; Ito, T. [AIST, Japan

    2012-01-01

    We have determined the full magnetic dispersion relations of multiferroic BiFeO3. In particular, two excitation gaps originating from magnetic anisotropies have been clearly observed. The direct observation of the gaps enables us to accurately determine the Dzyaloshinskii-Moriya (DM) interaction and the single ion anisotropy. The DM interaction supports a sizable magneto-electric coupling in this compound.

  18. Evidence for multiferroic characteristics in NdCrTiO5

    International Nuclear Information System (INIS)

    We report NdCrTiO5 to be an unusual multiferroic material with large magnetic field dependent electric polarization. While magneto-electric coupling in this two magnetic sub-lattice oxide is well established, the purpose of this study is to look for spontaneous symmetry breaking at the magnetic transition. The conclusions are based on extensive magnetization, dielectric and polarization measurements around its antiferromagnetic ordering temperature of 18 K. Room temperature X-ray diffraction pattern of NdCrTiO5 reveals that the sample is single phase with an orthorhombic crystal structure that allows linear magneto-electric coupling. DC magnetization measurement shows magnetization downturn at 11 K together with a small kink corresponding to the Cr+3 sub-lattice ordering at ∼18 K. An anomaly in dielectric constant is observed around the magnetic ordering temperature that increases substantially with increasing magnetic field. Through detailed pyroelectric current measurements at zero magnetic field, particularly as a function of thermal cycling, we establish that NdCrTiO5 is a genuine multiferroic material that is possibly driven by collinear magneto-striction. - Highlights: • We provide evidence for multiferroicity in NdCrTiO5. • Large magnetic field dependent electric polarization is confirmed. • Sign reversal of pyroelectric current upon thermal cycling proves genuine ferroelectricity. • A model based on collinear magneto-striction is proposed. • A new class of multiferroic materials with large ME coupling is established

  19. A multiferroic material to search for the permanent electric dipole moment of the electron

    Czech Academy of Sciences Publication Activity Database

    Rushchanskii, K.Z.; Kamba, Stanislav; Goian, Veronica; Vaněk, Přemysl; Savinov, Maxim; Prokleška, J.; Nuzhnyy, Dmitry; Knížek, Karel; Laufek, F.; Eckel, S.; Lamoreaux, S.K.; Sushkov, A.; Ležaič, M.; Spaldin, N.A.

    2010-01-01

    Roč. 9, č. 8 (2010), s. 649-654. ISSN 1476-1122 R&D Projects: GA ČR(CZ) GA202/09/0682 Institutional research plan: CEZ:AV0Z10100520 Keywords : multiferroics * electric dipole moment of the electron * dielectric and magnetic properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 29.897, year: 2010

  20. Lieb-Mattis ferrimagnetic superstructure and superparamagnetism in Fe-based double perovskite multiferroics

    Czech Academy of Sciences Publication Activity Database

    Kuzian, R. O.; Laguta, Valentyn; Richter, J.

    2014-01-01

    Roč. 90, č. 13 (2014), "134415-1"-"134415-13". ISSN 1098-0121 R&D Projects: GA ČR GA13-11473S Institutional support: RVO:68378271 Keywords : multiferroics * superantiferromagnetism * DFT calculations Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  1. Role of rare-earth ionic radii on the spin-phonon coupling in multiferroic ordered double perovskites

    Czech Academy of Sciences Publication Activity Database

    Macedo Filho, R.B.; Barbosa, D.A.B.; Reichlová, Helena; Martí, Xavier; de Menezes, A.S.; Ayala, A.P.; Paschoal, C.W.A.

    2015-01-01

    Roč. 7, č. 2 (2015), 075201. ISSN 2053-1591 Institutional support: RVO:68378271 Keywords : double perovskites * spin-phonon coupling * multiferroics Subject RIV: BM - Solid Matter Physics ; Magnetism

  2. Atomic Structure of Highly Strained BiFeO3 Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Rossell, M.D. [Lawrence Berkeley National Laboratory (LBNL); Erni, R. [Lawrence Berkeley National Laboratory (LBNL); Prange, Micah P [ORNL; Idrobo Tapia, Juan C [ORNL; Luo, Weidong [ORNL; Zeches, R J [University of California, Berkeley; Pantelides, Sokrates T [ORNL; Ramesh, R [Lawrence Berkeley National Laboratory (LBNL)

    2012-01-01

    We determine the atomic structure of the pseudotetragonal T phase and the pseudorhombohedral R phase in highly strained multiferroic BiFeO3 thin films by using a combination of atomic-resolution scanning transmission electron microscopy and electron energy-loss spectroscopy. The coordination of the Fe atoms and their displacement relative to the O and Bi positions are assessed by direct imaging. These observations allow us to interpret the electronic structure data derived from electron energy-loss spectroscopy and provide evidence for the giant spontaneous polarization in strained BiFeO3 thin films.

  3. Optimization of excess Bi doping to enhance ferroic orders of spin casted BiFeO3 thin film

    International Nuclear Information System (INIS)

    Multiferroic Bismuth Ferrite (BiFeO3) thin films with varying excess bismuth (Bi) concentration were grown by chemical solution deposition technique. Room temperature multiferroic properties (ferromagnetism, ferroelectricity, and piezoelectricity) of the deposited BiFeO3 thin films have been studied. High resolution X-ray diffraction and Raman spectroscopy studies reveal that the dominant phases formed in the prepared samples change continuously from a mixture of BiFeO3 and Fe2O3 to pure BiFeO3 phase and, subsequently, to a mixture of BiFeO3 and Bi2O3 with increase in the concentration of excess Bi from 0% to 15%. BiFeO3 thin films having low content (0% and 2%) of excess Bi showed the traces of ferromagnetic phase (γ-Fe2O3). Deterioration in ferroic properties of BiFeO3 thin films is also observed when prepared with higher content (15%) of excess Bi. Single-phased BiFeO3 thin film prepared with 5% excess Bi concentration exhibited the soft ferromagnetic hysteresis loops and ferroelectric characteristics with remnant polarization 4.2 μC/cm2 and saturation magnetization 11.66 emu/g. The switching of fine spontaneous domains with applied dc bias has been observed using piezoresponse force microscopy in BiFeO3 thin films having 5% excess Bi. The results are important to identify optimum excess Bi concentration needed for the formation of single phase BiFeO3 thin films exhibiting the improved multiferroic properties.

  4. Magnetic Structure of Multiferroic BiFeO3 Film with Engineered Ferroelectric Domains

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, P.P [Michigan State University, East Lansing; Baek, S H [University of Wisconsin; Zarestky, Jerel L. [Ames Laboratory; Tian, Wei [Ames Laboratory and Iowa State University; Eom, C-B [HSX Laboratory, University of Wisconsin-Madison

    2010-10-01

    We report on neutron scattering and piezoresponse force microscopy studies of multiferroic BiFeO{sub 3} films epitaxially grown on vicinal SrTiO{sub 3} substrates. We find that these BiFeO{sub 3} films exhibit a G-type antiferromagnetic structure modulated with cycloidal spiral magnetic ordering with the features of magnetic domains depending upon the ferroelectric domain states: a single antiferromagnetic domain for the films with a ferroelectric monodomain while two- or multiantiferromagnetic domains existing in the films displaying two- or four-ferroelectric variants, respectively. These results imply the correlation between ferroelectric and magnetic order parameters in the BiFeO{sub 3} films and the expected strong magnetoelectric coupling makes these multiferroic films promising candidates for device applications with the capability to tune the magnetism using an electric field.

  5. Multiferroicity in ZnO nanodumbbell/BiFeO3 nanoparticle heterostructures

    Science.gov (United States)

    Mahesh, Dabbugalla; Mandal, Swapan K.

    2016-04-01

    We report here on the multiferroic properties of ZnO-BiFeO3 (BiFeO3 referred hereinafter as BFO) nanocomposite structures obtained by using a facile solution-based synthesis route. ZnO is found to grow in the form of well-crystallized and self-assembled dumbbell-like structures. BFO nanoparticles (NPs) are deposited onto ZnO nanodumbbells (NDs) to obtain ZnO-BFO heterostructures. The nanocomposites show prominent ferroelectric polarization hysteresis loop along with enhanced magnetization in comparison to pure BFO NPs. The ordered alignment of spins along with the suppression of Fe-O-Fe antiferromagnetic super-exchange interactions at the ZnO/BFO interface plausibly gives rise to observed multiferroic properties.

  6. Gigantic directional asymmetry of luminescence in multiferroic CuB 2O 4

    Science.gov (United States)

    Toyoda, S.; Abe, N.; Arima, T.

    2016-05-01

    In multiferroic materials, luminescence intensities can be direction dependent, i.e., different between the opposite propagating directions of emitted light. However, the effect has not been thought to be used for technological applications, since only small directional asymmetry has been reported so far. Here we show that the effect is robust in multiferroic CuB2O4 . The luminescence intensity changes by about 70 % between the opposite directions of the emission, which is about 100 times larger than the previously reported values. We demonstrate that such a gigantic directional asymmetry of luminescence can be applied to the imaging of canted antiferromagnetic domains. The observation of the effect and its application to magnetic domain imaging are important for a deeper understanding of light-matter interactions as well as technological applications such as optical reading techniques for magnetic memory devices.

  7. Electric Field Control of the Resistance of Multiferroic Tunnel Junctions with Magnetoelectric Antiferromagnetic Barriers

    Science.gov (United States)

    Merodio, P.; Kalitsov, A.; Chshiev, M.; Velev, J.

    2016-06-01

    Based on model calculations, we predict a magnetoelectric tunneling electroresistance effect in multiferroic tunnel junctions consisting of ferromagnetic electrodes and magnetoelectric antiferromagnetic barriers. Switching of the antiferromagnetic order parameter in the barrier in applied electric field by means of the magnetoelectric coupling leads to a substantial change of the resistance of the junction. The effect is explained in terms of the switching of the orientations of local magnetizations at the barrier interfaces affecting the spin-dependent interface transmission probabilities. Magnetoelectric multiferroic materials with finite ferroelectric polarization exhibit an enhanced resistive change due to polarization-induced spin-dependent screening. These results suggest that devices with active barriers based on single-phase magnetoelectric antiferromagnets represent an alternative nonvolatile memory concept.

  8. Competition of magneto-dipole, anisotropy and exchange interactions in composite multiferroics.

    Science.gov (United States)

    Belemuk, A M; Udalov, O G; Chtchelkatchev, N M; Beloborodov, I S

    2016-03-31

    We study the competition of magneto-dipole, anisotropy and exchange interactions in composite three-dimensional multiferroics. Using Monte Carlo simulations we show that magneto-dipole interaction does not suppress the ferromagnetic state caused by the interaction of the ferroelectric matrix and magnetic subsystem. However, the presence of the magneto-dipole interaction influences the order-disorder transition: depending on the strength of magneto-dipole interaction the transition from the ferromagnetic to the superparamagnetic state is accompanied either by the creation of vortices or domains of opposite magnetization. An unusual temperature hysteresis loop occurs in composite multiferroics due to non-monotonic behavior of exchange interaction versus temperature. The origin of this hysteresis is related to the presence of stable magnetic domains which are robust against thermal fluctuations. PMID:26909471

  9. Effects of transition metal doping on multiferroic ordering in nickel vanadate and iron orthovanadate

    Science.gov (United States)

    Kumarasiri, Akila

    We have studied the effects of doping both non-magnetic and magnetic ions on the phase transitions and multiferroic ordering in two multiferroic oxides; Ni3V2O8 and FeVO4. Magnetic, dielectric, specific heat, polarization and AC susceptibility measurements were used to track changes in phase transition temperatures. We found that the two higher temperature magnetic transitions in Ni3V2O 8; TH = 9.1 K and TL = 6.3 K are suppressed to lower temperatures with all transition metal dopants. For Zn doping, the rates of the suppression of both TH and TL with dopant fraction are consistent with simple site dilution for two-dimensional spin systems, with the suppression of TH consistent with Ising spins and the suppression of TL consistent with Heisenberg spins. However, samples remain multiferroic at least up to 15% Zn doping. Conversely, spin-1/2 Cu doping strongly suppresses both transitions, for which the multiferroic magnetic structure is completely suppressed at only 10% Cu doping. However, below 10% Cu doping, the samples show enhanced ferroelectric polarization, and a sizable net magnetization also develops. With spin-3/2 Co doping, suppression is very small, with the multiferroic transition persisting even at 30% doping and the material showing Ni 3V2O8 magnetic characteristics up to 80% doping. On the Co rich side of the composition, we find that the magnetic ordering temperatures for Co3V2O8 are suppressed rapidly with Ni doping. With higher spin dopants (e.g. spin-2 Fe and spin-5/2 Mn), suppression remains fairly low. We also present phase diagrams for (Ni 1-xMx)3V2O8 (M = Zn, Cu, Co, Fe and Mn). These studies suggest that the spin structures in Ni3V 2O8 responsible for the development of ferroelectric order are relatively robust against perturbations produced by both magnetic and non-magnetic dopants, with the most significant disruption of the magnetic structure developing for Cu doping. In the case of FeVO4, we find that the magnetoelectric coupling in FeVO4

  10. Antiferromagnetic resonance in multiferroic YMnO3 and LuMnO3

    International Nuclear Information System (INIS)

    Multiferroic rare-earth manganites have attracted much attention because of the coexistence of ferroelectric and magnetic order. Combining conventional far-infrared Fourier-transform and THz-range free electron laser electron spin resonance (ESR) techniques, magnetic excitations in the hexagonal multiferroic materials YMnO3 and LuMnO3 have been studied. In the antiferromagnetically (AFM) ordered phase the gap in the excitation spectrum (∝42 and ∝48 cm-1 for YMnO3 and LuMnO3, respectively) was observed directly. Similar slope of the frequency-field dependences of the AFM resonance modes, ∝ 0.5 cm-1/T, was found for both compounds. A fine structure of the AFM resonance absorption has been revealed by means of high-resolution ESR techniques, which can be explained taking into account a finite interaction between the neighboring Mn3+ layers.

  11. Competition of magneto-dipole, anisotropy and exchange interactions in composite multiferroics

    International Nuclear Information System (INIS)

    We study the competition of magneto-dipole, anisotropy and exchange interactions in composite three-dimensional multiferroics. Using Monte Carlo simulations we show that magneto-dipole interaction does not suppress the ferromagnetic state caused by the interaction of the ferroelectric matrix and magnetic subsystem. However, the presence of the magneto-dipole interaction influences the order–disorder transition: depending on the strength of magneto-dipole interaction the transition from the ferromagnetic to the superparamagnetic state is accompanied either by the creation of vortices or domains of opposite magnetization. An unusual temperature hysteresis loop occurs in composite multiferroics due to non-monotonic behavior of exchange interaction versus temperature. The origin of this hysteresis is related to the presence of stable magnetic domains which are robust against thermal fluctuations. (paper)

  12. Temperature dependences of the electric polarization and wave number of incommensurate structures in multiferroics

    Science.gov (United States)

    Pikin, S. A.

    2016-05-01

    It is shown that the electric polarization and wave number of incommensurate modulations, proportional to each other, increase according to the Landau law in spin multiferroic cycloids near the Néel temperature. In this case, the constant magnetization component (including the one for a conical spiral) is oriented perpendicular to the spin incommensurability wave vector. A similar temperature behavior should manifest itself for spin helicoids, the axes of which are oriented parallel to the polarization vector but their spin rotation planes are oriented perpendicular to the antiferromagnetic order plane. When the directions of axes of the magnetization helicoid and polarization vector coincide, the latter is quadratic with respect to magnetization and linearly depends on temperature, whereas the incommensurate-modulation wave number barely depends on temperature. Structural distortions of unit cells for multiferroics of different types determine their axial behavior.

  13. Perturbed angular correlations investigations on YMnO3 multiferroic manganite

    International Nuclear Information System (INIS)

    The Perturbed Angular Correlation (PAC) technique was applied to study the yttrium local environment in YMnO3 multiferroic manganite. The electric field gradients (EFG) at the Y site have been measured as function of temperature, covering both ferroelectric and magnetic transitions. The results were compared with point charge model (PCM) calculations. The experimental results show two different EFG distributions for all temperatures. Only one can be directly attributed to the yttrium crystalline site in the hexagonal structure.

  14. Quantitative off-axis Electron Holography and (multi-)ferroic interfaces

    OpenAIRE

    Lubk, Axel

    2010-01-01

    A particularly interesting class of modern materials is ferroic ceramics. Their characteristic order parameter is a result of quantum chemistry taking place on a sub-Å length scale and long-range couplings, e.g. mediated by electrostatic or stress fields. Furthermore, the particular subclass of multiferroics possesses more than one order parameter and exhibits an intriguing coupling between them, which is interesting both from the fundamental physics point of view as well as from a technologi...

  15. Control of multiferroic domains by external electric fields in TbMnO3

    OpenAIRE

    Stein, Jonas; Baum, Max; Holbein, Simon; Hutanu, Vladimir; Komarek, Alexander C.; Braden, Markus

    2015-01-01

    The control of multiferroic domains through external electric fields has been studied by dielectric measurements and by polarized neutron diffraction on single-crystalline TbMnO$_3$. Full hysteresis cycles were recorded by varying an external field of the order of several kV/mm and by recording the chiral magnetic scattering as well as the charge in a sample capacitor. Both methods yield comparable coercive fields that increase upon cooling.

  16. Control of multiferroic domains by external electric fields in TbMnO3

    Science.gov (United States)

    Stein, J.; Baum, M.; Holbein, S.; Cronert, T.; Hutanu, V.; Komarek, A. C.; Braden, M.

    2015-11-01

    The control of multiferroic domains through external electric fields has been studied by dielectric measurements and by polarized neutron diffraction on single-crystalline TbMnO3. Full hysteresis cycles were recorded by varying an external field of the order of several kV mm-1 and by recording the chiral magnetic scattering as well as the charge in a sample capacitor. Both methods yield comparable coercive fields that increase upon cooling.

  17. Control of multiferroic domains by external electric fields in TbMnO₃.

    Science.gov (United States)

    Stein, J; Baum, M; Holbein, S; Cronert, T; Hutanu, V; Komarek, A C; Braden, M

    2015-11-11

    The control of multiferroic domains through external electric fields has been studied by dielectric measurements and by polarized neutron diffraction on single-crystalline TbMnO3. Full hysteresis cycles were recorded by varying an external field of the order of several kV mm(-1) and by recording the chiral magnetic scattering as well as the charge in a sample capacitor. Both methods yield comparable coercive fields that increase upon cooling. PMID:26452106

  18. Giant Magnetoelastic Effects in BaTiO3-based Extrinsic Multiferroic Hybrids

    OpenAIRE

    Gepraegs, Stephan; Opel, Matthias; Goennenwein, Sebastian T. B.; Gross, Rudolf

    2012-01-01

    Extrinsic multiferroic hybrid structures consisting of ferromagnetic and ferroelectric layers elastically coupled to each other are promising due to their robust magnetoelectric effects even at room temperature. For a quantitative analysis of these magnetoelectric effects, a detailed knowledge of the piezoelectric and magnetoelastic behavior of both constituents as well as their mutual elastic coupling is mandatory. We here report on a theoretical and experimental study of the magnetic behavi...

  19. Manipulating ferroelectric domains of multiferroic DyMnO3 by soft X-rays

    International Nuclear Information System (INIS)

    In multiferroic DyMnO3, ferroelectricity is induced by cycloidal magnetic structures of a chirality coupled to the direction of the electric polarization. XRMS at the Dy-M5 resonance allows to distinguish surface regions of different chirality of the Dy-4f magnetic cycloid and, hence, can be used to image ferroelectric domains. Furthermore, the X-ray beam itself can be utilized to manipulate the distribution of domains at the crystal surface.

  20. A new (Ba, Ca) (Ti, Zr)O3 based multiferroic composite with large magnetoelectric effect.

    Science.gov (United States)

    Naveed-Ul-Haq, M; Shvartsman, Vladimir V; Salamon, Soma; Wende, Heiko; Trivedi, Harsh; Mumtaz, Arif; Lupascu, Doru C

    2016-01-01

    The lead-free ferroelectric 0.5Ba(Zr0.2Ti0.8)O3 - 0.5(Ba0.7Ca0.3)TiO3 (BCZT) is a promising component for multifunctional multiferroics due to its excellent room temperature piezoelectric properties. Having a composition close to the polymorphic phase boundary between the orthorhombic and tetragonal phases, it deserves a case study for analysis of its potential for modern electronics applications. To obtain magnetoelectric coupling, the piezoelectric phase needs to be combined with a suitable magnetostrictive phase. In the current article, we report on the synthesis, dielectric, magnetic, and magnetoelectric characterization of a new magnetoelectric multiferroic composite consisting of BCZT as a piezoelectric phase and CoFe2O4 (CFO) as the magnetostrictive phase. We found that this material is multiferroic at room temperature and manifests a magnetoelectric effect larger than that of BaTiO3 -CoFe2O4 bulk composites with similar content of the ferrite phase. PMID:27555563

  1. Characterization of energy conversion of multiferroic PFN and PFN:Mn

    Directory of Open Access Journals (Sweden)

    Lucjan Kozielski

    2013-12-01

    Full Text Available Characterization of energy conversion of multiferroic materials is concerned with multifunctional properties of materials, a topic that is fascinating from the scientific point of view and important for the modern technology. The complex characterization of multiferroic structures suffers at present from lack of a systematic experimental approach and deficiency of multifunctional magnetoelectric properties testing capabilities. Compactness and high frequency energy conversion capacity are the main reasons of invention and improvement of sophisticated materials which are prepared for high-speed computer memories and broadband transducer devices. As a consequence, one can easily notice an intense search for new materials for generation, transformation and amplification of magnetic and electric energies. In this scenario, the combination of excellent piezoelectric and magnetic properties makes lead iron niobate Pb(Fe1/2Nb1/2O3 (PFN an attractive host material for application in integrated magnetoelectric energy conversion applications. PFN multiferroic materials are attractive for commercial electroceramics due to high value of dielectric permittivity and magnetoelectric coefficients as well as relatively easy synthesis process. However, synthesis of PFN ceramics is mostly connected with formation of the secondary unwanted pyrochlore phase associated with dramatic decrease of ferroelectric properties. The authors have successfully reduced this negative phenomenon by Mn doping and finally present high piezoelectric and magnetoelectric energy conversion efficiency in fabricated PMFN ceramics.

  2. Structure-property relationships of multiferroic materials: A nano perspective

    Science.gov (United States)

    Bai, Feiming

    The integration of sensors, actuators, and control systems is an ongoing process in a wide range of applications covering automotive, medical, military, and consumer electronic markets. Four major families of ceramic and metallic actuators are under development: piezoelectrics, electrostrictors, magnetostrictors, and shape-memory alloys. All of these materials undergo at least two phase transformations with coupled thermodynamic order parameters. These transformations lead to complex domain wall behaviors, which are driven by electric fields (ferroelectrics), magnetic fields (ferromagnetics), or mechanical stress (ferroelastics) as they transform from nonferroic to ferroic states, contributing to the sensing and actuating capabilities. This research focuses on two multiferroic crystals, Pb(Mg1/3Nb 2/3)O3-PbTiO3 and Fe-Ga, which are characterized by the co-existence and coupling of ferroelectric polarization and ferroelastic strain, or ferro-magnetization and ferroelastic strain. These materials break the conventional boundary between piezoelectric and electrostrictors, or magnetostrictors and shape-memory alloys. Upon applying field or in a poled condition, they yield not only a large strain but also a large strain over field ratio, which is desired and much benefits for advanced actuator and sensor applications. In this thesis, particular attention has been given to understand the structure-property relationships of these two types of materials from atomic to the nano/macro scale. X-ray and neutron diffraction were used to obtain the lattice structure and phase transformation characteristics. Piezoresponse and magnetic force microscopy were performed to establish the dependence of domain configurations on composition, thermal history and applied fields. It has been found that polar nano regions (PNRs) make significant contributions to the enhanced electromechanical properties of PMN-x%PT crystals via assisting intermediate phase transformation. With increasing PT

  3. Multiferroic nature of intrinsic point defects in BiFeO3: A hybrid Hartree-Fock density functional study

    Science.gov (United States)

    Shimada, Takahiro; Matsui, Takahiro; Xu, Tao; Arisue, Kou; Zhang, Yajun; Wang, Jie; Kitamura, Takayuki

    2016-05-01

    To achieve a fundamental understanding of the multiferroic behavior and electronic properties of intrinsic vacancies in BiFe O3 , here we performed first-principles calculations based on hybrid Hartree-Fock density functional theories, which can accurately describe defect electronic structures. Oxygen vacancies, which behave as deep donors with high concentrations under oxygen-poor conditions, reduce the magnetic moments at neighboring Fe ions in the neutral state, while charged oxygen vacancies induce additional ferroelectric polarizations. Cation vacancies, on the other hand, are likely to form under oxygen-rich conditions and result in multiferroic properties distinct from those induced by oxygen vacancies. Bi vacancies act as triple-shallow acceptors and strongly suppress spontaneous polarization regardless of charge states, while Fe vacancies locally interfere with both electric and spin polarization and are thus regarded as multiferroic singular points in BiFe O3 . A rich variety of the multiferroic behavior of vacancies can be systematically understood from the localized/delocalized features of defect states, and the different formation conditions for vacancies provide a strategy to tailor the multiferroic properties of BiFe O3 through control of the concentration and charge states of vacancies.

  4. Ab initio study of magnetoelectric coupling in La0.66Sr0.33MnO3 / PbZr0.2Ti0.8O3 multiferroic heterostructures.

    Science.gov (United States)

    Hammouri, Mahmoud; Fohtung, Edwin; Vasiliev, Igor

    2016-10-01

    Multiferroic heterostructures composed of thin layers of ferromagnetic and ferroelectric perovskites have attracted considerable attention in recent years. We apply ab initio computational methods based on density functional theory to study the magnetoelectric coupling at the (0 0 1) interface between [Formula: see text] (LSMO) and [Formula: see text] (PZT). Our study demonstrates that the ferroelectric polarization of PZT has a strong influence on the distribution of magnetization in LSMO. The presence of polarized PZT changes the balance between the ferromagnetic and antiferromagnetic states of LSMO. The observed interfacial magnetoelectric effect can be explained by the variation of the charge density across the LSMO/PZT interface and by the change of the magnetic order in the LSMO layer adjacent to PZT. PMID:27494690

  5. Brillouin light scattering study of transverse mode coupling in confined yttrium iron garnet/barium strontium titanate multiferroic

    International Nuclear Information System (INIS)

    Using the space-resolved Brillouin light scattering spectroscopy we study the transformation of dynamic magnetization patterns in a bilayer multiferroic structure. We show that in the comparison with a single yttrium iron garnet (YIG) film magnetization distribution is transformed in the bilayer structure due to the coupling of waves propagating both in an YIG film (magnetic layer) and in a barium strontium titanate slab (ferroelectric layer). We present a simple electrodynamic model using the numerical finite element method to show the transformation of eigenmode spectrum of confined multiferroic. In particular, we demonstrate that the control over the dynamic magnetization and the transformation of spatial profiles of transverse modes in magnetic film of the bilayer structure can be performed by the tuning of the wavevectors of transverse modes. The studied confined multiferroic stripe can be utilized for fabrication of integrated dual tunable functional devices for magnonic applications

  6. Brillouin light scattering study of transverse mode coupling in confined yttrium iron garnet/barium strontium titanate multiferroic

    Energy Technology Data Exchange (ETDEWEB)

    Sadovnikov, A. V., E-mail: sadovnikovav@gmail.com; Nikitov, S. A. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation); Kotel' nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow 125009 (Russian Federation); Beginin, E. N.; Bublikov, K. V.; Grishin, S. V.; Sheshukova, S. E.; Sharaevskii, Yu. P. [Laboratory “Metamaterials,” Saratov State University, Saratov 410012 (Russian Federation)

    2015-11-28

    Using the space-resolved Brillouin light scattering spectroscopy we study the transformation of dynamic magnetization patterns in a bilayer multiferroic structure. We show that in the comparison with a single yttrium iron garnet (YIG) film magnetization distribution is transformed in the bilayer structure due to the coupling of waves propagating both in an YIG film (magnetic layer) and in a barium strontium titanate slab (ferroelectric layer). We present a simple electrodynamic model using the numerical finite element method to show the transformation of eigenmode spectrum of confined multiferroic. In particular, we demonstrate that the control over the dynamic magnetization and the transformation of spatial profiles of transverse modes in magnetic film of the bilayer structure can be performed by the tuning of the wavevectors of transverse modes. The studied confined multiferroic stripe can be utilized for fabrication of integrated dual tunable functional devices for magnonic applications.

  7. Mn{sub 3}TeO{sub 6} - a new multiferroic material with two magnetic substructures

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Li; Hu, Zhiwei; Kuo, Chang-Yang; Tjeng, Liu Hao; Komarek, Alexander C. [Max-Planck-Institute for Chemical Physics of Solids, Dresden (Germany); Pi, Tun-Wen [National Synchrotron Radiation Research Center, Hsinchu (China); Wu, Maw-Kuen [Institute of Physics, Academia Sinica, Nankang, Taipei (China)

    2015-12-15

    From magnetic susceptibility, dielectric permittivity, electric polarization and specific heat measurements we discover spin-induced ferroelectricity and magnetoelectric coupling in Mn{sub 3}TeO{sub 6} and observe two successive magnetic transitions at low temperatures. A non-ferroelectric intermediate magnetic state occurs below 23 K and a multiferroic ground state emerges below 21 K. Moreover, Mn{sub 3}TeO{sub 6} is a candidate for a multiferroic material where two types of incommensurate spin structures, cycloidal and helical, coexist. Theoretically, both spin substructures may contribute to the macro electric polarization via different mechanisms. This could open new ways of manipulating the ferroelectric polarization in a multiferroic material. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. In-plane anisotropic effect of magnetoelectric coupled PMN-PT/FePt multiferroic heterostructure: Static and microwave properties

    Science.gov (United States)

    Vargas, Jose M.; Gómez, Javier

    2014-10-01

    The effects of the electric and magnetic field variation on multiferroic heterostructure were studied in this work. Thin films of polycrystalline Fe50Pt50 (FePt) were grown by dc-sputtering on top of the commercial slabs of lead magnesium niobate-lead titanate (PMN-PT). The sample was a (011)-cut single crystal and had one side polished. In this condition, the PMN-PT/FePt operates in the L-T (longitudinal magnetized-transverse polarized) mode. A FePt thin film of 20 nm was used in this study to avoid the characteristic broad microwave absorption line associated with these films above thicknesses of 40 nm. For the in-plane easy magnetization axis (01-1), a microwave magnetoelectric (ME) coupling of 28 Oe cm kV -1 was estimated, whereas a value of 42 Oe cm kV -1 was obtained through the hard magnetization axis (100). Insight into the effects of the in-plane strain anisotropy on the ME coupling is obtained from the dc-magnetization loops. It was observed that the trend was opposite along the easy and hard magnetic directions. In particular, along the easy-magnetic axis (01-1), a square and narrow loop with a factor of Mr/MS of 0.96 was measured at 10 kV/cm. Along the hard-magnetic axis, a factor of 0.16 at 10 kV/cm was obtained. Using electric tuning via microwave absorption at X-band (9.78 GHz), we observe completely different trends along the easy and hard magnetic directions; Multiple absorption lines along the latter axis compared to a single and narrower absorption line along the former. In spite of its intrinsic complexity, we propose a model which gives good agreement both for static and microwave properties. These observations are of fundamental interest for future ME microwave components, such as filters, phase-shifters, and resonators.

  9. In-plane anisotropic effect of magnetoelectric coupled PMN-PT/FePt multiferroic heterostructure: Static and microwave properties

    Directory of Open Access Journals (Sweden)

    Jose M. Vargas

    2014-10-01

    Full Text Available The effects of the electric and magnetic field variation on multiferroic heterostructure were studied in this work. Thin films of polycrystalline Fe50Pt50 (FePt were grown by dc-sputtering on top of the commercial slabs of lead magnesium niobate-lead titanate (PMN-PT. The sample was a (011-cut single crystal and had one side polished. In this condition, the PMN-PT/FePt operates in the L-T (longitudinal magnetized-transverse polarized mode. A FePt thin film of 20 nm was used in this study to avoid the characteristic broad microwave absorption line associated with these films above thicknesses of 40 nm. For the in-plane easy magnetization axis (01-1, a microwave magnetoelectric (ME coupling of 28 Oe cm kV −1 was estimated, whereas a value of 42 Oe cm kV −1 was obtained through the hard magnetization axis (100. Insight into the effects of the in-plane strain anisotropy on the ME coupling is obtained from the dc-magnetization loops. It was observed that the trend was opposite along the easy and hard magnetic directions. In particular, along the easy-magnetic axis (01-1, a square and narrow loop with a factor of Mr/MS of 0.96 was measured at 10 kV/cm. Along the hard-magnetic axis, a factor of 0.16 at 10 kV/cm was obtained. Using electric tuning via microwave absorption at X-band (9.78 GHz, we observe completely different trends along the easy and hard magnetic directions; Multiple absorption lines along the latter axis compared to a single and narrower absorption line along the former. In spite of its intrinsic complexity, we propose a model which gives good agreement both for static and microwave properties. These observations are of fundamental interest for future ME microwave components, such as filters, phase-shifters, and resonators.

  10. Observation of spontaneous ferroelectric polarization reversal in multiferroic Mn1-xNixWO4 (x ≈ 0.16)

    Science.gov (United States)

    Song, Young-Sang; Chung, Jae-Ho; Woo Shin, Kwang; Hoon Kim, Kee; Hwan Oh, In

    2014-06-01

    In this Letter, we report the effect of replacing Mn2+ ions with Ni2+ on the ferroelectricity of multiferroic MnWO4 single crystals. When the amount of substitution was close to 16%, the sign of ferroelectric polarization spontaneously became negative with respect to initial dc poling field at a few degrees below TC. Neutron diffraction intensities revealed a sudden change in the underlying spiral spin ordering that occurred coincidentally with the observed sign reversal. This unusual behavior in zero magnetic fields suggests that strong competitions between the two different magnetic ions may provide an efficient route to manipulation of existing multiferroics.

  11. Nonlinear phenomena in multiferroic nanocapacitor: Joule heating and electromechanical effects

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yunseok [ORNL; Kumar, Amit [ORNL; Tselev, Alexander [ORNL; Kravchenko, Ivan I [ORNL; Kalinin, Sergei V [ORNL; Jesse, Stephen [ORNL

    2011-01-01

    We demonstrate an approach for probing nonlinear electromechanical responses in BiFeO3 thin film nanocapacitors using half-harmonic band excitation piezoresponse force microscopy (PFM). Nonlinear PFM images of nanocapacitor arrays show clearly visible clusters of capacitors associated with variations of local leakage current through the BiFeO3 film. Strain spectroscopy measurements and finite element modeling point to significance of the Joule heating and show that the thermal effects caused by the Joule heating can provide nontrivial contributions to the nonlinear electromechanical responses in ferroic nanostructures. This approach can be further extended to unambiguous mapping of electrostatic signal contributions to PFM and related techniques.

  12. Sensitivity Enhancement in Magnetic Sensors Based on Ferroelectric-Bimorphs and Multiferroic Composites.

    Science.gov (United States)

    Sreenivasulu, Gollapudi; Qu, Peng; Petrov, Vladimir; Qu, Hongwei; Srinivasan, Gopalan

    2016-01-01

    Multiferroic composites with ferromagnetic and ferroelectric phases have been studied in recent years for use as sensors of AC and DC magnetic fields. Their operation is based on magneto-electric (ME) coupling between the electric and magnetic subsystems and is mediated by mechanical strain. Such sensors for AC magnetic fields require a bias magnetic field to achieve pT-sensitivity. Novel magnetic sensors with a permanent magnet proof mass, either on a ferroelectric bimorph or a ferromagnetic-ferroelectric composite, are discussed. In both types, the interaction between the applied AC magnetic field and remnant magnetization of the magnet results in a mechanical strain and a voltage response in the ferroelectric. Our studies have been performed on sensors with a Nd-Fe-B permanent magnet proof mass on (i) a bimorph of oppositely-poled lead zirconate titanate (PZT) platelets and (ii) a layered multiferroic composite of PZT-Metglas-Ni. The sensors have been characterized in terms of sensitivity and equivalent magnetic noise N. Noise N in both type of sensors is on the order of 200 pT/√Hz at 1 Hz, a factor of 10 improvement compared to multiferroic sensors without a proof mass. When the AC magnetic field is applied at the bending resonance for the bimorph, the measured N ≈ 700 pT/√Hz. We discuss models based on magneto-electro-mechanical coupling at low frequency and bending resonance in the sensors and theoretical estimates of ME voltage coefficients are in very good agreement with the data. PMID:26907290

  13. Investigation of multiferroic behaviour of TbMnO3 nanoplates

    International Nuclear Information System (INIS)

    Highlights: • Hydrothermal synthesis of TbMnO3 nanoplate. • Morphology induced defects detected by Raman spectroscopy. • Magnetic and dielectric anomalies confirmed multiferroic behavior is retained in TbMnO3 nanoplates. - Abstract: In the present study, hydrothermally prepared TbMnO3 in plates-like morphology at nanoscale are investigated in multiferroic view point. X-ray diffraction study confirms the orthorhombic phase of as-synthesized TbMnO3. Microstructural features studied by Scanning Electron Microscopy and Transmission Electron Microscopy show the plates-like morphology of as-synthesized TbMnO3 at nanoscale. Local distortions investigated by FT-Raman exhibits redshift in T mode by about 20 cm−1 as compared to that of the single crystal. The redshift in T mode is mainly due to defect by tilting of octahedra and respective changes in bond angle of Mn–O(1)–Mn. This is assigned to the size-morphology induced defects. The temperature dependent zero-field-cooled and field-cooled magnetization are measured at H = 50 Oe and in the temperature range 2–300 K. The anomalies in magnetization are obtained at 8 and 42 K. Bifurcation of the ZFC and FC curves are observed very close to magnetic transition temperature 42 K. The 42 K anomaly is related to the sine wave ordering of Mn3+ moment; and 8 K anomaly is associated with magnetic ordering of the Tb3+-sublattice propagation vector. The anomalies in the electric properties, ϵ′ (T), tan δ (T), which are noticed within the 28 K range, coincide with the temperature of incommensurate–commensurate (or lock-in) magnetic transition of TbMnO3. This study confirms that multiferroic behavior is retained in TbMnO3 nanoplates

  14. Sensitivity Enhancement in Magnetic Sensors Based on Ferroelectric-Bimorphs and Multiferroic Composites

    Science.gov (United States)

    Sreenivasulu, Gollapudi; Qu, Peng; Petrov, Vladimir; Qu, Hongwei; Srinivasan, Gopalan

    2016-01-01

    Multiferroic composites with ferromagnetic and ferroelectric phases have been studied in recent years for use as sensors of AC and DC magnetic fields. Their operation is based on magneto-electric (ME) coupling between the electric and magnetic subsystems and is mediated by mechanical strain. Such sensors for AC magnetic fields require a bias magnetic field to achieve pT-sensitivity. Novel magnetic sensors with a permanent magnet proof mass, either on a ferroelectric bimorph or a ferromagnetic-ferroelectric composite, are discussed. In both types, the interaction between the applied AC magnetic field and remnant magnetization of the magnet results in a mechanical strain and a voltage response in the ferroelectric. Our studies have been performed on sensors with a Nd-Fe-B permanent magnet proof mass on (i) a bimorph of oppositely-poled lead zirconate titanate (PZT) platelets and (ii) a layered multiferroic composite of PZT-Metglas-Ni. The sensors have been characterized in terms of sensitivity and equivalent magnetic noise N. Noise N in both type of sensors is on the order of 200 pT/√Hz at 1 Hz, a factor of 10 improvement compared to multiferroic sensors without a proof mass. When the AC magnetic field is applied at the bending resonance for the bimorph, the measured N ≈ 700 pT/√Hz. We discuss models based on magneto-electro-mechanical coupling at low frequency and bending resonance in the sensors and theoretical estimates of ME voltage coefficients are in very good agreement with the data. PMID:26907290

  15. Investigation of multiferroic behaviour of TbMnO{sub 3} nanoplates

    Energy Technology Data Exchange (ETDEWEB)

    Acharya, S.A., E-mail: saha275@yahoo.com; Khule, S.M.; Gaikwad, V.M.

    2015-07-15

    Highlights: • Hydrothermal synthesis of TbMnO{sub 3} nanoplate. • Morphology induced defects detected by Raman spectroscopy. • Magnetic and dielectric anomalies confirmed multiferroic behavior is retained in TbMnO{sub 3} nanoplates. - Abstract: In the present study, hydrothermally prepared TbMnO{sub 3} in plates-like morphology at nanoscale are investigated in multiferroic view point. X-ray diffraction study confirms the orthorhombic phase of as-synthesized TbMnO{sub 3}. Microstructural features studied by Scanning Electron Microscopy and Transmission Electron Microscopy show the plates-like morphology of as-synthesized TbMnO{sub 3} at nanoscale. Local distortions investigated by FT-Raman exhibits redshift in T mode by about 20 cm{sup −1} as compared to that of the single crystal. The redshift in T mode is mainly due to defect by tilting of octahedra and respective changes in bond angle of Mn–O(1)–Mn. This is assigned to the size-morphology induced defects. The temperature dependent zero-field-cooled and field-cooled magnetization are measured at H = 50 Oe and in the temperature range 2–300 K. The anomalies in magnetization are obtained at 8 and 42 K. Bifurcation of the ZFC and FC curves are observed very close to magnetic transition temperature 42 K. The 42 K anomaly is related to the sine wave ordering of Mn{sup 3+} moment; and 8 K anomaly is associated with magnetic ordering of the Tb{sup 3+}-sublattice propagation vector. The anomalies in the electric properties, ϵ′ (T), tan δ (T), which are noticed within the 28 K range, coincide with the temperature of incommensurate–commensurate (or lock-in) magnetic transition of TbMnO{sub 3.} This study confirms that multiferroic behavior is retained in TbMnO{sub 3} nanoplates.

  16. Identifying the Magnetoelectric Modes of Multiferroic BiFeO3

    Energy Technology Data Exchange (ETDEWEB)

    Fishman, Randy Scott [ORNL; Furukawa, N. [Aoyama Gakuin University, Kanagawa, Japan; Haraldsen, Jason T. [Los Alamos National Laboratory (LANL); Matsuda, Masaaki [ORNL; Miyahara, Shinya [Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea

    2012-01-01

    We have identified three of the four magnetoelectric modes of multiferroic BiFeO3 measured using THz spectroscopy. Excellent agreement with the observed peaks is obtained by including the effects of easy-axis anisotropy along the direction of the electric polarization. By distorting the cycloidal spin state, anisotropy splits the 1 mode into peaks at 20 and 21.5 cm 1 and activates the lower 2 mode at 27 cm 1 (T = 200 K). An electromagnon is identified with the upper 1 mode at 21.5 cm 1. Our results also explain recent Raman and inelastic neutron-scattering measurements.

  17. Magnetic and ferroelectric phase coexistence in multiferroic PFW-PT ceramics

    OpenAIRE

    Bárbara Fraygola; Adelino A. Coelho; Ducinei Garcia; José Antônio Eiras

    2012-01-01

    The multiferroic (1-x)PbFe2/3W1/3O3–xPbTiO3 solid solutions with various compositions x = 0, 0.10, 0.20 and 0.30 were investigated. The features of the relaxor-to-ferroelectric transition with increasing x were discussed based in connection with dielectric and ferroelectric proprieties. Different types of magnetic activity dependent on composition and temperature were found. The temperature of ferroelectric and antiferromagnetic phase coexistence was investigated in function of PT content, de...

  18. Polarity-tunable spin transport in all-oxide multiferroic tunnel junctions

    Science.gov (United States)

    Soni, Rohit; Petraru, Adrian; Nair, Harikrishnan S.; Vavra, Ondrej; Ziegler, Martin; Kim, Seong Keun; Jeong, Doo Seok; Kohlstedt, Hermann

    2016-05-01

    A multiferroic tunnel junction (MFTJ) promisingly offers multinary memory states in response to electric- and magnetic-fields, referring to tunneling electroresistance (TER) and tunneling magnetoresistance (TMR), respectively. In spite of recent progress, a substantial number of questions concerning the understanding of these two intertwined phenomena still remain open, e.g. the role of microstructural/chemical asymmetry at the interfaces of the junction and the effect of an electrode material on the MFTJ properties. In this regard, we look into the multiferroic effect of all-complex-oxide MFTJ (La0.7Sr0.3MnO3/Pb(Zr0.3Ti0.7)O3/La0.7Sr0.3MnO3). The results reveal apparent TER-TMR interplay--captured by the reversible electric-field control of the TMR effect. Finally, microscopy analysis on the MFTJ revealed that the observed TER-TMR interplay is perhaps mediated by microstructural and chemical asymmetry in our nominally symmetric MFTJ.A multiferroic tunnel junction (MFTJ) promisingly offers multinary memory states in response to electric- and magnetic-fields, referring to tunneling electroresistance (TER) and tunneling magnetoresistance (TMR), respectively. In spite of recent progress, a substantial number of questions concerning the understanding of these two intertwined phenomena still remain open, e.g. the role of microstructural/chemical asymmetry at the interfaces of the junction and the effect of an electrode material on the MFTJ properties. In this regard, we look into the multiferroic effect of all-complex-oxide MFTJ (La0.7Sr0.3MnO3/Pb(Zr0.3Ti0.7)O3/La0.7Sr0.3MnO3). The results reveal apparent TER-TMR interplay--captured by the reversible electric-field control of the TMR effect. Finally, microscopy analysis on the MFTJ revealed that the observed TER-TMR interplay is perhaps mediated by microstructural and chemical asymmetry in our nominally symmetric MFTJ. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01277a

  19. Analysis of the multiferroicity in the hexagonal manganite YMnO3

    International Nuclear Information System (INIS)

    We performed magnetic and ferroelectric measurements, associated with Landau theory and symmetry analysis, in order to clarify the situation of the YMnO3 system, a classical example of type I multiferroics. We found that the only magnetic group compatible with all experimental data (neutron scattering, magnetization, polarization, dielectric constant, second harmonic generation) is the P63' group. In this group a small ferromagnetic component along c is induced by the Dzyaloshinskii–Moriya interaction, and observed here in magnetization measurements. We found that the ferromagnetic and antiferromagnetic components can only be switched simultaneously, while the magnetic orders are functions of the polarization square and therefore insensitive to its sign. (paper)

  20. Nanoscale control of exchange bias with BiFeO3 thin films

    OpenAIRE

    Martin, Lane W.; Chu, Ying-Hao; Mikel B. Holcomb; Huijben, Mark; Han, Shu-Jen; Lee, Donkoun; Wang, Shan X.; Ramesh, R.

    2008-01-01

    We demonstrate a direct correlation between the domain structure of multiferroic BiFeO3 thin films and exchange bias of Co0.9Fe0.1/BiFeO3 heterostructures. Two distinct types of interactions, an enhancement of the coercive field (exchange enhancement) and an enhancement of the coercive field combined with large shifts of the hysteresis loop (exchange bias), have been observed in these heterostructures, which depend directly on the type and crystallography of the nanoscale (2 nm) domain walls ...

  1. Possible coupling between magnons and phonons in multiferroic CaMn.sub.7./sub.O.sub.12./sub..

    Czech Academy of Sciences Publication Activity Database

    Kadlec, Filip; Goian, Veronica; Kadlec, Christelle; Kempa, Martin; Vaněk, Přemysl; Taylor, J.; Rols, S.; Prokleška, J.; Orlita, M.; Kamba, Stanislav

    2014-01-01

    Roč. 90, č. 5 (2014), "054307-1"-"054307-8". ISSN 1098-0121 R&D Projects: GA ČR GAP204/12/1163 Institutional support: RVO:68378271 Keywords : electromagnons * phonons * multiferroics * THz and IR spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  2. Peculiar features of the dielectric response in lead scandium tantalate Pb(Sc.sub.1/2./sub.Ta.sub.1/2./sub.)O.sub.3./sub. thin films

    Czech Academy of Sciences Publication Activity Database

    Kyle, B.; Tagantsev, A.; Cherman, V.; Wang, Y.; Setter, N.; Kamba, Stanislav; Petzelt, Jan

    Warrendale: Materials Research Society, 2007, T07/37/1-T07/37/5. (MRS Symposium Proceedings. 966E). ISBN N. [Ferroelectrics and Multiferroics. Boston (US), 27.11.2006-01.12.2006] R&D Projects: GA ČR(CZ) GA202/06/0403 Institutional research plan: CEZ:AV0Z10100520 Keywords : relaxor ferroelectric * dielectric dispersion * thin films Subject RIV: BM - Solid Matter Physics ; Magnetism

  3. Synthesis of magnetic and multiferroic materials from polyvinyl alcohol-based gels

    Science.gov (United States)

    Lisnevskaya, I. V.; Bobrova, I. A.; Lupeiko, T. G.

    2016-01-01

    This review article summarizes results on the synthesis of the magnetic materials including modified nickel ferrite (Ni0.9Co0.1Cu0.1Fe1.9O4-δ), yttrium iron garnet (Y3Fe5O12), lanthanum-containing manganites (MxLa1-xMnO3 (M=Pb, Ba or Sr; x=0.3-0.35)), and multiferroics (BiFeO3 and BiFe0.5Mn0.5O3) from polyvinyl alcohol-based gels. It is shown that the ammonium nitrate accelerates destruction of organic components of xerogels and thus Ni0.9Co0.1Cu0.1Fe1.9O4-δ and BiFeO3 can be prepared at record low temperatures (100 and 250 °C, respectively) which are 200-300 °C lower compared to the process where air is used as an oxidizing agent. As for the synthesis of Y3Fe5O12, MxLa1-xMnO3 and BiFe0.5Mn0.5O3, the presence of NH4NO3 favors formation of foreign phases, which ultimately complicate reaction mechanisms and lead to the higher temperature to synthesize target products. Developed methods provide nanoscale magnetic and multiferroic materials with an average particle size of ∼20-50 nm.

  4. Ion-beam synthesis and the studies of nanocomposite multiferroics based on barium titanate

    International Nuclear Information System (INIS)

    Co+ and Fe+ ions were implanted into single-crystalline barium titanate (BaTiO3) with fluences of (0.5−1.5)x1017 ion/cm2 to synthesize new multiferroic materials. High-fluence 3d-ion implantation results in the formation of Co (or Fe) nanoparticles with sizes of 5-10 nm in the irradiated layer of BaTiO3. With increasing the fluence both Co- and Fe-implanted BaTiO3 samples reveal at first superparamagnetic, and then ferromagnetic properties at room temperature. The strong shift of ferromagnetic resonance line under dc electric field and magnetocapacitance effects were observed in Co-implanted BaTiO3. These observations are a good evidence of the magnetoelectric coupling in Co-implanted BaTiO3. Our investigations show that ion implantation can be used to synthesize multiferroic composite materials like Co:BaTiO3 and Fe:BaTiO3. (authors)

  5. Magnetization dynamics and frustration in the multiferroic double perovskite Lu2MnCoO6

    Science.gov (United States)

    Zapf, Vivien S.; Ueland, B. G.; Laver, Mark; Lonsky, Martin; Pohlit, Merlin; Müller, Jens; Lancaster, Tom; Möller, Johannes S.; Blundell, Stephen J.; Singleton, John; Mira, Jorge; Yañez-Vilar, Susana; Señarís-Rodríguez, Maria Antonia

    2016-04-01

    We investigate the magnetic ordering and the magnetization dynamics (from kHz to THz time scales) of the double perovskite Lu2MnCoO6 using elastic neutron diffraction, muon spin relaxation, and micro-Hall magnetization measurements. This compound is known to be a type II multiferroic with the interesting feature that a ferromagneticlike magnetization hysteresis loop couples to an equally hysteretic electric polarization in the bulk of the material despite a zero-field magnetic ordering of the type ↑↑↓↓ along Co-Mn spin chains. Here we explore the unusual dynamics of this compound and find extremely strong fluctuations, consistent with the axial next-nearest-neighbor Ising (ANNNI) model for frustrated spin chains. We identify three temperature scales in Lu2MnCoO6 corresponding to the onset of highly fluctuating long-range order below TN=50 ±3 K identified from neutron scattering, the onset of magnetic and electric hysteresis, with change in kHz magnetic and electric dynamics below a 30 K temperature scale, and partial freezing of ˜MHz spin fluctuations in the muon spin relaxation data below 12 ±3 K. Our results provide a framework for understanding the multiferroic behavior of this compound and its hysteresis and dynamics.

  6. Magnetic and dielectric studies of multiferroic CuO nanoparticles confined to porous glass

    International Nuclear Information System (INIS)

    Dc magnetization and ac electric permittivity were measured for the CuO-porous glass nanocomposite made and for pressed powder CuO. Magnetization curves showed a bend between two linear segments for both the nanocomposite and bulk cupric oxide at 230 K evidencing that the temperature of the transition from the paramagnetic into multiferroic phase did not change noticeably under nanoconfinement. Results suggested also a reduction of the temperature of the second transition into the collinear antiferromagnetic phase. ZFC and FC magnetizations were found to bifurcate for the nanocomposite and bulk CuO. The bifurcation was accompanied with peaks on ZFC magnetization. - Highlights: ► CuO nanoparticles embedded into porous glass compared to bulk. ► ZFC and FC magnetizations bifurcate in the nanocomposite and bulk CuO. ► Dc magnetization suggests a reduction of the temperature TN1 till about 190 K. ► Temperature TN2 of the transition into multiferroic phase did not change.

  7. Nanoscale Skyrmions in a Nonchiral Metallic Multiferroic: Ni2MnGa.

    Science.gov (United States)

    Phatak, Charudatta; Heinonen, Olle; De Graef, Marc; Petford-Long, Amanda

    2016-07-13

    Magnetic skyrmions belong to a set of topologically nontrivial spin textures at the nanoscale that have received increased attention due to their emergent behavior and novel potential spintronic applications. Discovering materials systems that can host skyrmions at room temperature in the absence of external magnetic field is of crucial importance not only from a fundamental aspect, but also from a technological point of view. So far, the observations of skyrmions in bulk metallic ferromagnets have been limited to low temperatures and to materials that exhibit strong chiral interactions. Here we show the formation of nanoscale skyrmions in a nonchiral multiferroic material, which is ferromagnetic and ferroelastic, Ni2MnGa at room temperature without the presence of external magnetic fields. By using Lorentz transmission electron microscopy in combination with micromagnetic simulations, we elucidate their formation, behavior, and stability under applied magnetic fields at room temperature. The formation of skyrmions in a multiferroic material with no broken inversion symmetry presents new exciting opportunities for the exploration of the fundamental physics of topologically nontrivial spin textures. PMID:27186990

  8. Analysis of magnetic correlations in layered or multiferroic transition element oxides using neutron diffraction

    International Nuclear Information System (INIS)

    Due to a great variety of physical phenomena the material class of transition metal oxides offers a large field of work for researchers, the more so as many underlying mechanisms are not understood yet. Of these materials a set of systems closely related to the manganates is investigated in this thesis via neutron scattering, emphasizing the analysis of magnetic correlations. It is shown, that for doping concentrations 0 ≤ x ≤ 0.5 the Co2+-ions in the layered cobaltates always exhibit a high-spin state with S = (3)/(2), whereas existing Co3+-ions adopt a low-spin state with S = 0 and stay non-magnetic. Furthermore, the magnetic correlations of three chiral multiferroics are investigated: Firstly, in MnWO4 a memory effect is described; the crystal remembers its preceding chiral state even in the paramagnetic phase. In TbMnO3 chiral fluctuations slightly above the multiferroic transition are investigated; it is possible to switch them by an applied external E-field. Finally, in DyMnO3 the magnetic excitations are examined for the first time; they are comparable to those in TbMnO3.

  9. The properties of isolated chiral skyrmions in thin magnetic films

    Science.gov (United States)

    Leonov, A. O.; Monchesky, T. L.; Romming, N.; Kubetzka, A.; Bogdanov, A. N.; Wiesendanger, R.

    2016-06-01

    Axisymmetric solitonic states (chiral skyrmions) were first predicted theoretically more than two decades ago. However, until recently they have been observed in a form of skyrmionic condensates (hexagonal lattices and other mesophases). In this paper we report experimental and theoretical investigations of isolated chiral skyrmions discovered in PdFe/Ir(111) bilayers two years ago by Romming et al (2013 Science 341 636). The results of spin-polarized scanning tunneling microscopy analyzed within the continuum and discrete models provide a consistent description of isolated skyrmions in thin layers. The existence region of chiral skyrmions is restricted by strip-out instabilities at low fields and a collapse at high fields. We demonstrate that the same equations describe axisymmetric localized states in all condensed matter systems with broken mirror symmetry, and thus our findings establish basic properties of isolated skyrmions common for chiral liquid crystals, different classes of noncentrosymmetric magnets, ferroelectrics, and multiferroics.

  10. Resistive switching in polycrystalline YMnO3 thin films

    Directory of Open Access Journals (Sweden)

    A. Bogusz

    2014-10-01

    Full Text Available We report a unipolar, nonvolatile resistive switching in polycrystalline YMnO3 thin films grown by pulsed laser deposition and sandwiched between Au top and Ti/Pt bottom electrodes. The ratio of the resistance in the OFF and ON state is larger than 103. The observed phenomena can be attributed to the formation and rupture of conductive filaments within the multiferroic YMnO3 film. The generation of conductive paths under applied electric field is discussed in terms of the presence of grain boundaries and charged domain walls inherently formed in hexagonal YMnO3. Our findings suggest that engineering of the ferroelectric domains might be a promising route for designing and fabrication of novel resistive switching devices.

  11. Origin of the giant linear magnetoelectric effect in perovskitelike multiferroic BiFeO3

    Science.gov (United States)

    Popkov, A. F.; Davydova, M. D.; Zvezdin, K. A.; Solov'yov, S. V.; Zvezdin, A. K.

    2016-03-01

    In this article the mechanism of the linear magnetoelectric (ME) effect in the rhombohedral multiferroic BiFeO3 is considered. The study is based on the symmetry approach of the Ginzburg-Landau type, in which polarization, antiferrodistortion, and antiferromagnetic momentum vectors are viewed as ordering parameters. We demonstrate that the linear ME effect in BFO is caused by reorientation of the antiferrodistortion vector in either electric or magnetic field. The numerical estimations, which show quantitative agreement with the results of the recent measurements in film samples, have been performed. A possibility of significant enhancement of the magnetoelectric effect by applying an external static electric field has been investigated. The considered approach is promising for explaining the high values of the ME effect in composite films and heterostructures with BFO.

  12. Terahertz spectroscopy of spin waves in multiferroic BiFeO3 in high magnetic

    Energy Technology Data Exchange (ETDEWEB)

    Nagel, U. [National Institute of Chemical Physics and Biophysics, Estonia; Fishman, Randy Scott [ORNL; Katuwal, T. [National Institute of Chemical Physics and Biophysics, Estonia; Engelkamp, H. [Radboud University Nijmegen, The Netherlands; Talbayev, D. [Tulane University; Yi, Hee Tack [Rutgers University; Cheong, Sang-Wook [Rutgers University; Room, T. [National Institute of Chemical Physics and Biophysics, Estonia

    2013-01-01

    We have studied the magnetic eld dependence of far-infrared active magnetic modes in a single ferroelectric domain BiFeO3 crystal at low temperature. The modes soften close to the critical eld of 18.8T along the [001] (pseudocubic) axis, where the cycloidal structure changes to the homogeneous canted antiferromagnetic state and a new strong mode with linear eld dependence appears that persists at least up to 31 T. A microscopic model that includes two Dzyaloshinskii-Moriya interactions and easy-axis anisotropy describes closely both the zero-eld spectroscopic modes as well as their splitting and evolution in a magnetic eld. The good agreement of theory with experiment suggests that the proposed model provides the foundation for future technological applications of this multiferroic material.

  13. Orientation Dependence of the Critical Magnetic Field for Multiferroic BiFeO3

    Energy Technology Data Exchange (ETDEWEB)

    Fishman, Randy Scott [ORNL

    2013-01-01

    Multiferroic BiFeO3 undergoes a transition from a distorted spiral phase to a G-type antiferromagnet above a critical field Hc that depends on the orientation m of the field. We show that Hc(m) has a maximum when oriented along a cubic diagonal parallel to the electric polarization P and a minimum in the equatorial plane normal to P when two magnetic domains with the highest critical fields are degenerate. The measured critical field along a cubic axis is about 19 T but Hc is predicted to vary by as much as 2.5 T above and below this value. The orientational dependence of Hc(m) is more complex than indicated by earlier work, which did not consider the competition between magnetic domains.

  14. Field dependence of the Spin State and Spectroscopic Modes of Multiferroic BiFeO3

    Energy Technology Data Exchange (ETDEWEB)

    Fishman, Randy Scott [ORNL

    2013-01-01

    The spectroscopic modes of BiFeO3 provide detailed information about the very small anisotropy and Dzyaloshinskii-Moriya (DM) interactions responsible for the long-wavelength, distorted cycloid that appears below TN = 640 K. A microscopic model that includes two DM interactions and easyaxis anisotropy is able to closely describe both the zero-field spectroscopic modes as well as their splitting and evolution in a magnetic field. While only six modes are optically active in zero field, all of the zone-center modes are activated by a magnetic field. The close agreement with experiment suggests that the proposed model provides the foundation for future technological applications of this multiferroic material.

  15. Electric field control of spin transfer torque in multiferroic tunnel junctions

    Science.gov (United States)

    Useinov, Artur; Kalitsov, Alan; Velev, Julian; Kioussis, Nicholas

    2014-03-01

    Based on model calculations we predict that the spin transfer torque (STT) in magnetic tunnel junctions with ferroelectric barriers can be strongly influenced by the saturated polarization of the barrier. The STT in such multiferroic tunnel junctions is calculated within the non-equilibrium Keldysh formalism generalized for non-collinear transport and implemented in the framework of a single-band tight-binding (TB) model. We calculate the bias dependence of both the in-plane (T∥) and out-of-plane (T⊥) components of STT as a function of the ferroelectric polarization (P) in the barrier. We find that the components of STT strongly depend on both the magnitude and the direction of the polarization. In particular switching of the polarization direction can dramatically alter the value of the STT and can even lead to a change of sign of T∥ and the voltage-induced part of T⊥. The effect is proportional to the magnitude of the polarization.

  16. Ferroelectric control of spin-transfer torque in multiferroic tunnel junctions

    Science.gov (United States)

    Useinov, Artur; Kalitsov, Alan; Velev, Julian; Kioussis, Nicholas

    2015-03-01

    Based on model calculations we predict electric-field control of the spin-transfer torque (STT) in magnetic tunnel junctions with ferroelectric barriers. We demonstrate that the bias dependence of the in-plane T∥ and out-of-plane T⊥ components of the STT can be dramatically modified by the ferroelectric polarization. In particular, the magnitude of the STT can be enhanced or suppressed by switching the polarization direction and in some cases the sign of STT can be toggled. The underlying mechanism is the combination of polarization-induced symmetry breaking and the interplay of the bias-induced and polarization-induced spin-dependent screening giving rise to a rich behavior of the electrostatic potential energy profile. These properties could lead to enhanced switching efficiency in STT-based devices and open a new avenue for applications of multiferroic devices.

  17. Microstructural, dielectric and magnetic properties of multiferroic composite system barium strontium titanate – nickel cobalt ferrite

    International Nuclear Information System (INIS)

    Multiferroic composites (1-x) Ba0.95Sr0.05TiO3 + (x) Ni0.8Co0.2Fe2O4 (where x = 0.1, 0.2, 0.3, 0.4) has been prepared by solid state reaction method. X-ray diffraction analysis of the composite samples confirmed the presence of both barium strontium titanate (BST) and nickel cobalt ferrite (NCF) phases. FESEM images indicated the well dispersion of NCF grains among BST grains. Dielectric constant and loss of the composite samples decreases with increase in frequency following Maxwell-Wagner relaxation mechanism. Composite sample with highest ferrite content possesses highest values of remanent and saturation magnetization

  18. Microstructural, dielectric and magnetic properties of multiferroic composite system barium strontium titanate – nickel cobalt ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Pahuja, Poonam, E-mail: poonampahuja123@gmail.com; Tandon, R. P., E-mail: ram-tandon@hotmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi-110007 (India)

    2015-05-15

    Multiferroic composites (1-x) Ba{sub 0.95}Sr{sub 0.05}TiO{sub 3} + (x) Ni{sub 0.8}Co{sub 0.2}Fe{sub 2}O{sub 4} (where x = 0.1, 0.2, 0.3, 0.4) has been prepared by solid state reaction method. X-ray diffraction analysis of the composite samples confirmed the presence of both barium strontium titanate (BST) and nickel cobalt ferrite (NCF) phases. FESEM images indicated the well dispersion of NCF grains among BST grains. Dielectric constant and loss of the composite samples decreases with increase in frequency following Maxwell-Wagner relaxation mechanism. Composite sample with highest ferrite content possesses highest values of remanent and saturation magnetization.

  19. A phenomenological theory for polarization flop in spiral multiferroic TbMnO$_3$

    Indian Academy of Sciences (India)

    Tiwari Shruti; Sa Debanand

    2016-04-01

    A phenomenological Landau theory has been used to explain magnetic field-driven polarization flop in TbMnO3. The Néel wall-like magnetic structure in spiral multiferroics induces a space-dependent internal magnetic field which exerts a torque on spins to rotate bc-spiral to abspiral. The external magnetic field is argued to be competing with easy axis anisotropy and the system stabilizes when anisotropy is minimum.With the help of Landau free energy with DM magnetoelectric coupling and a general ansatz for magnetization, the phenomenon of polarization flop has been explained. Relation between Tflop and critical magnetic field has been established and found to be in good agreement with the experiment. This could be an indication that anisotropy ofthe system is temperature- and magnetic field-dependent.

  20. Stress-mediated magnetoelectric control of ferromagnetic domain wall position in multiferroic heterostructures

    Science.gov (United States)

    Mathurin, Théo; Giordano, Stefano; Dusch, Yannick; Tiercelin, Nicolas; Pernod, Philippe; Preobrazhensky, Vladimir

    2016-02-01

    The motion of a ferromagnetic domain wall in nanodevices is usually induced by means of external magnetic fields or polarized currents. Here, we demonstrate the possibility to reversibly control the position of a Néel domain wall in a ferromagnetic nanostripe through a uniform mechanical stress. The latter is generated by an electro-active substrate combined with the nanostripe in a multiferroic heterostructure. We develop a model describing the magnetization distribution in the ferromagnetic material, properly taking into account the magnetoelectric coupling. Through its numerical implementation, we obtain the relationship between the electric field applied to the piezoelectric substrate and the position of the magnetic domain wall in the nanostripe. As an example, we analyze a structure composed of a PMN-PT substrate and a TbCo2/FeCo composite nanostripe.

  1. Dynamic in situ visualization of voltage-driven magnetic domain evolution in multiferroic heterostructures

    Science.gov (United States)

    Gao, Ya; Hu, Jia-Mian; Wu, Liang; Nan, C. W.

    2015-12-01

    Voltage control of magnetism in multiferroic heterostructures provides a promising solution to the excessive heating in spintronic devices. Direct observation of voltage-modulated magnetic domain evolution dynamics is desirable for studying the mechanism of the voltage control of magnetism at mesoscale, but has remained challenging. Here we explored a characterization method for the dynamic in situ evolution of pure voltage modulated magnetic domains in the heterostructures by employing the scanning Kerr microscopy function in the magneto optic Kerr effect system. The local magnetization reorientation of a Ni/PMN-PT heterostructure were characterized under sweeping applied voltage on the PMN-PT single crystal, and the results show that the magnetization rotation angle in the local regions is much greater than that obtained from macroscopic magnetization hysteresis loops.

  2. Dynamic in situ visualization of voltage-driven magnetic domain evolution in multiferroic heterostructures

    International Nuclear Information System (INIS)

    Voltage control of magnetism in multiferroic heterostructures provides a promising solution to the excessive heating in spintronic devices. Direct observation of voltage-modulated magnetic domain evolution dynamics is desirable for studying the mechanism of the voltage control of magnetism at mesoscale, but has remained challenging. Here we explored a characterization method for the dynamic in situ evolution of pure voltage modulated magnetic domains in the heterostructures by employing the scanning Kerr microscopy function in the magneto optic Kerr effect system. The local magnetization reorientation of a Ni/PMN-PT heterostructure were characterized under sweeping applied voltage on the PMN-PT single crystal, and the results show that the magnetization rotation angle in the local regions is much greater than that obtained from macroscopic magnetization hysteresis loops. (paper)

  3. Electric-field-driven magnetization reversal in square-shaped nanomagnet-based multiferroic heterostructure

    International Nuclear Information System (INIS)

    Based on phase field modeling and thermodynamic analysis, purely electric-field-driven magnetization reversal was shown to be possible in a multiferroic heterostructure of a square-shaped amorphous Co40Fe40B20 nanomagnet on top of a ferroelectric layer through electrostrain. The reversal is made possible by engineering the mutual interactions among the built-in uniaxial magnetic anisotropy, the geometry-dependent magnetic configuration anisotropy, and the magnetoelastic anisotropy. Particularly, the incorporation of the built-in uniaxial anisotropy made it possible to reverse magnetization with one single unipolar electrostrain pulse, which is simpler than previous designs involving the use of bipolar electrostrains and may alleviate ferroelectric fatigue. Critical conditions for triggering the magnetization reversal are identified

  4. Pressure-induced phase transitions of multiferroic BiFeO3

    International Nuclear Information System (INIS)

    Pressure-induced phase transitions of multiferroic BiFeO3 have been investigated using synchrotron radiation X-ray diffraction with diamond anvil cell technique at room temperature. Present experimental data clearly show that rhombohedral (R3c) phase of BiFeO3 first transforms to monoclinic (C2/m) phase at 7 GPa, then to orthorhombic (Pnma) phase at 11 GPa, which is consistent with recent theoretical ab initio calculation. However, we observe another peak at 2θ=7° in the pressure range of 5-7 GPa that has not been reported previously. Further analysis reveals that this reflection peak is attributed to the orthorhombic (Pbam) phase, indicating the coexistence of monoclinic phase with orthorhombic phase in low pressure range. (authors)

  5. X-ray diffraction studies on multiferroic RMnO3 compounds in high magnetic fields

    International Nuclear Information System (INIS)

    Investigations of the multiferroic compounds TbMnO3, DyMnO3 and Y0.2Eu0.8MnO3 by x-ray diffraction in high magnetic fields, oriented along the a and b-directions of the crystal, are presented. The relation of the behaviour of first and second harmonic reflections to changes in ordering of the rare earth moments in applied field for TbMnO3 and DyMnO3 is discussed. Observations below the ordering temperature of the rare earth moments without and with applied magnetic field suggests a strong interaction of the rare earth moments, the Mn moments and the lattice. Since structural first harmonic reflections are absent in Y0.2Eu0.8MnO3, these reflections in the other compounds reflect the ordering of the rare earth moments.

  6. Dynamic in situ visualization of voltage-driven magnetic domain evolution in multiferroic heterostructures.

    Science.gov (United States)

    Gao, Ya; Hu, Jia-Mian; Wu, Liang; Nan, C W

    2015-12-23

    Voltage control of magnetism in multiferroic heterostructures provides a promising solution to the excessive heating in spintronic devices. Direct observation of voltage-modulated magnetic domain evolution dynamics is desirable for studying the mechanism of the voltage control of magnetism at mesoscale, but has remained challenging. Here we explored a characterization method for the dynamic in situ evolution of pure voltage modulated magnetic domains in the heterostructures by employing the scanning Kerr microscopy function in the magneto optic Kerr effect system. The local magnetization reorientation of a Ni/PMN-PT heterostructure were characterized under sweeping applied voltage on the PMN-PT single crystal, and the results show that the magnetization rotation angle in the local regions is much greater than that obtained from macroscopic magnetization hysteresis loops. PMID:26613293

  7. Determination of the cation site distribution of the spinel in multiferroic CoFe{sub 2}O{sub 4}/BaTiO{sub 3} layers by X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Aghavnian, T. [CEA/Saclay, DSM/IRAMIS/SPEC, CNRS UMR 3680, F-91191 Gif-sur-Yvette (France); Synchrotron SOLEIL, L’Orme des Merisiers Saint-Aubin, F-91192 Gif-sur-Yvette (France); Moussy, J.-B.; Stanescu, D. [CEA/Saclay, DSM/IRAMIS/SPEC, CNRS UMR 3680, F-91191 Gif-sur-Yvette (France); Belkhou, R. [Synchrotron SOLEIL, L’Orme des Merisiers Saint-Aubin, F-91192 Gif-sur-Yvette (France); Jedrecy, N. [Sorbonne Universités, UPMC Univ Paris 06, UMR 7588, INSP, F-75005 Paris (France); Magnan, H. [CEA/Saclay, DSM/IRAMIS/SPEC, CNRS UMR 3680, F-91191 Gif-sur-Yvette (France); Ohresser, P. [Synchrotron SOLEIL, L’Orme des Merisiers Saint-Aubin, F-91192 Gif-sur-Yvette (France); Arrio, M.-A.; Sainctavit, Ph. [IMPMC, F-75015 Paris (France); Barbier, A., E-mail: abarbier@cea.fr [CEA/Saclay, DSM/IRAMIS/SPEC, CNRS UMR 3680, F-91191 Gif-sur-Yvette (France)

    2015-07-15

    Highlights: • We grow epitaxial and well characterized CoFe{sub 2}O{sub 4}/BaTiO{sub 3} thin films. • We studied the spinel cation site distribution in CoFe{sub 2}O{sub 4}/BaTiO{sub 3} thin films. • We quantitatively determine the spinel inversion parameter by XMCD and XPS. • We propose a reproducible XPS fit method based on physical principles. - Abstract: The properties of CoFe{sub 2}O{sub 4}/BaTiO{sub 3} artificial multiferroic multilayers strongly depend on the crystalline structure, the stoichiometry and the cation distribution between octahedral (Oh) and tetrahedral (Td) sites (inversion factor). In the present study, we have investigated epitaxial CoFe{sub 2}O{sub 4} layers grown on BaTiO{sub 3}, with different Co/Fe ratios. We determined the cation distribution in our samples by X-ray magnetic circular dichroism (XMCD), a well accepted method to do so, and by X-ray photoelectron spectroscopy (XPS), using a fitting method based on physical considerations. We observed that our XPS approach converged on results consistent with XMCD measurements made on the same samples. Thus, within a careful decomposition based on individual chemical environments it is shown that XPS is fully able to determine the actual inversion factor.

  8. Neutron powder diffraction experiments on multiferroic DyMnO3

    International Nuclear Information System (INIS)

    Multiferroic materials of particular interest are the frustrated magnetic compounds that exhibit a strongly coupled electric polarization (EP). One such compound is DyMnO3 which exists in an orthorhombic (o-DMO) and hexagonal modification depending on the synthesis conditions. In the present work the o-DMO is investigated by means of neutron powder diffraction focusing on the magnetic phase transitions and the behavior of the structural parameters in different magnetic and multiferroic phases. Below Tn,mn =39 K, the Mn moments order sinusoidally with no EP. Then Tl=16 K the Mn moments order in a spin spiral structure with an induced Dy moment and EP and finally below TN,DY=9 K a collinear ordering of the Dy moments takes place that reduces the EP significantly. Single phase samples are prepared via the solid state route and neutron diffraction (ND) experiments are carried out at the high flux ND beamline Wombat and at the high resolution ND beamline Echidna at OPAL. 0-DMO crystallizes in the space group Pbnm. All three magnetic phase transitions are identified and are in good agreement with. Below TN,MN an increased rotation of the rigid Mn06 octahedra in the ab plane, likely due to the competition between nearest neighbour aid next nearest neighbour superexchange interactions takes place. However below Tl the MnO6 octahedra are significantly distorted along the c axis, the direction of the EP. Therefore the correlation between significant changes in the Mn-O bonds and the spontaneous EP are evident below Tl. The reduction of EP below TN.DY on the other hand correlates with the rapid increase in the orbital ordering angle towards the 120° corresponding to the 3x2-r2/3y2-r2 character of the orbitals.

  9. Multiferroic properties of Tb-doped BiFeO{sub 3} nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Lotey, Gurmeet Singh, E-mail: gslotey1986@gmail.com; Verma, N. K. [School of Physics and Materials Science, Thapar University, Nano Research Lab (India)

    2013-04-15

    Nanoscale, multifunctional, multiferroic materials possess strong magnetoelectric coupling (ME), open exciting multitudinous ways for designing future nanoelectronic and spintronic device applications. Bulk nanowires (100 nm), pure, and Tb-doped BiFeO{sub 3} multiferroic nanowires (20 nm) have been synthesized by colloidal dispersion template-assisted technique. The effects of Tb-doping and size of synthesized nanowires on structural, electrical, magnetic, dielectric, and magnetodielectric properties have been investigated. X-ray diffraction study reveals that doping of Tb in BiFeO{sub 3} nanowires leads to structural transformation from rhombohedral to orthorhombic. X-ray photoemission analysis confirms the +3 oxidation state of Fe and high purity of samples. Bulk nanowires exhibit antiferromagnetic characteristics, whereas the Tb-doped BiFeO{sub 3} nanowires show ferromagnetic character. Moreover, with increase in Tb concentration, the saturation magnetization increases. Temperature-dependent magnetization study suggests their size-dependent ferro and ferri-magnetic behavior. Polarization versus electric field (P-E) study reveals that pure BiFeO{sub 3} nanowires possess elliptical loop; however, doping of Tb results in rectangular loop- portentous good ferroelectric properties. All synthesized samples exhibit frequency-dependent dielectric constant which decreases with increase in frequency and remains fairly constant at higher frequencies. Leakage current density decreases with increase in Tb concentration, and has been found to be three orders of magnitude less than those of bulk BiFeO{sub 3} nanowires. The ME coupling in synthesized nanowires was estimated by measuring magnetodielectric. A very high value of ME, 7.2 %, has been found for 15 % Tb-doped BiFeO{sub 3} nanowires. In this communication, we, for the first time, report new cue on size-dependent Tb-doped BiFeO{sub 3} nanowires, which may be further used to explore its technological device applications.

  10. Synthesis and multiferroic properties of M-type SrFe12O19 hexaferrite ceramics

    International Nuclear Information System (INIS)

    Highlights: • SrFe12O19-hexaferrites show strong room-temperature multiferroic properties. • Modified ceramic technique helps to increase resistivity of hexaferrites. • Large spontaneous polarisation is observed in single-phase SrFe12O19. • External electric field deceases the remanent magnetisation of SrFe12O19 by 10%. - Abstract: The coexistence of strong ferromagnetism and large ferroelectricity has been observed in pure strontium hexaferrite SrFe12O19 fabricated by a modified ceramic technological method from highly purified initial materials with addition of boron oxide in mass concentration of less than 1.5%. The structure of the samples confirmed by X-ray diffraction patterns is consistent with a single hexagonal phase. The samples were polycrystalline with the grain size of 300–400 nm and the intergrain space was field with B2O3. The use of boron oxide resulted in enhanced resistivity enabling proper electric polarisation measurements. The magnetic properties are characterised by a standard ferrimagnetic behaviour with the Neel temperature of about 450 °C. Large electric polarisation was observed with the remnant value of 22 μC/cm2 and the maximal value of 45 μC/cm2 under the electric field of 300 kV/m. A strong coupling between magnetic and electric ordering was confirmed by measuring the magnetoelectric parameter and the electric field-controlled magnetic hysteresis. The change in magnetization by applying an electric field was in the range of 9–10%, which is even greater than that observed in some substituted hexaferrites with a magnetically induced electric polarisation. The combination of room-temperature multiferroic properties and electrically tuneable magnetization is promising for applications in magnetoelectric devices

  11. Magnetoelectic multiferroic superlattices and interfaces: Designing spintronic materials from first principles

    Science.gov (United States)

    Zanolli, Zeila

    2015-03-01

    The research challenges of the near and far future in electronics focus on the quest for new materials and novel device concepts to achieve low energy consumption, increased reliability and high device density. These can be obtained by designing active elements and interconnects whose operating principle is not (only) based on the electron charge but on the spin degree of freedom of the electron. The nanoscopic size of the materials calls for atomistic and parameter free (ab initio) simulations, which have proven to be crucial in achieving the necessary accuracy and predictive power. Materials which present a coupling between ferroelectricity and magnetism, i.e. magnetoelectric (ME) multiferroics, have been proposed as fundamental building blocks for spintronic devices. However ferroelectricity and magnetism are often exclusive or weakly coupled in bulk. In this talk, we will discuss how superlattices of perovskites can be designed from first principles to achieve strongly coupled ME and, hence, achieve control the weak magnetization via an electric field. Most important, advanced epitaxial techniques allow one to actually grow such magnetoelectric superlattices. Another route to optimize spintronic devices is to exploit the unique electronic and transport properties of Carbon-based nanomaterials. The latter present spin diffusion lengths up to 100 μm and high electron velocity. However, a large spin diffusion length comes at the price of small Spin Orbit coupling, which limits the possibility of manipulating electrons via an external applied field. Further, to achieve graphene-based devices one also needs to open its vanishing electronic gap. We use first principle techniques to show that placing graphene on a ME substrate can overcome these limitations by inducing magnetism and opening an electronic band-gap in the hybrid organic-multiferroic material. Z.Z. acknowledges EC support under the Marie-Curie IEF (PIEF-Ga-2011-300036), computational resources from the

  12. The memory effect of magnetoelectric coupling in FeGaB/NiTi/PMN-PT multiferroic heterostructure

    Science.gov (United States)

    Zhou, Ziyao; Zhao, Shishun; Gao, Yuan; Wang, Xinjun; Nan, Tianxiang; Sun, Nian X.; Yang, Xi; Liu, Ming

    2016-02-01

    Magnetoelectric coupling effect has provided a power efficient approach in controlling the magnetic properties of ferromagnetic materials. However, one remaining issue of ferromagnetic/ferroelectric magnetoelectric bilayer composite is that the induced effective anisotropy disappears with the removal of the electric field. The introducing of the shape memory alloys may prevent such problem by taking the advantage of its shape memory effect. Additionally, the shape memory alloy can also “store” the magnetoelectric coupling before heat release, which introduces more functionality to the system. In this paper, we study a FeGaB/NiTi/PMN-PT multiferroic heterostructure, which can be operating in different states with electric field and temperature manipulation. Such phenomenon is promising for tunable multiferroic devices with multi-functionalities.

  13. Robustness of magnetic and electric domains against charge carrier doping in multiferroic hexagonal ErMnO3

    Science.gov (United States)

    Hassanpour, E.; Wegmayr, V.; Schaab, J.; Yan, Z.; Bourret, E.; Lottermoser, Th; Fiebig, M.; Meier, D.

    2016-04-01

    We investigate the effect of chemical doping on the electric and magnetic domain pattern in multiferroic hexagonal ErMnO3. Hole- and electron doping are achieved through the growth of Er1‑x Ca x MnO3 and Er1‑x Zr x MnO3 single crystals, which allows for a controlled introduction of divalent and tetravalent ions, respectively. Using conductance measurements, piezoresponse force microscopy and nonlinear optics we study doping-related variations in the electronic transport and image the corrsponding ferroelectric and antiferromagnetic domains. We find that moderate doping levels allow for adjusting the electronic conduction properties of ErMnO3 without destroying its characteristic domain patterns. Our findings demonstrate the feasibility of chemical doping for non-perturbative property-engineering of intrinsic domain states in this important class of multiferroics.

  14. Stabilization of weak ferromagnetism by strong magnetic response to epitaxial strain in multiferroic BiFeO3

    International Nuclear Information System (INIS)

    Multiferroic BiFeO3 exhibits excellent magnetoelectric coupling critical for magnetic information processing with minimal power consumption. Thus, the degenerate nature of the easy spin axis in the (111) plane presents roadblocks for real world applications. Here, we explore the stabilization and switchability of the weak ferromagnetic moments under applied epitaxial strain using a combination of first-principles calculations and group-theoretic analyses. We demonstrate that the antiferromagnetic moment vector can be stabilized along unique crystallographic directions ([110] and [-110]) under compressive and tensile strains. A direct coupling between the anisotropic antiferrodistortive rotations and Dzyaloshinskii-Moria interactions drives the stabilization of weak ferromagnetism. Furthermore, energetically competing C- and G-type magnetic orderings are observed at high compressive strains, suggesting that it may be possible to switch the weak ferromagnetism on and off under application of strain. These findings emphasize the importance of strain and antiferrodistortive rotations as routes to enhancing induced weak ferromagnetism in multiferroic oxides

  15. First-principles approach to investigate toroidal property of magnetoelectric multiferroic GaFeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Nie, Yung-mau, E-mail: ymnie@ncnu.edu.tw [Department of Applied Materials and Optoelectronic Engineering, National Chi Nan University (NCNU), Nantou County 54561, Taiwan (China)

    2016-01-14

    A first-principles approach incorporating the concept of toroidal moments as a measure of the spin vortex is proposed and applied to simulate the toroidization of magnetoelectric multiferroic GaFeO{sub 3}. The nature of space-inversion and time-reversal violations of ferrotoroidics is reproduced in the simulated magnetic structure of GaFeO{sub 3}. For undoped GaFeO{sub 3}, a toroidal moment of −22.38 μ{sub B} Å per unit cell was obtained, which is the best theoretical estimate till date. Guided by the spin vortex free-energy minimization perturbed by an externally applied field, it was discovered that the minority spin markedly biases the whole toroidization. In summary, this approach not only calculates the toroidal moment but provides a way to understand the toroidal nature of magnetoelectric multiferroics.

  16. Magnetoelectric relaxor and reentrant behaviours in multiferroic Pb(Fe2/3W1/3)O3 crystal

    OpenAIRE

    Ling Chen; Bokov, Alexei A.; Weimin Zhu; Hua Wu; Jian Zhuang; Nan Zhang; Tailor, Hamel N.; Wei Ren; Zuo-Guang Ye

    2016-01-01

    Significant quenched disorder in crystal structure can break ferroic (magnetic or electric) long-range order, resulting in the development of ferroic glassy states at low temperatures such as magnetic spin glasses, electric dipolar glasses, relaxor ferroelectrics, etc. These states have been widely studied due to novel physical phenomena they reveal. Much less known are the effects of quenched disorder in multiferroics, i.e. the materials where magnetic and electric correlations coexist. Here...

  17. Impact of the various spin and orbital ordering processes on multiferroic properties of orthovanadate DyVO3

    OpenAIRE

    Q. Zhang; Singh, K.; Simon, C; Tung, L. D.; Balakrishnan, G.; Hardy, V.

    2012-01-01

    The orthovanadate DyVO3 crystal, known to exhibit multiple structural, spin and orbital ordering transitions, is presently investigated on the basis of magnetization, heat capacity, resistivity, dielectric and polarization measurements. Our main result is experimental evidence for the existence of multiferroicity below a high TC of 108 K over a wide temperature range including different spin-orbital ordered states. The onset of ferroelectricity is found to coincide with the antiferromagnetic ...

  18. James C. McGroddy Prize for New Materials Talk: What is new in multiferroicity?: Mott ferroelectrics!

    Science.gov (United States)

    Cheong, Sang-Wook

    2010-03-01

    Multiferroicity is an old topic. For example, linear magnetoelectric effect in materials such as Cr2O3 with broken time reversal and space inversion symmetry has been known since 1960's. However, giant cross-coupling effects such as flipping polarization or enormous change of dielectric constant by applied magnetic fields have been recently observed in systems such as Tb(Dy)MnO3 and Tb(Dy)Mn2O5 [1-3]. The important ingredient for these giant magnetoelectric effects turns out to be associated with the presence of non-zero d electrons and their mutual interactions, leading to the Mott-insulator-type charge gap, magnetism, and collective phase transitions. Particularly, the collective nature of simultaneous magnetic-ferroelectric phase transitions results in the giant magnetoelectric effects. In addition, fascinating charge transport properties such as a switchable photovoltaic effect and characteristic conduction properties at domain walls stem from the (carrier-doped) Mott insulating nature of compounds such as BiFeO3 and hexagonal YMnO3 [4,5]. [4pt] [1] Kimura, T. et al. Magnetic control of ferroelectric polarization. Nature 426, 55--58 (2003).[0pt] [2] Hur, N. et al. Electric polarization reversal and memory in a multiferroic material induced by magnetic fields. Nature 429, 392--395 (2004).[0pt] [3] Cheong, S.-W. & Mostovoy, M. Multiferroics: a magnetic twist for ferroelectricity. Nature Mater. 6, 13--20 (2007).[0pt] [4] Seidel, J. et al. Conduction at domain walls in oxide multiferroics. Nature Mater. 8, 229--234 (2009).[0pt] [5] Choi, T., Lee, S., Choi, Y.J., Kiryukhin, V. & Cheong, S.-W. Switchable ferroelectric diode and photovoltaic effect in BiFeO3. Science 324, 63--66 (2009)

  19. Investigations of surface structural, dynamical, and magnetic properties of systems exhibiting multiferroicity, and topological phases by helium scattering spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    El-Batanouny, Maged

    2015-08-03

    We propose to investigate the surface structural, dynamics and magnetic properties of the novel class of topological insulator crystals, as well as crystals that exhibit multiferroicity, magnetoelectricity and thermoelectricity. Topological insulators (TIs) are a new class of insulators in which a bulk gap for electronic excitations is generated because of the strong spin-orbit coupling inherent to these systems. These materials are distinguished from ordinary insulators by the presence of gapless metallic surface states, resembling chiral edge modes in quantum Hall systems, but with unconventional spin textures. These exotic metallic states are formed by topological conditions that also render the electrons travelling on such surfaces insensitive to scattering by impurities. The electronic quasi-particles populating the topological surface state are Dirac fermions; they have a linear dispersion and thus are massless just like photons. We propose to investigate the interaction of these massless Dirac fermions with the massive lattice in the newly discovered crystals, Bi2Se3, Bi2Te3 and Sb2Te3. We shall use inelastic helium beam scattering from surfaces to search for related signatures in surface phonon dispersions mappings that cover the entire surface Brillouin zone of these materials. Our recent investigations of the (001) surface of the multiferroic crystals (Li/Na)Cu2O2 revealed an anomalous surface structural behavior where surface Cu$^{2+}$ row rise above the surface plane as the crystal was cooled. Subsequent worming revealed the onset of a thermally activated incommensurate surface phase, driven by the elevated rows. We are currently investigating the structure of the magnetic phases in these quasi-one-dimensional magnetic rows. Multiferroics are excellent candidates for large magnetoelectric response. We propose to extend this investigation to the class of delafossites which are also multiferroics and have been investigated as good candidates for

  20. Structure, synthesis and multiferroic nature of BiFeO3 and 0.9BiFeO3–0.1BaTiO3: An overview

    Indian Academy of Sciences (India)

    Dhananjai Pandey; Anar Singh

    2009-06-01

    A brief review of the crystal structure and multiferroic nature of pure BiFeO3 and 0.9BiFeO3–0.1BaTiO3 (BF–0.1BT) is presented. An atomic level evidence for magnetoelectric coupling of intrinsic multiferroic origin in BF–0.1BT is presented.

  1. Symmetries and multiferroic properties of novel room-temperature magnetoelectrics: Lead iron tantalate – lead zirconate titanate (PFT/PZT

    Directory of Open Access Journals (Sweden)

    Dilsom A. Sanchez

    2011-12-01

    Full Text Available Mixing 60-70% lead zirconate titanate with 40-30% lead iron tantalate produces a single-phase, low-loss, room-temperature multiferroic with magnetoelectric coupling: (PbZr0.53Ti0.47O3 (1-x- (PbFe0.5Ta0.5O3x. The present study combines x-ray scattering, magnetic and polarization hysteresis in both phases, plus a second-order dielectric divergence (to epsilon = 6000 at 475 K for 0.4 PFT; to 4000 at 520 K for 0.3 PFT for an unambiguous assignment as a C2v-C4v (Pmm2-P4mm transition. The material exhibits square saturated magnetic hysteresis loops with 0.1 emu/g at 295 K and saturation polarization Pr = 25 μC/cm2, which actually increases (to 40 μC/cm2 in the high-T tetragonal phase, representing an exciting new room temperature oxide multiferroic to compete with BiFeO3. Additional transitions at high temperatures (cubic at T>1300 K and low temperatures (rhombohedral or monoclinic at T<250 K are found. These are the lowest-loss room-temperature multiferroics known, which is a great advantage for magnetoelectric devices.

  2. Structural transformation and multiferroic properties of Ba-Mn co-doped BiFeO3

    Science.gov (United States)

    Rout, Jyoshna; Choudhary, R. N. P.

    2016-01-01

    Pure BiFeO3 and Bi1-xBaxFe1-xMnxO3 (x = 0.10, 0.20) fine ceramics were synthesized using mechano-synthesis route. The influence of co-doping (Ba-Mn) on structural and multiferroic properties of BiFeO3 has been studied in different experimental conditions. X-ray diffraction patterns, Rietveld structural refinement of XRD patterns and Fourier transform infrared (FTIR) spectra reveal the structural transition from rhombohedral (R3c) to the biphasic structure (R3c + P4mm) on co-doping. The co-doping improves surface morphology and also reduces the particle size. The room temperature M-H loops of all samples showed antiferromagnetic/weak ferromagnetic behavior. Magnetoelectric coupling coefficient determination is carried out to reveal extent of intimate interaction between electric and magnetic dipoles interaction in the samples. Room temperature occurrence of ferromagnetism, ferroelectricity and magnetoelectric effect supports the observation of multiferroism and magnetoelectric coupling in BiFeO3. Thus, co-doping at Bi- and Fe-sites of BiFeO3 can improve multiferroic properties of BiFeO3 for various applications.

  3. Optical Diode Effect at Spin-Wave Excitations of the Room-Temperature Multiferroic BiFeO3

    Science.gov (United States)

    Kézsmárki, I.; Nagel, U.; Bordács, S.; Fishman, R. S.; Lee, J. H.; Yi, Hee Taek; Cheong, S.-W.; Rõõm, T.

    2015-09-01

    Multiferroics permit the magnetic control of the electric polarization and the electric control of the magnetization. These static magnetoelectric (ME) effects are of enormous interest: The ability to read and write a magnetic state current-free by an electric voltage would provide a huge technological advantage. Dynamic or optical ME effects are equally interesting, because they give rise to unidirectional light propagation as recently observed in low-temperature multiferroics. This phenomenon, if realized at room temperature, would allow the development of optical diodes which transmit unpolarized light in one, but not in the opposite, direction. Here, we report strong unidirectional transmission in the room-temperature multiferroic BiFeO3 over the gigahertz-terahertz frequency range. The supporting theory attributes the observed unidirectional transmission to the spin-current-driven dynamic ME effect. These findings are an important step toward the realization of optical diodes, supplemented by the ability to switch the transmission direction with a magnetic or electric field.

  4. Optical Diode Effect at Spin-Wave Excitations of the Room-Temperature Multiferroic BiFeO_{3}.

    Science.gov (United States)

    Kézsmárki, I; Nagel, U; Bordács, S; Fishman, R S; Lee, J H; Yi, Hee Taek; Cheong, S-W; Rõõm, T

    2015-09-18

    Multiferroics permit the magnetic control of the electric polarization and the electric control of the magnetization. These static magnetoelectric (ME) effects are of enormous interest: The ability to read and write a magnetic state current-free by an electric voltage would provide a huge technological advantage. Dynamic or optical ME effects are equally interesting, because they give rise to unidirectional light propagation as recently observed in low-temperature multiferroics. This phenomenon, if realized at room temperature, would allow the development of optical diodes which transmit unpolarized light in one, but not in the opposite, direction. Here, we report strong unidirectional transmission in the room-temperature multiferroic BiFeO_{3} over the gigahertz-terahertz frequency range. The supporting theory attributes the observed unidirectional transmission to the spin-current-driven dynamic ME effect. These findings are an important step toward the realization of optical diodes, supplemented by the ability to switch the transmission direction with a magnetic or electric field. PMID:26431014

  5. Impact of the various spin- and orbital-ordering processes on the multiferroic properties of orthovanadate DyVO3

    Science.gov (United States)

    Zhang, Q.; Singh, K.; Simon, C.; Tung, L. D.; Balakrishnan, G.; Hardy, V.

    2014-07-01

    The orthovanadate DyVO3 crystal, known to exhibit multiple structural, spin-, and orbital-ordering transitions, is presently investigated on the basis of magnetization, heat capacity, resistivity, dielectric, and polarization measurements. Our main result is experimental evidence for the existence of multiferroicity below a high TC of 108 K over a wide temperature range including different spin-orbital-ordered states. The onset of ferroelectricity is found to coincide with the antiferromagnetic C-type spin-ordering transition taking place at 108 K, which indicates that DyVO3 belongs to type-II multiferroics exhibiting a coupling between magnetism and ferroelectricity. Some anomalies detected on the temperature dependence of electric polarization are discussed with respect to the nature of the spin-orbital-ordered states of the V sublattice and the degree of spin alignment in the Dy sublattice. The orthovanadates RVO3 (R= rare earth or Y) form an important new category for searching for high-TC multiferroics.

  6. Generation of localized strain in a thin film piezoelectric to control individual magnetoelectric heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Jizhai; Liang, Cheng-Yen; Sepulveda, Abdon; Carman, Gregory P.; Lynch, Christopher S., E-mail: cslynch@seas.ucla.edu [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095 (United States); Paisley, Elizabeth A.; Ihlefeld, Jon F. [Electronic, Optical, and Nano Materials Department, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    2015-08-31

    Experimental results demonstrate the ability of a surface electrode pattern to produce sufficient in-plane strain in a PbZr{sub 0.52}Ti{sub 0.48}O{sub 3} (PZT) thin film clamped by a Si substrate to control magnetism in a 1000 nm diameter Ni ring. The electrode pattern and the Ni ring/PZT thin film heterostructure were designed using a finite element based micromagnetics code. The magnetoelectric heterostructures were fabricated on the PZT film using e-beam lithography and characterized using magnetic force microscopy. Application of voltage to the electrodes moved one of the “onion” state domain walls. This method enables the development of complex architectures incorporating strain-mediated multiferroic devices.

  7. Magneto-capacitance effects in epitaxial TbMn2O5 thin films

    Science.gov (United States)

    Song, Jong Hyun; Kang, Sun Hee; Kim, Ill Won; Jeong, Yoon Hee; Koo, Tae Yeong

    2012-11-01

    Thin films of TbMn2O5 (TMO) were grown on Nb-doped TiO2 (110) substrates by using pulsed laser deposition to investigate the effects of substrate-induced strains on the multiferroic properties observed in the bulk phase. The epitaxial qualities of the films were confirmed by using X-ray azimuthal angle scans of the TMO (201) and the TiO2 (111) reflections. TMO films were magnetically ordered at temperatures below T N ≈ 43 K, consistent with the value observed in the bulk. A maximum negative magneto-capacitance effect of about 10% at 8 T was detected near 16 K, where the dielectric constant changed rapidly with a step-like anomaly. Magnetization-induced ferroelectric phases in the epitaxial thin films appear to become destabilized at temperatures below T N due to substrate-induced tensile strains causing a weakening of the magnetic exchange interactions.

  8. Spin-lattice coupling in multiferroic Pb(Fe1/2Nb1/2)O3 thin films

    OpenAIRE

    Peng, W.; Lemée, N.; Karkut, M.; Dkhil, B.; Shvartsman, V. V.; Borisov, P.; Kleemann, W.; Holc, J.; Kosec, M.; Blinc, R.

    2009-01-01

    We have made magnetization and x-ray diffraction measurements on an epitaxial Pb(Fe1/2Nb1/2)O3 200 nm film. From the temperature dependence of the out-of-plane lattice parameter we can assign a Burns' temperature at Td ~ 640 K, a temperature at T* ~ 510 K, related to the appearance of static polar nanoregions, and an anomaly occurring at 200 K. The latter is precisely the N\\'eel temperature TN determined from magnetization and points to spin-lattice coupling at TN ~ 200 K. We also observe "we...

  9. Thin films

    International Nuclear Information System (INIS)

    This volume is a compilation of papers presented at the 1990 Spring Meeting of the Materials Research Society in a symposium entitled Thin Films: Stresses and Mechanical Properties II. As indicated by the title, the symposium was the second in a series, the first of which was held at the Fall Meeting in 1988. The importance of thin film mechanical properties is now recognized to the extent that basic characterization techniques such as microindentation and thin film stress measurement are performed routinely, and new characterization techniques are being developed on a daily basis. Many of the papers in the symposium dealt with the developments in these characterization methods and their application to a broad spectrum of materials such as compositionally modulated structures, ion implanted materials, optical coatings, and the numerous metals, ceramics and organics used in semiconductor device manufacture

  10. Thin Places

    OpenAIRE

    Lockwood, Sandra Elizabeth

    2013-01-01

    This inquiry into the three great quests of the twentieth century–the South Pole, Mount Everest, and the Moon–examines our motivations to venture into these sublime, yet life-taking places. The Thin Place was once the destination of the religious pilgrim seeking transcendence in an extreme environment. In our age, the Thin Place quest has morphed into a challenge to evolve beyond the confines of our own physiology; through human ingenuity and invention, we reach places not meant to accommod...

  11. Thin book

    DEFF Research Database (Denmark)

    En lille bog om teater og organisationer, med bidrag fra 19 teoretikere og praktikere, der deltog i en "Thin Book Summit" i Danmark i 2005. Bogen bidrager med en state-of-the-art antologi om forskellige former for samarbejde imellem teater og organisationer. Bogen fokuserer både på muligheder og...

  12. Thin Films

    Czech Academy of Sciences Publication Activity Database

    Šolcová, Olga

    Maribor: Univerza v Mariboru, 2013. [Nanofuture. Maribor (SI), 03.02.2013-07.02.2013] R&D Projects: GA TA ČR TA01020804 Institutional support: RVO:67985858 Keywords : sol-gel methods * thin films * nannomaterials Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  13. Multiferroic nanomagnetic logic: Hybrid spintronics-straintronic paradigm for ultra-low energy computing

    Science.gov (United States)

    Salehi Fashami, Mohammad

    Excessive energy dissipation in CMOS devices during switching is the primary threat to continued downscaling of computing devices in accordance with Moore's law. In the quest for alternatives to traditional transistor based electronics, nanomagnet-based computing [1, 2] is emerging as an attractive alternative since: (i) nanomagnets are intrinsically more energy-efficient than transistors due to the correlated switching of spins [3], and (ii) unlike transistors, magnets have no leakage and hence have no standby power dissipation. However, large energy dissipation in the clocking circuit appears to be a barrier to the realization of ultra low power logic devices with such nanomagnets. To alleviate this issue, we propose the use of a hybrid spintronics-straintronics or straintronic nanomagnetic logic (SML) paradigm. This uses a piezoelectric layer elastically coupled to an elliptically shaped magnetostrictive nanomagnetic layer for both logic [4-6] and memory [7-8] and other information processing [9-10] applications that could potentially be 2-3 orders of magnitude more energy efficient than current CMOS based devices. This dissertation focuses on studying the feasibility, performance and reliability of such nanomagnetic logic circuits by simulating the nanoscale magnetization dynamics of dipole coupled nanomagnets clocked by stress. Specifically, the topics addressed are: 1. Theoretical study of multiferroic nanomagnetic arrays laid out in specific geometric patterns to implement a "logic wire" for unidirectional information propagation and a universal logic gate [4-6]. 2. Monte Carlo simulations of the magnetization trajectories in a simple system of dipole coupled nanomagnets and NAND gate described by the Landau-Lifshitz-Gilbert (LLG) equations simulated in the presence of random thermal noise to understand the dynamics switching error [11, 12] in such devices. 3. Arriving at a lower bound for energy dissipation as a function of switching error [13] for a

  14. Magnetoelastic coupling in multilayered ferroelectric/ferromagnetic thin films: A quantitative evaluation

    International Nuclear Information System (INIS)

    The electrical control of magnetization in a thin film, achieved by means of magnetoelastic coupling between a ferroelectric and a ferromagnetic layer represents an attractive way to implement magnetic information storage and processing within logical architectures known as Magnetic Quantum Cellular Automata (MQCA). Such systems have been addressed as multiferroics. We exploited cost-effective techniques to realize multi-layered multiferroic systems, such as sol-gel deposition and RF sputtering, introducing a specific technique to control the crystal structure and film roughness effect on the magnetic domain wall motion and reconfiguration, induced by magnetoelastic coupling, by evaluating the 2-dimensional statistical properties of enhanced MFM matrices. A RF sputtered 50-nm-thick Co layer on a Si/SiO2/Si3N4/Ti/Pt/PbTiO3/Pb(Zr0.53Ti0.47)O3 substrate was realized, exploiting two differently engineered PZT nano-crystalline structures and the conditions leading to a favorable compromise in order to realize functional devices were elucidated.

  15. Change in the magnetic structure of (Bi,SmFeO3 thin films at the morphotropic phase boundary probed by neutron diffraction

    Directory of Open Access Journals (Sweden)

    Shingo Maruyama

    2014-11-01

    Full Text Available We report on the evolution of the magnetic structure of BiFeO3 thin films grown on SrTiO3 substrates as a function of Sm doping. We determined the magnetic structure using neutron diffraction. We found that as Sm increases, the magnetic structure evolves from a cycloid to a G-type antiferromagnet at the morphotropic phase boundary, where there is a large piezoelectric response due to an electric-field induced structural transition. The occurrence of the magnetic structural transition at the morphotropic phase boundary offers another route towards room temperature multiferroic devices.

  16. Cr3+ NMR for Multiferroic Chromium spinel ZnCr2Se4

    Science.gov (United States)

    Park, Sejun; Kwon, Sangil; Lee, Soonchil; Khim, Seunghyun; Bhoi, Dilip Kumar; Kim, Kee Hoon

    Multiferroic systems including ZnCr2Se4, the chromium spinel with helical spin structure, have been in huge interest for decades due to its physical variety and applicability. In the temperature range between 21K and 80K, this material shows negative thermal expansion. Due to the bond frustration, the spins of the chromium ions order helically below the transition temperature, 21K, though the exchange constant tends to make a ferro-order. The anomalous 1storder-like magnetic transition is yet clarified and still an interesting topic. To probe microscopic origin of these features, we measured zero-field NMR of Cr3+ ions having nuclear spin 3/2. Six peaks were observed revealing Nuclear Quadrupole Resonance(NQR) and anisotropic hyperfine field at chromium sites. The NQR spectrum reveals that the structure is highly distorted below the magnetic transition temperature where the normal Jahn-Teller distortion is absent. Temperature dependence of the spectrum is also measured to obtain the magnetization as a function of temperature.

  17. Modified Heisenberg model for the zig-zag structure in multiferroic RMn2O5

    International Nuclear Information System (INIS)

    The class of RMn2O5 (R = Ho, Tb, Y, Eu) compounds offers multiferroic properties where the refined magnetic zig-zag order breaks the inversion symmetry. Varying the temperature, the system undergoes a magnetic and a subsequent ferroelectric phase transition where the ferroelectricity is magnetically induced. We propose a modified anisotropic Heisenberg model that can be used as a tractable analytical model studying the properties of those antiferromagnetic zig-zag spin chains. Based on a finite temperature Green's function method, it is shown that the polarization is induced solely by different exchange couplings of the two different Mn4+ and Mn3+ magnetic ions. We calculate the excitation energy of the spin system for finite temperatures, which for its part determines the temperature dependent magnetization and polarization. The ferroelectric phase transition is manifested as a kink in the excitation energy. The variation of the polarization by an external magnetic field depends strongly on the direction of that field. Whereas, the polarization in b-direction increases with an external magnetic field as well in b-direction it can be switched for strong fields in a-direction. The results based on that modified Heisenberg model are in qualitative agreement with experimental data

  18. Effects of size and oxygen annealing on the multiferroic behavior of bismuth ferrite nanoparticles

    International Nuclear Information System (INIS)

    We have compared the multiferroic behavior in different-sized BiFeO3 nanoparticles (11–29 nm) prepared by a solution evaporation method. The effects of oxygen vacancies on the behavior of phase pure BiFeO3 have been studied for particles prepared under two different annealing environments, air and oxygen. We find that BiFeO3 nanoparticles show weak ferromagnetism at room temperature which increases with decreasing particle size. However, the effects are determined not to be related to the presence of more oxygen vacancies, since oxygen annealing increases the magnetic moment in this system. In dielectric studies, we observe clear evidence for magnetoelectric coupling with the imaginary part of dielectric constant exhibiting a clear anomaly around the magnetic transition temperature (T ∼ 560 K). In high temperature resistivity measurements insulating and activated resistivity behavior is observed with the activation energies being lower for T N. The increased ferromagnetism in smaller particles is explained in terms of suppression of the antiferromagnetic spin spiral whereas oxygen annealing actually leads in our case to an improvement of the crystallinity.

  19. Effects of size and oxygen annealing on the multiferroic behavior of bismuth ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Manzoor, Alina; Hasanain, S. K., E-mail: skhasanain@qau.edu.pk; Mumtaz, A. [Quaid-I-Azam University, Physics Department (Pakistan); Bertino, M. F.; Franzel, L. [Virginia Commonwealth University, Physics Department (United States)

    2012-12-15

    We have compared the multiferroic behavior in different-sized BiFeO{sub 3} nanoparticles (11-29 nm) prepared by a solution evaporation method. The effects of oxygen vacancies on the behavior of phase pure BiFeO{sub 3} have been studied for particles prepared under two different annealing environments, air and oxygen. We find that BiFeO{sub 3} nanoparticles show weak ferromagnetism at room temperature which increases with decreasing particle size. However, the effects are determined not to be related to the presence of more oxygen vacancies, since oxygen annealing increases the magnetic moment in this system. In dielectric studies, we observe clear evidence for magnetoelectric coupling with the imaginary part of dielectric constant exhibiting a clear anomaly around the magnetic transition temperature (T {approx} 560 K). In high temperature resistivity measurements insulating and activated resistivity behavior is observed with the activation energies being lower for T < T{sub N}. The increased ferromagnetism in smaller particles is explained in terms of suppression of the antiferromagnetic spin spiral whereas oxygen annealing actually leads in our case to an improvement of the crystallinity.

  20. Defect driven multiferroicity in Gd doped BiFeO3 at room temperature

    International Nuclear Information System (INIS)

    This paper reports that defect driven magnetism can be obtained at room temperature by optimizing metal ion concentration in bismuth ferrite (BFO) following our novel slow step solid state sintering route. We observed a clean signature of enhanced multiferroic behavior in Gd doped bismuth ferrite (Gd-BFO) bulk ceramics at room temperature (RT). Bismuth rich iron deficient Gd-BFO ceramics were prepared by solid state route through slow step sintering schedule at 850 oC. At particular composition, (Bi1.2Gd0.1Fe0.8O3), this materials completely transform from rhombohedral R3c to orthorhombic Pn21a space group. We emphasized that excess bismuth is expected to act as point defects and occupy interstitials positions, which in turn interact by oxygen vacancies. These defects are likely to promote defect driven ferromagnetism in BFO system. Incorporation of Gd in presence of excess bismuth in BFO enhanced both spin and electric polarization at room temperature. We also infer that Gd substitution in BFO is likely to suppress spiral spin modulation, which also favors ferromagnetism in Gd-BFO.

  1. Inelastic Neutron Scattering on Multiferroics NdFe3(BO3)4

    Science.gov (United States)

    Hayashida, Shohei; Soda, Minoru; Itoh, Shinichi; Yokoo, Tetsuya; Ohgushi, Kenya; Kawana, Daichi; Masuda, Takatsugu

    Inelastic neutron scattering experiment is performed on single crystals of multiferroics NdFe3(11BO3)4 to explore the magnetic excitations. Fe-centered dispersive excitation with the band width of 5 meV is observed along the crystallographic c∗ direction and that of 3 meV is along the a∗ direction. The energy gap of 0.57 meV due to an axial-type anisotropy is ob- served at the AF zone center. The energy of Nd-centered flat excitation is 1 meV. Furthermore, anticrossing of the Fe- and Nd-centered excitations is observed, meaning the existence of the f -d coupling, i.e., the interaction between the Nd3+ and Fe3+ moments. Spin-wave analysis on the observed neutron spectrum revealed the underlying magnetic Hamiltonian in NdFe3(11BO3)4. Discussion on the axial-type anisotropy in the ab - plane based on the magnetic model leads to the conclusion that the anisotropy of the Nd3+ ion plays a main role in the determination of the structures of both magnetic moment and electric polarization in NdFe3(BO3)4.

  2. Terahertz spectroscopy of multiferroic EuFe{sub 3}(BO{sub 3}){sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Boldyrev, K.N., E-mail: kn.boldyrev@gmail.com [Institute of Spectroscopy, RAS, Troitsk, Moscow region, 142190 (Russian Federation); Stanislavchuk, T.N. [Department of Physics, New Jersey Institute of Technology, Newark, NJ 07102 (United States); Klimin, S.A.; Popova, M.N. [Institute of Spectroscopy, RAS, Troitsk, Moscow region, 142190 (Russian Federation); Bezmaternykh, L.N. [Kirensky Institute of Physics, Siberian Branch of RAS, Krasnoyarsk, 660036 (Russian Federation)

    2012-07-30

    The terahertz spectra of a rare-earth iron borate with the huntite structure are obtained for the first time. We study the low-temperature (4.0–90 K) α-polarized transmittance spectra of the EuFe{sub 3}(BO{sub 3}){sub 4} single crystal in the region 0.9–6.0 THz. Pronounced shifts of phonon frequencies and appearance of new phonon modes at the temperature T{sub S}=58 K of the R32→P3{sub 1}21 structural phase transition are observed. Additional shifts of phonon frequencies occur at the temperature T{sub N}=34 K of the magnetic ordering of the Fe subsystem, thus evidencing the spin–phonon coupling in this multiferroic material. -- Highlights: ► Terahertz spectroscopy was applied to study phase transitions of RFe{sub 3}(BO{sub 3}){sub 4} compounds. ► Phase transition at T{sub S} is observed by shifts of phonons and appearance of new ones. ► Peculiarities at T{sub N} in the phonon ω(T) curves evidence the spin–phonon coupling. ► Spin–phonon coupling is connected with atomic displacements in internal magnetic field.

  3. Giant Controllable Magnetization Changes Induced by Structural Phase Transitions in a Metamagnetic Artificial Multiferroic.

    Science.gov (United States)

    Bennett, S P; Wong, A T; Glavic, A; Herklotz, A; Urban, C; Valmianski, I; Biegalski, M D; Christen, H M; Ward, T Z; Lauter, V

    2016-01-01

    The realization of a controllable metamagnetic transition from AFM to FM ordering would open the door to a plethora of new spintronics based devices that, rather than reorienting spins in a ferromagnet, harness direct control of a materials intrinsic magnetic ordering. In this study FeRh films with drastically reduced transition temperatures and a large magneto-thermal hysteresis were produced for magnetocaloric and spintronics applications. Remarkably, giant controllable magnetization changes (measured to be as high has ~25%) are realized by manipulating the strain transfer from the external lattice when subjected to two structural phase transitions of BaTiO3 (001) single crystal substrate. These magnetization changes are the largest seen to date to be controllably induced in the FeRh system. Using polarized neutron reflectometry we reveal how just a slight in plane surface strain change at ~290C results in a massive magnetic transformation in the bottom half of the film clearly demonstrating a strong lattice-spin coupling in FeRh. By means of these substrate induced strain changes we show a way to reproducibly explore the effects of temperature and strain on the relative stabilities of the FM and AFM phases in multi-domain metamagnetic systems. This study also demonstrates for the first time the depth dependent nature of a controllable magnetic order using strain in an artificial multiferroic heterostructure. PMID:26940159

  4. Induced modifications in the properties of Sr doped BiFeO3 multiferroics

    Institute of Scientific and Technical Information of China (English)

    Tanvir Hussain; Saadat A. Siddiqi; Shahid Atiq; M.S. Awan

    2013-01-01

    Multiferroics exhibit unique combination of ferroic properties, simultaneously. For instance, in BiFeO3, magnetic and electric properties co-exist. In this work, BiFeO3 and Sr-doped BiFeO3 samples with general formula, Bi1 ? xSrxFeO3 (x ¼ 0.00, 0.05, 0.10, 0.20, and 0.30) were synthesized by sol-gel auto-combustion technique, in order to investigate these ferroic properties. The samples were confirmed to have perovskite type rhombohedral structure, characteristic of BiFeO3. A dilute phase of Bi2Fe4O9 was also found in all the Sr-doped samples. The micrographs of the palletized samples revealed that minutely doped Sr might not have any effect on the morphology of the samples. Frequency dependent dielectric measurements were carried out at room temperature for all the samples from 100 Hz to 1 MHz. The dielectric constant of un-doped sample at low frequency was 52 which decreased with increasing Sr doping. An enhancement of magnetic properties was observed with increasing the Sr contents. Pure BiFeO3 material was observed to have the least value of remanent magnetization. As the Sr2þ ions were doped in BiFeO3, its magnetization and remanence were increased to 0.867 emu/g and 0.175 emu/g, respectively, at x ¼ 0.30.

  5. Quantum Otto heat engine based on a multiferroic chain working substance

    International Nuclear Information System (INIS)

    We study a quantum Otto engine operating on the basis of a helical spin-1/2 multiferroic chain with strongly coupled magnetic and ferroelectric order parameters. The presence of a finite spin chirality in the working substance enables steering of the cycle by an external electric field that couples to the electric polarization. We observe a direct connection between the chirality, the entanglement and the efficiency of the engine. An electric-field dependent threshold temperature is identified, above which the pair correlations in the system, as quantified by the thermal entanglement, diminish. In contrast to the pair correlations, the collective many-body thermal entanglement is less sensitive to the electric field, and in the high temperature limit converges to a constant value. We also discuss the correlations between the threshold temperature of the pair entanglement, the spin chirality and the minimum of the fidelities in relation to the electric and magnetic fields. The efficiency of the quantum Otto cycle shows a saturation plateau with increasing electric field amplitude. (paper)

  6. Intrinsic Ferroelasticity and/or Multiferroicity in Two-Dimensional Phosphorene and Phosphorene Analogues.

    Science.gov (United States)

    Wu, Menghao; Zeng, Xiao Cheng

    2016-05-11

    Phosphorene and phosphorene analogues such as SnS and SnSe monolayers are promising nanoelectronic materials with desired bandgap, high carrier mobility, and anisotropic structures. Here, we show first-principles calculation evidence that these monolayers are potentially the long-sought two-dimensional (2D) materials that can combine electronic transistor characteristic with nonvolatile memory readable/writeable capability at ambient condition. Specifically, phosphorene is predicted to be a 2D intrinsic ferroelastic material with ultrahigh reversible strain, whereas SnS, SnSe, GeS, and GeSe monolayers are multiferroic with coupled ferroelectricity and ferroelasticity. Moreover, their low-switching barriers render room-temperature nonvolatile memory accessible, and their notable structural anisotropy enables ferroelastic or ferroelectric switching readily readable via electrical, thermal, optical, mechanical, or even spintronic detection upon the swapping of the zigzag and armchair direction. In addition, it is predicted that the GeS and GeSe monolayers as well as bulk SnS and SnSe can maintain their ferroelasticity and ferroelectricity (anti-ferroelectricity) beyond the room temperature, suggesting high potential for practical device application. PMID:27096689

  7. Giant Controllable Magnetization Changes Induced by Structural Phase Transitions in a Metamagnetic Artificial Multiferroic

    Science.gov (United States)

    Bennett, S. P.; Wong, A. T.; Glavic, A.; Herklotz, A.; Urban, C.; Valmianski, I.; Biegalski, M. D.; Christen, H. M.; Ward, T. Z.; Lauter, V.

    2016-03-01

    The realization of a controllable metamagnetic transition from AFM to FM ordering would open the door to a plethora of new spintronics based devices that, rather than reorienting spins in a ferromagnet, harness direct control of a materials intrinsic magnetic ordering. In this study FeRh films with drastically reduced transition temperatures and a large magneto-thermal hysteresis were produced for magnetocaloric and spintronics applications. Remarkably, giant controllable magnetization changes (measured to be as high has ~25%) are realized by manipulating the strain transfer from the external lattice when subjected to two structural phase transitions of BaTiO3 (001) single crystal substrate. These magnetization changes are the largest seen to date to be controllably induced in the FeRh system. Using polarized neutron reflectometry we reveal how just a slight in plane surface strain change at ~290C results in a massive magnetic transformation in the bottom half of the film clearly demonstrating a strong lattice-spin coupling in FeRh. By means of these substrate induced strain changes we show a way to reproducibly explore the effects of temperature and strain on the relative stabilities of the FM and AFM phases in multi-domain metamagnetic systems. This study also demonstrates for the first time the depth dependent nature of a controllable magnetic order using strain in an artificial multiferroic heterostructure.

  8. Synthesis, microstructure and properties of BiFeO{sub 3}-based multiferroic materials: A review

    Energy Technology Data Exchange (ETDEWEB)

    Bernardo, M. S.

    2014-02-01

    BiFeO{sub 3}-based materials are currently one of the most studied multiferroics due to their possible applications at room temperature. However, among the large number of published papers there is much controversy. For example, possibility of synthesizing a pure BiFeO{sub 3} phase is still source of discussion in literature. Not even the nature of the binary Bi{sub 2}O{sub 3}-Fe{sub 2}O{sub 3} diagram has been clarified yet. The difficulty in controlling the formation of parasite phases reaches the consolidation step. Accordingly, the sintering conditions must be carefully determined both to get dense materials and to avoid bismuth ferrite decomposition. However, the precise conditions to attain dense bismuth ferrite materials are frequently contradictory among different works. As a consequence, the reported properties habitually result opposed and highly irreproducible hampering the preparation of BiFeO{sub 3} materials suitable for practical applications. In this context, the purpose of the present review is to summarize the main researches regarding BiFeO{sub 3} synthesis, microstructure and properties in order to provide an easier understanding of these materials. (Author)

  9. Electric polarization observed in single crystals of multiferroic Lu2MnCoO6

    Science.gov (United States)

    Chikara, S.; Singleton, J.; Bowlan, J.; Yarotski, D. A.; Lee, N.; Choi, H. Y.; Choi, Y. J.; Zapf, V. S.

    2016-05-01

    We report electric polarization and magnetization measurements in single crystals of double perovskite Lu2Mn Co O6 using pulsed magnetic fields and optical second harmonic generation in dc magnetic fields. We observe well-resolved magnetic field-induced changes in the electric polarization in single crystals and thereby resolve the question about whether multiferroic behavior is intrinsic to these materials or is an extrinsic feature of polycrystals. We find electric polarization along the crystalline b axis, that is suppressed by applying a magnetic fields along the c axis, and advance a model for the origin of magnetoelectric coupling. We furthermore map the phase diagram using both capacitance and electric polarization to identify regions of ordering and regions of magnetoelectric hysteresis. This compound is a rare example of coupled hysteretic behavior in the magnetic and electric properties. The ferromagneticlike magnetic hysteresis loop that couples to hysteretic electric polarization can be attributed not to ordinary ferromagnetic domains, but to the rich physics of magnetic frustration of Ising-like spins in the axial next-nearest-neighbor interaction model.

  10. Synthesis, microstructure and properties of BiFeO3-based multiferroic materials: A review

    International Nuclear Information System (INIS)

    BiFeO3-based materials are currently one of the most studied multiferroics due to their possible applications at room temperature. However, among the large number of published papers there is much controversy. For example, possibility of synthesizing a pure BiFeO3 phase is still source of discussion in literature. Not even the nature of the binary Bi2O3-Fe2O3 diagram has been clarified yet. The difficulty in controlling the formation of parasite phases reaches the consolidation step. Accordingly, the sintering conditions must be carefully determined both to get dense materials and to avoid bismuth ferrite decomposition. However, the precise conditions to attain dense bismuth ferrite materials are frequently contradictory among different works. As a consequence, the reported properties habitually result opposed and highly irreproducible hampering the preparation of BiFeO3 materials suitable for practical applications. In this context, the purpose of the present review is to summarize the main researches regarding BiFeO3 synthesis, microstructure and properties in order to provide an easier understanding of these materials. (Author)

  11. Giant dielectric response and enhanced thermal stability of multiferroic BiFeO3

    International Nuclear Information System (INIS)

    Highlights: • We report a novel wet chemical route for facile and large-scale fabricate of BiFeO3. • Giant dielectric response was observed in BiFeO3 ceramics. • BiFeO3 nanoparticles, fabricated by the novel method, are thermally stable up to 900 °C. • This synthesis technique can be easily extended to many other functional material systems. - Abstract: A wet chemical synthesis technique for large-scale fabrication of multiferroic bismuth ferrite (BiFeO3) nanoparticles under ambient pressure is reported. The process employs bismuth nitride and potassium hexacyanoferrate as raw materials and involves easy control and simple operation steps. The single crystalline nature of BiFeO3 was confirmed by X-ray diffraction (XRD) and selected area electron diffraction pattern. This synthesis technique can be extended to many other material systems and it provides a general, simple and convenient route for large-scale fabrication of nanocomplex oxides. Our results revealed that the synthesized BiFeO3 ceramics exhibited giant dielectric constant (>104) and two dielectric relaxations. A Debye-like relaxation was found at relatively low temperature with activation energy of 0.25 eV, which was assigned to the carrier hopping process between Fe2+ and Fe3+ sites in BiFeO3. The grain boundary effect contributed to the relative high temperature dielectric relaxation

  12. Calcination temperature influenced multiferroic properties of Ca-doped BiFeO3 nanoparticles

    International Nuclear Information System (INIS)

    The influence of Ca-doping and particle size on structural, morphological and magnetic properties of BiFeO3 nanoparticles has been studied. A sol-gel method was employed for the synthesis of nanoparticles and their particle size was tailored by varying the calcination temperature. Structural analysis revealed a rhombohedral distortion induced by Ca-substitution. The broadening of diffraction peaks with decreasing calcination temperature was indicative of reduction in crystallite size. The morphological analysis revealed the formation of agglomerated nanoparticles having average particle size ranging from 10-15 and 50-55 nm for C4 and C6, respectively. The agglomeration is attributed to high surface energy of nanoparticles. Ferromagnetism has been displayed by all the synthesized nanoparticles. Enhancement of saturation magnetization with Ca-substitution is attributed to suppression of spin cycloid structure by the reduction in size, lattice distortion and creation of oxygen vacancies by the substitution of divalent ion at trivalent site. Further, this value increases as a function of decreasing particle size. Strong particle size effects on magnetic properties of the synthesized nanoparticles are owed to increasing surface to volume ratio. All these observations are indicative of strong dependence of multiferroism on particle size

  13. Specific heat and magnetocaloric effect in RMnO3 (R=Gd and Tb) multiferroics

    International Nuclear Information System (INIS)

    Multiferroic RMnO3 (R= Gd and Tb) samples were prepared through sol gel method. After characterizing the sample structurally, a systematic investigation of specific heat was performed over the temperature range 4-70 K under 0T, 2T and 5T magnetic fields to study the magnetocaloric effect. The samples are found to exhibit three transitions near 40 K, 25 K and below 10 K. The hump at 10 K broadens under magnetic fields of 2T and 5T, indicating the shift in entropy to higher temperature. The magnetocaloric effect (MCE) of the samples in terms of isothermal entropy change (ΔS) and adiabatic temperature change (ΔTad) was evaluated from these specific heat measurements under 2T and 5T magnetic fields. From the systematic analysis it has been observed that the samples can be used as magnetic refrigerant that induces an adiabatic cooling of about ΔTad ≈ 2.4 K on application of 5T magnetic fields in the temperature range 4-30 K

  14. Neutron diffraction study on the frustrated multiferroic TbMn1-xFexO3

    International Nuclear Information System (INIS)

    The improper ferroelectric ordering can be induced by a spiral magnetic ordering below 28K in TbMn03, which can be attributed to the inverse Dzyaloshinskii-Moriya interaction (spin current model). The investigation of the spiral ordering is extremely important for exploring possible new multiferroic materials. Electronic doping, such as Fe3+, on the 3d orbital is supposed to introduce stronger antiferromagnetic interaction, which may increases the transition temperature of spiral magnetic ordering and ferroelectric ordering. Whether will the spiral ordering still exist? Or how does the electronic doping effect the magnetic ordering? In our work, the neutron study shows that the long-range magnetic ordering of transitional metal ion spins is disturbed and no magnetic diffraction can be observed above 6K. In addition, the first-principle calculation shows the same results. Therefore, the spiral magnetic ordering is very sensitive to the electronic doping. In addition, the long range antiferromagnetic ordering is also quenched by a small amount of Fe3+ doping, which shows the complex exchange interaction in this system.

  15. Pressure-induced polar phases in relaxor multiferroic $PbFe_{0.5}Nb_{0.5}O_{3}$

    OpenAIRE

    Kozlenko, Denis; Kichanov, S. E.; E. V. Lukin; Dang, N. T.; Dubrovinsky, Leonid; Liermann, H.-P.; Morgenroth, W.; Kamynin, A. A.; Gridnev, S. A.; B. N. Savenko

    2014-01-01

    The structural, magnetic, and vibrational properties of PbFe0.5Nb0.5O3 relaxor multiferroic have been studied by means of x-ray, neutron powder diffraction, and Raman spectroscopy at pressures up to 30 GPa. Two successive structural phase transitions from the initial R3m polar phase to Cm and Pm monoclinic polar phases were observed at P = 5.5 and 8.5 GPa. Both transitions are associated with anomalies in pressure behavior of several stretching and bending modes of oxygen octahedra as well as...

  16. Low Temperature Magnetic Studies on PbFe0.5Nb0.5O3 Multiferroic

    OpenAIRE

    Matteppanavar, Shidaling; Angadi, Basavaraj; Rayaprol, Sudhindra

    2015-01-01

    The PbFe0.5Nb0.5O3 (PFN), a well-known A(B'1/2B"1/2)O3 type multiferroic was successfully synthesized in single phase by a single step solid state reaction method. The single phase PFN was characterized through XRD, microstructure through SEM, and magnetic studies were carried out through temperature dependent vibrating sample magnetometer (VSM) and neutron diffraction (ND) measurements. PFN exhibits a cusp at around 150 K in the temperature dependent magnetic susceptibility corresponding to ...

  17. Tuning ferroic states in La doped BiFeO3-PbTiO3 displacive multiferroic compounds

    International Nuclear Information System (INIS)

    In this manuscript, X-ray and high-resolution neutron powder diffraction investigations, associated with Rietveld refinements, magnetic hysteresis curves and a modeling of electron-density distributions around the ions, are used to describe the driving forces responsible for tuning the ferroic states in La doped (0.6)BiFeO3-(0.4)PbTiO3 compositions. The intrinsic relations between the ferroic orders and the structural arrangements (angles, distances and electron-density distributions around the ions) are revealed, helping in the understanding of some aspects comprising the ferroic properties of perovskite-based displacive multiferroic compounds.

  18. Pressure effects on magnetic ground states in cobalt doped multiferroic Mn$_{1-x}$Co$_{x}$WO$_4$

    OpenAIRE

    Wang, Jinchen; Ye, Feng; Chi, Songxue; Fernandez-Baca, Jaime A.; Cao, Huibo; Tian, Wei; Gooch, M.; Poudel, N.; Wang, Yaqi; Lorenz, Bernd; Chu, C. W.

    2016-01-01

    Using ambient pressure x-ray and high pressure neutron diffraction, we studied the pressure effect on structural and magnetic properties of multiferroic Mn$_{1-x}$Co$_x$WO$_4$ single crystals ($x=0, 0.05, 0.135$ and $0.17$), and compared it with the effects of doping. Both Co doping and pressure stretch the Mn-Mn chain along the $c$~direction. At high doping level ($x=0.135$ and $0.17$), pressure and Co doping drive the system in a similar way and induce a spin-flop transition for the $x=0.13...

  19. Magnetoelectric effect in Cr2O3 thin films

    Science.gov (United States)

    He, Xi; Wang, Yi; Sahoo, Sarbeswar; Binek, Christian

    2008-03-01

    Magnetoelectric materials experienced a recent revival as promising components of novel spintronic devices [1, 2, 3]. Since the magnetoelectric (ME) effect is relativistically small in traditional antiferromagnetic compounds like Cr2O3 (max. αzz 4ps/m ) and also cross- coupling between ferroic order parameters is typically small in the modern multiferroics, it is a challenge to electrically induce sufficient magnetization required for the envisioned device applications. A straightforward approach is to increase the electric field at constant voltage by reducing the thickness of the ME material to thin films of a few nm. Since magnetism is known to be affected by geometrical confinement thickness dependence of the ME effect in thin film Cr2O3 is expected. We grow (111) textured Cr2O3 films with various thicknesses below 500 nm and study the ME effect for various ME annealing conditions as a function of temperature with the help of Kerr-magnetometry. [1] P. Borisov et al. Phys. Rev. Lett. 94, 117203 (2005). [2] Ch. Binek, B.Doudin, J. Phys. Condens. Matter 17, L39 (2005). [3] R. Ramesh and Nicola A. Spaldin 2007 Nature Materials 6 21.

  20. Microwave dielectric properties of BiFeO3 thin film prepared by aqueous chemical solution deposition method

    Directory of Open Access Journals (Sweden)

    Ričardas Sobiestianskas

    2009-12-01

    Full Text Available We report high frequency dielectric properties of multiferroic BiFeO3 (BFO thin film deposited by means of aqueous chemical solution deposition on platinized silicon substrate. The structure analysis of the BFO performed by X-ray diffraction and energy dispersive analysis showed pure, single-phase quality of the thin films. The impedance measurements were performed by vector network analyzer in frequency range 100 MHz to 10 GHz at ambient temperature. The film leakage currents dominate dielectric losses at low frequencies. The dielectric constant of the film is around 40. An internal charged defects acting as energy traps for electrons dominate dielectric losses in the frequency region above 4 GHz.

  1. Hybrid ferroelectric phase transition in multiferroic Ca.sub.3./sub.Mn.sub.2./sub.O.sub.7./sub

    Czech Academy of Sciences Publication Activity Database

    Kamba, Stanislav; Adamo, C.; Goian, Veronica; Zhang, H.; Beanland, R.; Gupta, A.S.; Gopalan, V.; Drahokoupil, Jan; Vaněk, Přemysl; Svatuška, Michal; Seiner, Hanuš; Palatinus, Lukáš; Klementová, Mariana; Benedek, N.A.; Reaney, I. M.; Maca, K.; Fennie, C.J.; Schlom, D. G.

    Praha : Institute of Physics, AS CR, 2014 - (Glogarová, M.; Hlinka, J.). s. 82-82 [Czech-polish seminar /21./. 19.05.2014-23.05.2014, Sezimovo Ústí] Institutional support: RVO:68378271 ; RVO:61388998 Keywords : ferroelectric phase transition * multiferroic Subject RIV: BM - Solid Matter Physics ; Magnetism

  2. Structural, Electrical, and Dielectric Properties of Multiferroic-Spinel Ferrite Composites

    Science.gov (United States)

    Nazir, Muhammad Aamir; Ul-Islam, Misbah; Ali, Irshad; Ali, Hassan; Ahmad, Bashir; Ramay, Shahid M.; Raza, Nadeem; Ehsan, Muhammad Fahad; Ashiq, Muhammad Naeem

    2016-02-01

    The present work reports development towards magnetoelectric ceramic composites, i.e., (1- x)Bi0.7Al0.3Mn0.3Fe0.7O3- xLi0.3Zn0.4Fe2.3O4 with x = 0.0, 0.25, 0.35, 0.45, and 1.0. Al- and Mn-doped bismuth multiferroic Bi0.7Al0.3Mn0.3Fe0.7O3 (AMBFO) and Zn-doped lithium ferrite Li0.3Zn0.4 Fe2.3O4 (LZF) were synthesized by the coprecipitation and sol-gel method, respectively. The composite system was synthesized by the conventional solid-state reaction technique followed by heat treatment at 700°C for 6 h. X-ray diffraction (XRD) analysis confirmed the formation of orthorhombic and face-centered cubic phase structure in AMBFO and LZF, respectively. The presence of peaks from both systems in the XRD pattern confirmed composite formation. The metal-to-semiconductor transition temperature decreased from 340 K to 330 K with increase in the LZF content, being mainly due to spin canting and phase structure conversion. The direct-current (DC) electrical resistivity was found to be highest for pure AMBFO and then started to decrease with increase in the Li-Zn ferrite (LZF) content in the composites. The dielectric constant decreased with increase in frequency for all samples, in accordance with Koop's phenomenological theory and the Debye relaxation model. However, the alternating-current (AC) conductivity increased with increase in frequency for all samples, which can be attributed to the conduction mechanism of polaron hopping. These composites open a new approach towards magnetoelectric applications, high-frequency devices, and semiconductor-based solar energy conversion systems.

  3. The magnetic structures and transitions of a potential multiferroic orthoferrite ErFeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Guochu, E-mail: guochu.deng@ansto.gov.au; Maynard-Casely, Helen E.; Avdeev, Maxim; McIntyre, Garry J. [Bragg Institute, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234 (Australia); Guo, Peiyin; Ren, Wei; Cao, Shixun, E-mail: sxcao@shu.edu.cn [Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200444 (China)

    2015-04-28

    Rare-earth orthoferrites are very interesting due to their appealing optical and multiferroic properties. In this study, the magnetic structures and transitions of a typical rare-earth orthoferrite, ErFeO{sub 3}, have been reinvestigated in detail. The spin-reorientation transition of the Fe{sup 3+} magnetic phase and the low-temperature magnetic ordering of Er{sup 3+} were observed by neutron powder diffraction. The corresponding magnetic structures have been solved anew by symmetry analysis and refinement of the diffraction results. The magnetic moments of Fe{sup 3+} align in an antiferromagnetic way along the c axis with a weak ferromagnetic component along the b axis below the Néel temperature and above the spin-reorientation transition. Below the spin-reorientation transition, the Fe{sup 3+} moments rotate into an antiferromagnetic ordering state along the b axis with weak ferromagnetic alignment along the c axis. The spin-reorientation takes place in the bc plane. The Er{sup 3+} moments align antiferromagnetically with a C{sub y} mode below 4.5 K. For the Fe{sup 3+} moments, an additional C{sub x} mode is induced by the ordering of the Er{sup 3+} moments. Namely, they change from G{sub y}F{sub z} mode into C{sub x}G{sub y}F{sub z} mode in the Pnma space-group setting. This study resolves the long-lasting dispute about the magnetic structure of ErFeO{sub 3} at low temperature.

  4. Multiferroic tunnel junctions and ferroelectric control of magnetic state at interface (invited)

    KAUST Repository

    Yin, Y. W.

    2015-03-03

    As semiconductor devices reach ever smaller dimensions, the challenge of power dissipation and quantum effect place a serious limit on the future device scaling. Recently, a multiferroic tunnel junction (MFTJ) with a ferroelectric barrier sandwiched between two ferromagnetic electrodes has drawn enormous interest due to its potential applications not only in multi-level data storage but also in electric field controlled spintronics and nanoferronics. Here, we present our investigations on four-level resistance states, giant tunneling electroresistance (TER) due to interfacial magnetoelectric coupling, and ferroelectric control of spin polarized tunneling in MFTJs. Coexistence of large tunneling magnetoresistance and TER has been observed in manganite/(Ba, Sr)TiO3/manganite MFTJs at low temperatures and room temperature four-resistance state devices were also obtained. To enhance the TER for potential logic operation with a magnetic memory, La0.7Sr0.3MnO3/BaTiO3/La0.5Ca0.5MnO3 /La0.7Sr0.3MnO3 MFTJs were designed by utilizing a bilayer tunneling barrier in which BaTiO3 is ferroelectric and La0.5Ca0.5MnO3 is close to ferromagnetic metal to antiferromagnetic insulator phase transition. The phase transition occurs when the ferroelectric polarization is reversed, resulting in an increase of TER by two orders of magnitude. Tunneling magnetoresistance can also be controlled by the ferroelectric polarization reversal, indicating strong magnetoelectric coupling at the interface.

  5. Reducing error rates in straintronic multiferroic nanomagnetic logic by pulse shaping

    Science.gov (United States)

    Munira, Kamaram; Xie, Yunkun; Nadri, Souheil; Forgues, Mark B.; Salehi Fashami, Mohammad; Atulasimha, Jayasimha; Bandyopadhyay, Supriyo; Ghosh, Avik W.

    2015-06-01

    Dipole-coupled nanomagnetic logic (NML), where nanomagnets (NMs) with bistable magnetization states act as binary switches and information is transferred between them via dipole-coupling and Bennett clocking, is a potential replacement for conventional transistor logic since magnets dissipate less energy than transistors when they switch in a logic circuit. Magnets are also ‘non-volatile’ and hence can store the results of a computation after the computation is over, thereby doubling as both logic and memory—a feat that transistors cannot achieve. However, dipole-coupled NML is much more error-prone than transistor logic at room temperature (\\gt 1%) because thermal noise can easily disrupt magnetization dynamics. Here, we study a particularly energy-efficient version of dipole-coupled NML known as straintronic multiferroic logic (SML) where magnets are clocked/switched with electrically generated mechanical strain. By appropriately ‘shaping’ the voltage pulse that generates strain, we show that the error rate in SML can be reduced to tolerable limits. We describe the error probabilities associated with various stress pulse shapes and discuss the trade-off between error rate and switching speed in SML.The lowest error probability is obtained when a ‘shaped’ high voltage pulse is applied to strain the output NM followed by a low voltage pulse. The high voltage pulse quickly rotates the output magnet’s magnetization by 90° and aligns it roughly along the minor (or hard) axis of the NM. Next, the low voltage pulse produces the critical strain to overcome the shape anisotropy energy barrier in the NM and produce a monostable potential energy profile in the presence of dipole coupling from the neighboring NM. The magnetization of the output NM then migrates to the global energy minimum in this monostable profile and completes a 180° rotation (magnetization flip) with high likelihood.

  6. Multiferroic properties of Y-doped BiFeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Luo Lirong; Wei Wei [School of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Yuan Xueyong [Department of Physics, Southeast University, Nanjing 211189 (China); Shen Kai, E-mail: shenkai84@nuaa.edu.cn [School of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Xu Mingxiang [Department of Physics, Southeast University, Nanjing 211189 (China); Xu Qingyu, E-mail: xuqingyu@seu.edu.cn [Department of Physics, Southeast University, Nanjing 211189 (China); Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 210096 (China)

    2012-11-05

    Highlights: Black-Right-Pointing-Pointer Y with concentration up to 0.30 has been doped into BiFeO{sub 3}. Black-Right-Pointing-Pointer The structure changes from R3c to Pn2{sub 1}a with x above 0.20 in Bi{sub 1.04-x}Y{sub x}FeO{sub 3}. Black-Right-Pointing-Pointer Strongly enhanced room temperature ferromagnetism and improved ferroelectricity have been observed in Bi{sub 0.74}Y{sub 0.30}FeO{sub 3}. - Abstract: Bi{sub 1.04-x}Y{sub x}FeO{sub 3} ceramics with x up to 0.30 were prepared by a tartaric acid modified sol-gel method. The crystal structure transformed from rhombohedral (R3c) to orthorhombic (Pn2{sub 1}a) with increasing Y doping concentration, which was confirmed by the X ray diffraction (XRD) and Raman measurements. With increasing Y doping concentration x, the leakage current was effectively suppressed, and the room temperature ferromagnetism was strongly enhanced with increasing x to 0.30. Clear room temperature ferromagnetism with saturate magnetization of about 0.31 emu/g and ferroelectric properties with 25 {mu}C/cm{sup 2} under electric field of 120 kV/cm have been observed in orthorhombic Bi{sub 0.74}Y{sub 0.30}FeO{sub 3}, suggesting the potential multiferroic applications.

  7. Multiferroic properties of Pb{sub 2}Fe{sub 2}O{sub 5} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Min [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China); Tan, Guolong, E-mail: gltan@whut.edu.cn [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070 (China)

    2011-03-15

    Research highlights: {yields} Simultaneous occurrence of ferromagnetism and ferroelectricity in Pb{sub 2}Fe{sub 2}O{sub 5} ceramics. {yields} The off-centers of shifted Pb{sup 2+} ions as well as the FeO{sub 6} octahedra in the 'Pb{sub 2}Fe{sub 2}O{sub 5}' lead to a ferroelectric polarization. {yields} Pb{sub 2}Fe{sub 2}O{sub 5} ceramic demonstrates ferromagnetic order state due to the spin arrangement in the double chains of FeO{sub 5} tetrahedral pyramids. -- Abstract: Pb{sub 2}Fe{sub 2}O{sub 5} (PFO) powders in monoclinic structure have been synthesized using lead acetate in glycerin and ferric acetylacetonate as the precursor. The powders were pressed into pellets, which were sintered into ceramics at 800 {sup o}C for 1 h. The morphology and structure have been determined by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Polarization was observed in Pb{sub 2}Fe{sub 2}O{sub 5} ceramics at room temperature, exhibiting a clear ferroelectric hysteresis loop. The remanent polarization of Pb{sub 2}Fe{sub 2}O{sub 5} ceramic is estimated to be Pr {approx} 0.22 {mu}C/cm{sup 2}. The origin of the polarization may be attributed to the off-centers of shifted Pb{sup 2+} ions as well as the FeO{sub 6} octahedra in the perovskite-based structure of Pb{sub 2}Fe{sub 2}O{sub 5}. Magnetic hysteresis loop was also observed at room temperature. The Pb{sub 2}Fe{sub 2}O{sub 5} ceramic shows coexistence of ferroelectricity and ferromagnetism. It provides a new field of research for complex oxides with multiferroic properties.

  8. Multiferroic tunnel junctions and ferroelectric control of magnetic state at interface (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Y. W.; Raju, M.; Li, Qi, E-mail: Qil1@psu.edu [Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Hu, W. J. [Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia); Burton, J. D.; Gruverman, A.; Tsymbal, E. Y. [Department of Physics and Astronomy and Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, Nebraska 68588-0299 (United States); Kim, Y.-M.; Borisevich, A. Y.; Pennycook, S. J. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Yang, S. M.; Noh, T. W. [IBS-Center for Functional Interfaces of Correlated Electron Systems, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Li, X. G. [Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, University of Science and Technology of China, Hefei 230026 (China); Zhang, Z. D. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2015-05-07

    As semiconductor devices reach ever smaller dimensions, the challenge of power dissipation and quantum effect place a serious limit on the future device scaling. Recently, a multiferroic tunnel junction (MFTJ) with a ferroelectric barrier sandwiched between two ferromagnetic electrodes has drawn enormous interest due to its potential applications not only in multi-level data storage but also in electric field controlled spintronics and nanoferronics. Here, we present our investigations on four-level resistance states, giant tunneling electroresistance (TER) due to interfacial magnetoelectric coupling, and ferroelectric control of spin polarized tunneling in MFTJs. Coexistence of large tunneling magnetoresistance and TER has been observed in manganite/(Ba, Sr)TiO{sub 3}/manganite MFTJs at low temperatures and room temperature four-resistance state devices were also obtained. To enhance the TER for potential logic operation with a magnetic memory, La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/BaTiO{sub 3}/La{sub 0.5}Ca{sub 0.5}MnO{sub 3} /La{sub 0.7}Sr{sub 0.3}MnO{sub 3} MFTJs were designed by utilizing a bilayer tunneling barrier in which BaTiO{sub 3} is ferroelectric and La{sub 0.5}Ca{sub 0.5}MnO{sub 3} is close to ferromagnetic metal to antiferromagnetic insulator phase transition. The phase transition occurs when the ferroelectric polarization is reversed, resulting in an increase of TER by two orders of magnitude. Tunneling magnetoresistance can also be controlled by the ferroelectric polarization reversal, indicating strong magnetoelectric coupling at the interface.

  9. Stabilization of weak ferromagnetism by strong magnetic response to epitaxial strain in multiferroic BiFeO3.

    Science.gov (United States)

    Dixit, Hemant; Lee, Jun Hee; Krogel, Jaron T; Okamoto, Satoshi; Cooper, Valentino R

    2015-01-01

    Multiferroic BiFeO3 exhibits excellent magnetoelectric coupling critical for magnetic information processing with minimal power consumption. However, the degenerate nature of the easy spin axis in the (111) plane presents roadblocks for real world applications. Here, we explore the stabilization and switchability of the weak ferromagnetic moments under applied epitaxial strain using a combination of first-principles calculations and group-theoretic analyses. We demonstrate that the antiferromagnetic moment vector can be stabilized along unique crystallographic directions ([110] and [-110]) under compressive and tensile strains. A direct coupling between the anisotropic antiferrodistortive rotations and the Dzyaloshinskii-Moria interactions drives the stabilization of the weak ferromagnetism. Furthermore, energetically competing C- and G-type magnetic orderings are observed at high compressive strains, suggesting that it may be possible to switch the weak ferromagnetism "on" and "off" under the application of strain. These findings emphasize the importance of strain and antiferrodistortive rotations as routes to enhancing induced weak ferromagnetism in multiferroic oxides. PMID:26246030

  10. Crystallographic, magnetic and dielectric studies of the potential multiferroic cryolite (NH 4) 3FeF 6

    Science.gov (United States)

    Goff, Richard J.; Tang, Chiu C.; Parker, Julia E.; Morrison, Finlay D.; Lightfoot, Philip

    2011-05-01

    The cryolite phase (NH 4) 3FeF 6 has been studied using variable temperature X-ray powder diffraction, together with dielectric and magnetic measurements, in order to resolve its potential multiferroic properties. The X-ray data reveal a direct transition from cubic to triclinic symmetry between 270 and 250 K, consistent with earlier reports of a ferroelectric TC of 264 K. The crystal structure of the low temperature phase has been modelled approximately in a pseudo-tetragonal, triclinic space group F1, a = 8.98258(9) Å, b = 8.99631(9) Å, c = 9.27961(9) Å, α = 90.039(1)°, β = 90.451(1)° and γ = 90.339(1)° (at 100 K) but weak superlattice reflections remain unindexed, suggesting the true unit cell to be larger. Electrical measurements indicted an increase in capacitance above 260 K, however this was accompanied by an increase in dielectric loss and so is inconclusive evidence of a ferroelectric-paraelectric phase transition. Polarisation-field loops were not possible due to overriding leakage. Magnetic susceptibility data show paramagnetic behaviour with no indication of long-range order above 2 K, and only weak antiferromagnetic interactions ( θ ˜ -7 K). This therefore clearly demonstrates the material is not multiferroic.

  11. Functional properties of Sm2NiMnO6 multiferroic ceramics prepared by spark plasma sintering

    International Nuclear Information System (INIS)

    In the present work, it was reported for the first time the new synthesis of Sm2NiMnO6 double perovskite oxides by sol–gel auto-combustion method. The Rietveld analysis of the X-ray ceramics diffraction pattern recorded at room temperature for Sm2NiMnO6 ceramics sintered at 1000 °C/5 min from powders obtained at 700 °C/7 h confirm the formation of the double perovskite with a monoclinic structure and the space group P21/n. The HRTEM analysis shows clear lattice fringes that confirm a high crystallinity level of the material corresponding to the monoclinic structure. The non-linear dielectric character was checked for the first time in Sm2NiMnO6 double perovskite and the results reveals a strong nonlinearity and a small hysteretic behaviour. The present structural, magnetic and dielectric data make the Sm2NiMnO6 system due to its multiferroic character a promising candidate to different modern electronic devices applications. - Highlights: • The Sm2NiMnO6 double perovskite were prepared by sol–gel auto-combustion method. • The Rietveld and HRTEM analysis confirm a double perovskite monoclinic structure. • The non-linear character reveals a strong nonlinearity. • The magnetic transitions indicate a change in the spin ordering. • The Sm2NiMnO6 system is a promising multiferroic candidate to modern applications

  12. Reversible electrically-driven magnetic domain wall rotation in multiferroic heterostructures to manipulate suspended on-chip magnetic particles

    Science.gov (United States)

    Nowakowski, Mark; Sohn, Hyunmin; Liang, Cheng-Yen; Hockel, Joshua; Wetzlar, Kyle; Keller, Scott; McLellan, Brenda; Marcus, Matthew; Doran, Andrew; Young, Anthony; Kläui, Mathias; Carman, Gregory; Bokor, Jeffrey; Candler, Robert

    2015-03-01

    We experimentally demonstrate reversible electrically-driven, strain-mediated domain wall (DW) rotation in Ni rings fabricated on piezoelectric [Pb(Mg1/3Nb2/3) O3]0.66-[PbTiO3]0.34 (PMN-PT) substrates. An electric field applied across the PMN-PT substrate induces a strain in the Ni rings producing DW rotation around the ring toward the dominant PMN-PT strain axis by inverse magnetostriction. We observe DWs reversibly cycled between their initial and rotated state as a function of the applied electric field with x-ray magnetic circular dichroism photo-emission electron microscopy. The DW rotation is analytically predicted using a fully coupled micromagnetic/elastodyanmic multi-physics simulation to verify that the experimental behavior is caused by the electrically-generated strain in this multiferroic system. Finally, this DW rotation is used to capture and manipulate magnetic particles in a fluidic environment to demonstrate a proof-of-concept energy-efficient pathway for multiferroic-based lab-on-a-chip applications. Supported by TANMS (NSF 11-537), E3S, US Dept of Energy (DE-AC02-05CH11231), EU, and DFG.

  13. Strong magnetoelectric coupling in ferrite/ferroelectric multiferroic heterostructures derived by low temperature spin-spray deposition

    Energy Technology Data Exchange (ETDEWEB)

    Liu, M; Obi, O; Lou, J; Stoute, S; Sun, N X [Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115 (United States); Cai, Z; Ziemer, K, E-mail: nian@ece.neu.ed [Department of Chemical Engineering, Northeastern University, Boston, MA 02115 (United States)

    2009-02-21

    Strong magnetoelectric (ME) interaction was demonstrated at both dc and microwave frequencies in a novel Zn{sub 0.1}Fe{sub 2.9}O{sub 4}/PMN-PT (lead magnesium niobate-lead titanate) multiferroic heterostructure, which was prepared by spin-spray depositing a Zn{sub 0.1}Fe{sub 2.9}O{sub 4} film on a single-crystal PMN-PT substrate at a low temperature of 90 deg. C. A large electric-field induced ferromagnetic resonance field shift up to 140 Oe was observed, corresponding to an ME coefficient of 23 Oe cm kV{sup -1}. In addition, a large electrostatic field tuning of the magnetic hysteresis loops was observed with a large squareness ratio change of 18%. The spin-spray deposited ferrite/piezoelectric multiferroic heterostructures exhibiting strong ME interactions at both dc and microwave frequencies provide great opportunities for novel electrostatically tunable microwave magnetic devices synthesized at a low temperature.

  14. Electrically driven magnetic domain wall rotation in multiferroic heterostructures to manipulate suspended on-chip magnetic particles.

    Science.gov (United States)

    Sohn, Hyunmin; Nowakowski, Mark E; Liang, Cheng-yen; Hockel, Joshua L; Wetzlar, Kyle; Keller, Scott; McLellan, Brenda M; Marcus, Matthew A; Doran, Andrew; Young, Anthony; Kläui, Mathias; Carman, Gregory P; Bokor, Jeffrey; Candler, Robert N

    2015-05-26

    In this work, we experimentally demonstrate deterministic electrically driven, strain-mediated domain wall (DW) rotation in ferromagnetic Ni rings fabricated on piezoelectric [Pb(Mg1/3Nb2/3)O3]0.66-[PbTiO3]0.34 (PMN-PT) substrates. While simultaneously imaging the Ni rings with X-ray magnetic circular dichroism photoemission electron microscopy, an electric field is applied across the PMN-PT substrate that induces strain in the ring structures, driving DW rotation around the ring toward the dominant PMN-PT strain axis by the inverse magnetostriction effect. The DW rotation we observe is analytically predicted using a fully coupled micromagnetic/elastodynamic multiphysics simulation, which verifies that the experimental behavior is caused by the electrically generated strain in this multiferroic system. Finally, this DW rotation is used to capture and manipulate micrometer-scale magnetic beads in a fluidic environment to demonstrate a proof-of-concept energy-efficient pathway for multiferroic-based lab-on-a-chip applications. PMID:25906195

  15. Magneto-structural study of the multiferroic BiFeO3–SrTiO3

    International Nuclear Information System (INIS)

    The structural and magnetic study of the pseudo-binary multiferroic (1−x)BiFeO3−(x)SrTiO3has been investigated as a function of composition and temperature. In contrary to the previous studies, detailed examination revealed that the reported anomaly in the magnetization at x–0.30 does not occur at the composition induced rhombohedral–cubic phase boundary, but within the rhombohedral phase itself. The rhombohedral to cubic transition occurs at x>0.4. Evidence of magneto-elastic coupling near the Neel temperature and nucleation-growth mode of the rhombohedral–cubic transformation, with both the phases coexisting over a range of temperature was found. - Highlights: • The paper reports magneto-structural study of BiFeO3–SrTiO3 multiferroic. • Evidence of magneto-elastic coupling near the Neel temperature is shown. • The magnetization anomaly at 30 mol% SrTiO3 occurs within the rhombohedral phase

  16. Stabilization of weak ferromagnetism by strong magnetic response to epitaxial strain in multiferroic BiFeO3

    Science.gov (United States)

    Dixit, Hemant; Hee Lee, Jun; Krogel, Jaron T.; Okamoto, Satoshi; Cooper, Valentino R.

    2015-08-01

    Multiferroic BiFeO3 exhibits excellent magnetoelectric coupling critical for magnetic information processing with minimal power consumption. However, the degenerate nature of the easy spin axis in the (111) plane presents roadblocks for real world applications. Here, we explore the stabilization and switchability of the weak ferromagnetic moments under applied epitaxial strain using a combination of first-principles calculations and group-theoretic analyses. We demonstrate that the antiferromagnetic moment vector can be stabilized along unique crystallographic directions ([110] and [-110]) under compressive and tensile strains. A direct coupling between the anisotropic antiferrodistortive rotations and the Dzyaloshinskii-Moria interactions drives the stabilization of the weak ferromagnetism. Furthermore, energetically competing C- and G-type magnetic orderings are observed at high compressive strains, suggesting that it may be possible to switch the weak ferromagnetism “on” and “off” under the application of strain. These findings emphasize the importance of strain and antiferrodistortive rotations as routes to enhancing induced weak ferromagnetism in multiferroic oxides.

  17. Crystalline and spin chiralities in multiferroics with langasite-type structure and Fe1–xCoxSi crystals

    International Nuclear Information System (INIS)

    It is shown that, when magnetic ordering occurs in layered iron-containing langasites (sp. gr. P321), one of the reasons for spin chiralities of different signs is the presence of structural chirality (the existence of inversion twins), which, in turn, is due to the nonsymmetricity of these crystals. Spin helicoids arise in these multiferroics at split sites of Fe3+ ions below the Néel point. The direction of electric polarization vectors coincides with the direction of the magnetic helicoid axes because of the piezoelectric properties of these materials. Due to the magnetostriction effects, structural chirality wave vector kz exceeds the magnetic helicoid wave vector by a factor of 2: kz = 2qz. The temperatures of transitions to the chiral structural and chiral magnetic states may differ. In particular, if the structural transition initial temperature exceeds the magnetic transition temperature (ΤU> ΤM), structural displacements may arise in the absence of magnetism at ΤM < Τ < ΤU. In noncentrosymmetric Fe1–xCoxSi crystals (sp. gr. P213), which are not multiferroics, magnetic chirality is due to the Dzyaloshinski–Moriya interaction. The dependence of the moduli of incommensurate wave number of the corresponding helicoid on the atomic composition of the crystals under consideration is nonmonotonic

  18. High Pressure Experimental Studies on CuO: Indication of Re-entrant Multiferroicity at Room Temperature.

    Science.gov (United States)

    Jana, Rajesh; Saha, Pinku; Pareek, Vivek; Basu, Abhisek; Kapri, Sutanu; Bhattacharyya, Sayan; Mukherjee, Goutam Dev

    2016-01-01

    We have carried out detailed experimental investigations on polycrystalline CuO using dielectric constant, dc resistance, Raman spectroscopy and X-ray diffraction measurements at high pressures. Observation of anomalous changes both in dielectric constant and dielectric loss in the pressure range 3.7-4.4 GPa and reversal of piezoelectric current with reversal of poling field direction indicate to a change in ferroelectric order in CuO at high pressures. A sudden jump in Raman integrated intensity of Ag mode at 3.4 GPa and observation of Curie-Weiss type behaviour in dielectric constant below 3.7 GPa lends credibility to above ferroelectric transition. A slope change in the linear behaviour of the Ag mode and a minimum in the FWHM of the same indicate indirectly to a change in magnetic ordering. Since all the previous studies show a strong spin-lattice interaction in CuO, observed change in ferroic behaviour at high pressures can be related to a reentrant multiferroic ordering in the range 3.4 to 4.4 GPa, much earlier than predicted by theoretical studies. We argue that enhancement of spin frustration due to anisotropic compression that leads to change in internal lattice strain brings the multiferroic ordering to room temperature at high pressures. PMID:27530329

  19. Effect of spin excitations with simultaneous magnetic- and electric-dipole character on the static magnetoelectric properties of multiferroic materials

    Science.gov (United States)

    Szaller, Dávid; Bordács, Sándor; Kocsis, Vilmos; Rõõm, Toomas; Nagel, Urmas; Kézsmárki, István

    2014-05-01

    We derive a sum rule to demonstrate that the static magnetoelectric (ME) effect is governed by optical transitions that are simultaneously excited by the electric and magnetic components of light. The ME sum rule is applicable to a broad class of materials lacking the spatial inversion and the time-reversal symmetries, including multiferroic compounds. Due to the dynamical ME effect, the optical excitations in these materials can exhibit directional dichroism, i.e., the absorption coefficient can be different for counter-propagating light beams. According to the ME sum rule, the magnitude of the linear ME effect of a material is mainly determined by the directional dichroism of its low-energy optical excitations. An application of the sum rule to the multiferroic Ba2CoGe2O7, Sr2CoSi2O7, and Ca2CoSi2O7 shows that in these compounds the static ME effect is mostly governed by the directional dichroism of the spin-wave excitations in the giga-terahertz spectral range. On this basis, we argue that the studies of directional dichroism and the application of the ME sum rule promote the synthesis of new materials with large static ME effect.

  20. Theory of domain wall motion mediated magnetoelectric effects in a multiferroic composite

    Science.gov (United States)

    Petrov, V. M.; Srinivasan, G.

    2014-10-01

    A model is discussed for magnetoelectric (ME) interactions originating from the motion of magnetic domain walls (DWs) in a multiferroic composite of orthoferrites RFeO3 (RFO) with magnetic stripe domains and a piezoelectric such as lead magnesium niobate-lead titanate (PMN-PT). The DWs in RFO can be set in motion with an ac magnetic field up to a critical speed of 20 km/s, the highest for any magnetic system, leading to the excitation of bulk and shear magnetoacoustic waves. Thus, the ME coupling will arise from flexural deformation associated with DW motion (rather than the Joule magnetostriction mediated coupling under a static or quasistatic condition). A c plane orthoferrite with a single Néel-type DW in the bc plane and an ac magnetic field H along the c axis is assumed. The deflection in the bilayer due to DW motion is obtained when the DW velocity is a linear function H and the resulting induced voltage across PMN-PT is estimated. It is shown that a combination of spatial and time harmonics of the bending deformation leads to (i) a linear ME coefficient defined by αE=E/H and (ii) a quadratic ME coefficient αEQ=E/H2. The model is applied to yttrium orthoferrites (YFO) and a PMN-PT bilayer since YFO has one of the highest DW mobility amongst the orthoferrites. The coefficient αE is dependent on the DW position, and it is maximum when the DW equilibrium position is at the center of the sample. In YFO/PMN-PT the estimated low-frequency αE ˜ 30 mV/cm Oe and resonance value is 1.5 V/(cm Oe). Since orthoferrites (and PMN-PT) are transparent in the visible region and have a large Faraday rotation, the DW dynamics and the ME coupling could be studied simultaneously. The theory discussed here is of interest for studies on ME coupling and for applications such as magnetically controlled electro-optic devices.

  1. Synthesis, microstructure and properties of BiFeO3-based multiferroic materials: A review

    Directory of Open Access Journals (Sweden)

    Bernardo, M. S.

    2014-02-01

    Full Text Available BiFeO3-based materials are currently one of the most studied multiferroics due to their possible applications at room temperature. However, among the large number of published papers there is much controversy. For example, possibility of synthesizing a pure BiFeO3 phase is still source of discussion in literature. Not even the nature of the binary Bi2O3-Fe2O3 diagram has been clarified yet. The difficulty in controlling the formation of parasite phases reaches the consolidation step. Accordingly, the sintering conditions must be carefully determined both to get dense materials and to avoid bismuth ferrite decomposition. However, the precise conditions to attain dense bismuth ferrite materials are frequently contradictory among different works. As a consequence, the reported properties habitually result opposed and highly irreproducible hampering the preparation of BiFeO3 materials suitable for practical applications. In this context, the purpose of the present review is to summarize the main researches regarding BiFeO3 synthesis, microstructure and properties in order to provide an easier understanding of these materials.Los materiales basados en BiFeO3 son en la actualidad uno de los multiferroicos más estudiados debido a sus posibles aplicaciones a temperatura ambiente. Sin embargo, entre la multitud de trabajos publicados referentes a estos materiales existe mucha controversia. Por ejemplo, la posibilidad de sintetizar una fase BiFeO3 pura es aún objeto de discusión en la bibliografía y la naturaleza de los diagramas de fases del sistema Bi2O3-Fe2O3 aún no está clara. La dificultad para controlar las fases parásitas se extiende al proceso de consolidación por lo que las condiciones de sinterización deben ser cuidadosamente controladas para obtener materiales densos y al mismo tiempo evitar la descomposición de la ferrita. No obstante, las condiciones precisas para obtener materiales densos de BiFeO3 son frecuentemente

  2. Improved ferroelectric polarization of V-doped Bi6Fe2Ti3O18 thin films prepared by a chemical solution deposition

    International Nuclear Information System (INIS)

    We prepared V-doped Bi6Fe2Ti3O18 thin films on Pt/Ti/SiO2/Si (100) substrates by using a chemical solution deposition route and investigated the doping effect on the microstructure, dielectric, leakage, and ferroelectric properties of Bi6Fe2Ti3O18 thin films. The Bi5.97Fe2Ti2.91V0.09O18 thin film exhibits improved dielectric properties, leakage current, and ferroelectric properties. The incorporation of vanadium resulted in a substantially enhanced remnant polarization (2Pr) over 30 μC/cm2 in Bi5.97Fe2Ti2.91V0.09O18 thin film compared with 10 μC/cm2 in Bi6Fe2Ti3O18 thin film. It is demonstrated that the improved properties may stem from the improvement of crystallinity of the films with the contribution of suppressed oxygen vacancies and decreased mobility of oxygen vacancies caused by the V-doping. The results will provide a guidance to optimize the ferroelectric properties in Bi6Fe2Ti3O18 thin films by chemical solution deposition, which is important to further explore single-phase multiferroics in the n = 5 Aurivillius thin films

  3. Charge, spin and orbital order in the candidate multiferroic material LuFe2O4

    International Nuclear Information System (INIS)

    This thesis is a detailed study of the magnetic, structural and orbital order parameters of the candidate multiferroic material LuFe2O4. Multiferroic oxides with a strong magnetoelectric coupling are of high interest for potential information technology applications, but they are rare because the traditional mechanism of ferroelectricity is incompatible with magnetism. Consequently, much attention is focused on various unconventional mechanisms of ferroelectricity. Of these, ferroelectricity originating from charge ordering (CO) is particularly intriguing because it potentially combines large electric polarizations with strong magneto-electric coupling. However, examples of oxides where this mechanism occurs are exceedingly rare and none is really well understood. LuFe2O4 is often cited as the prototypical example of CO-based ferroelectricity. In this material, the order of Fe valences has been proposed to render the triangular Fe/O bilayers polar by making one of the two layers rich in Fe2+ and the other rich in Fe3+, allowing for a possible ferroelectric stacking of the individual bilayers. Because of this new mechanism for ferroelectricity, and also because of the high transition temperatures of charge order (TCO ∝320K) and ferro magnetism (TN∝240 K) LuFe2O4 has recently attracted increasing attention. Although these polar bilayers are generally accepted in the literature for LuFe2O4, direct proof is lacking. An assumption-free experimental determination of whether or not the CO in the Fe/O bilayers is polar would be crucial, given the dependence of the proposed mechanism of ferroelectricity from CO in LuFe2O4 on polar bilayers. This thesis starts with a detailed characterization of the macroscopic magnetic properties, where growing ferrimagnetic contributions observed in magnetization could be ascribed to increasing oxygen off-stoichiometry. The main focus is on samples exhibiting a sharp magnetic transition to long-range spin order at TN∝240 K

  4. Thermal evolution of the full three-dimensional magnetic excitations in the multiferroic BiFeO3

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhijun [ORNL; Wen, Jinsheng [University of California, Berkeley; Berlijn, Tom [ORNL; Gehring, Peter M [ORNL; Stock, Christopher K [ORNL; Stone, Matthew B [ORNL; Gu, G. D. [Brookhaven National Laboratory (BNL); Shapiro, S. M. [Brookhaven National Laboratory (BNL); Birgeneau, R J [University of California, Berkeley & LBNL; Xu, Guangyong [Brookhaven National Laboratory (BNL)

    2012-01-01

    We present neutron inelastic scattering measurements of the full three-dimensional spin-wave dispersion in the multiferroic material BiFeO3 for temperatures from 5K to 700K. Despite the presence of strong electromagnetic coupling, the magnetic excitations behave like conventional magnons over all parts of the Brillouin zone. At low temperature the spin-waves are well-defined coherent modes, described by a classical model for a G-type antiferromagnet. A softening of the spin-wave velocity and broadening in energy is already present at room temperature, which is well below the N eel temperature TN 640K, and increases on heating. In addition, a strong hybridization of the Fe 3d and O 2p states is found to modify the distribution of the spin-wave spectral weight significantly, which implies that the spins are not restricted to the Fe atomic sites as previously believed.

  5. Influence of Dy and Cu doping on the room temperature multiferroic properties of BiFeO3

    Science.gov (United States)

    Priya, A. Sathiya; Banu, I. B. Shameem; Anwar, Shahid

    2016-03-01

    A series of Bi1-xDyxFe0.98Cu0.02O3 (x=1%, 2%, 3%, 4%, 5%) nanoparticles were prepared by sol-gel method. X-ray diffraction patterns reveal that the undoped and doped samples crystallize in rhombohedral structure. Enhanced magnetic properties are observed for the doped nanoparticles as compared to undoped BiFeO3 (BFO) and when Dy substitution to Bi site is increased, the saturation magnetization (Ms) and remnant magnetization (Mr) show a remarkable increase. The Dy and Cu doping has improved the ferroelectric properties of the BFO. The measured magnetoelectric effect shows remarkable enhancement for the doped BFO as compared to the undoped BFO. The measured magnetic and ferroelectric properties of the doped samples has demonstrated that Dy and Cu doping can significantly improve the multiferroic properties of BiFeO3.

  6. Structural study in ceramic multiferroic Co3TeO6 and analysis of possible Co-Co networks

    International Nuclear Information System (INIS)

    We show that there exist four networks (Co1-Co4, Co2-Co3-Co5, Co1-Co5 and Co2-Co3-Co4) in contrast to earlier observations of two networks (Co1-Co4 and Co2-Co3-Co5) in Co3TeO6 (CTO) multiferroic [Phys. Rev. B 88, 184427 (2013)]. Due to five crystallographically different sites of Co ions coordinated by [IV], [V] and [VI] oxygen atoms, the coordination polyhedra exhibit strong distortions from their respective ideal polyhedra, and thus potentially allow to resolve low-symmetry crystal field splittings of d-d electronic transitions. Our structural analysis using Rietveld refinements on the room temperature Synchrotron X-ray Diffraction data indicates possible magnetic order, and may provide a basis for the complex and multiple magnetic transitions of CTO at low temperature

  7. Ferroelectric properties and dielectric responses of multiferroic BiFeO{sub 3} films grown by RF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Qi Xiaoding; Tsai, P-C; Chen, I-G [Department of Materials Science and Engineering, National Cheng Kung University, Taiwan (China); Chen, Y-C; Ko, C-H; Huang, J-C-A [Department of Physics, National Cheng Kung University, Taiwan (China)], E-mail: xqi045@mail.ncku.edu.tw

    2008-12-07

    Multiferroic BiFeO{sub 3} films have been grown on LaNiO{sub 3-x}/SrTiO{sub 3} and Pt/Si substrates by RF magnetron sputtering. The films showed fully saturated ferroelectric hysteresis loops with large remanent polarization of 64 {mu}C cm{sup -2}, suitable for most device applications. Piezoresponse force microscopy confirmed that the films were electrically writable. In addition to the high-frequency intrinsic dielectric loss of epitaxial films, the Argand diagram also revealed low-frequency contributions from both dc conductivity and interfacial polarization at electrodes. For polycrystalline films on Pt/Si, the dominant contribution to dielectric loss was space charge polarization at grain boundaries. (fast track communication)

  8. Electric tuning of magnetization dynamics and electric field-induced negative magnetic permeability in nanoscale composite multiferroics

    Science.gov (United States)

    Jia, Chenglong; Wang, Fenglong; Jiang, Changjun; Berakdar, Jamal; Xue, Desheng

    2015-06-01

    Steering magnetism by electric fields upon interfacing ferromagnetic (FM) and ferroelectric (FE) materials to achieve an emergent multiferroic response bears a great potential for nano-scale devices with novel functionalities. FM/FE heterostructures allow, for instance, the electrical manipulation of magnetic anisotropy via interfacial magnetoelectric (ME) couplings. A charge-mediated ME effect is believed to be generally weak and active in only a few angstroms. Here we present an experimental evidence uncovering a new magnon-driven, strong ME effect acting on the nanometer range. For Co92Zr8 (20 nm) film deposited on ferroelectric PMN-PT we show via ferromagnetic resonance (FMR) that this type of linear ME allows for electrical control of simultaneously the magnetization precession and its damping, both of which are key elements for magnetic switching and spintronics. The experiments unravel further an electric-field-induced negative magnetic permeability effect.

  9. Large microwave tunability of GaAs-based multiferroic heterostructure for applications in monolithic microwave integrated circuits

    Energy Technology Data Exchange (ETDEWEB)

    Chen Yajie; Gao Jinsheng; Vittoria, C; Harris, V G [Center for Microwave Magnetic Materials and Integrated Circuits, and the Department of Electrical and Computer Engineering, Northeastern University, Boston, MA 02115 (United States); Heiman, D, E-mail: y.chen@neu.ed [Department of Physics, Northeastern University, Boston, MA 02115 (United States)

    2010-12-15

    Microwave magnetoelectric coupling in a ferroelectric/ferromagnetic/semiconductor multiferroic (MF) heterostructure, consisting of a Co{sub 2}MnAl epitaxial film grown on a GaAs substrate bonded to a lead magnesium niobate-lead titanate (PMN-PT) crystal, is reported. Ferromagnetic resonance measurements were carried out at X-band under the application of electric fields. Results indicate a frequency tuning of 125 MHz for electric field strength of 8 kV cm{sup -1} resulting in a magnetoelectric coupling coefficient of 3.4 Oe cm kV{sup -1}. This work explores the potential of electronically controlled MF devices for use in future monolithic microwave integrated circuits.

  10. Metastable morphotropic phase boundary state in the multiferroic BiFeO3-PbTiO3

    Science.gov (United States)

    Kothai, V.; Prasath Babu, R.; Ranjan, Rajeev

    2013-09-01

    Temperature-time study of the magnetoelectric multiferroic (1-x)BiFeO3-(x)PbTiO3 by x-ray and electron diffraction on the reported morphotropic phase boundary (MPB) compositions revealed that this MPB does not correspond to the equilibrium state. The MPB like state is rather of metastable nature and arise due to kinetic arrest of metastable rhombohedral (R3c) phase, along with the equilibrium tetragonal (P4mm) phase. The life time of the metastable R3c nuclei is very sensitive to composition and temperature, and nearly diverges at x → 0.27. The MPB like state appears only if the system is cooled before the metastable R3c nuclei could vanish. These findings resolve the long standing controversy with regard to seemingly erratic phase formation behaviour reported by different groups and provides a rational basis for developing genuine equilibrium MPB compositions in this system for better piezoelectric properties.

  11. Magnetic structure of multiferroic DyMnO3 studied by resonant soft X-ray scattering

    International Nuclear Information System (INIS)

    In multiferroic DyMnO3, ferroelectricity is induced by a cycloidal magnetic structure of Mn-3d moments. However, it has been shown that ordering of Dy-4f moments strongly influences the ferroelectric properties of this compound. We examined the magnetic structure of Dy-4f moments by resonant magnetic X-ray scattering (RMXS) at the Dy-M5 resonance in detail. As the main result, we show that over a large temperature range of the ferroelectric phase, Dy-4f moments form a magnetic cycloid of a chirality coupled to the direction of the electric polarization. This property can be exploited to map the ferroelectric domain structure at the crystal surface by RMXS.

  12. A multiferroic on the brink: Uncovering the nuances of strain-induced transitions in BiFeO3

    Science.gov (United States)

    Sando, D.; Xu, Bin; Bellaiche, L.; Nagarajan, V.

    2016-03-01

    Bismuth ferrite (BiFeO3) is one of the very few known single-phase multiferroic materials. While the bulk compound is rhombohedral (R), the discovery of an epitaxial strain-induced structural transition into a so-called "super tetragonal phase" (T-phase) in this material incited a flurry of research activity focused on gaining an understanding of this phase transition and its possible functionalities. This metastable phase of BiFeO3 is also multiferroic, with giant ferroelectric polarization and coexisting antiferromagnetic order, but above all it is the strain relaxation-induced phase mixtures and their outstanding piezoelectric and magnetoelectric responses which continue to intrigue and motivate the physicist and materials scientist communities. Here, we review the research into the T-phase and mixed-phase BiFeO3 system. We begin with a brief summary of the history of the T-phase and an analysis of the structure of the various phases reported in the literature. We then address important questions regarding the symmetry and octahedral rotation patterns and the (as yet underexplored) important role of chemistry in the formation of the metastable T-phase. We follow by describing the phase transitions in this material, and how these may hold promise for large magnetoelectric responses. Finally, we point out some experimental challenges inherent to the study of such a system, and potential pathways for how they may be overcome. It is our intention with this work to highlight important issues that, in our opinion, should be carefully considered by the community in order to use this fascinating materials system for a new paradigm of functionality.

  13. Origin of the multiferroicity in BiMn{sub 2}O{sub 5} from first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J., E-mail: zhangjing369@gmail.co [School of Mathematics and Information Science, North China University of Water Resources and Electric Power, Zhengzhou 450011 (China); School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Xu, B.; Li, X.F. [School of Mathematics and Information Science, North China University of Water Resources and Electric Power, Zhengzhou 450011 (China); Yao, K.L. [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); International Center of Materials Physics, Chinese Academy of Science, Shenyang 110015 (China); Liu, Z.L. [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2011-06-15

    Electronic structure, Born effective charges, and spontaneous polarization of multiferroic single crystal BiMn{sub 2}O{sub 5} have been investigated in the framework of density functional theory. The relative stability of the ground state and the origin of multiferroicity for magnetism and ferroelectricity are addressed. The results reveal that the stability of antiferromagnetic (AFM) state is better than the ferromagnetic (FM) and ferrimagnetic configurations. The Born effective charge tensors (Z{sup *}) have been calculated for this compound using a Berry-phase approach, compared to their nominal ionic values, the Z{sup *} of Mn atoms show anomalous difference. By investigating the electric structure of BiMn{sub 2}O{sub 5}, there exists obviously hybridization between Bi 6s and O 2p states, our calculations indicate that the 6s{sup 2} lone pair on the formally trivalent Bi ion plays an important role in inducing the ferroelectric distortion. - Research highlights: Single crystal BiMn{sub 2}O{sub 5} had been first reported in Physical Review B (65, (2002) 144423), the dielectric and magnetoelectric properties seem to indicate the possibility of ferroelectricity. First, based on density functional theory, we investigate the electronic structure and magnetic properties of this compound, our theoretical results are in good agreement with the experimental data. Second, the calculated Born effective charges and spontaneous polarization of BiMn{sub 2}O{sub 5} reveal that this compound shows ferroelectric behavior. In addition, by investigating the electric structure of BiMn{sub 2}O{sub 5}, there exists obviously hybridization between Bi 6s and O 2p states, our calculations indicate that the 6s{sup 2} lone pair on the formally trivalent Bi ion plays an important role in inducing the ferroelectric distortion.

  14. Functional properties of Sm{sub 2}NiMnO{sub 6} multiferroic ceramics prepared by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Gheorghiu, Felicia, E-mail: felicia.gheorghiu@uaic.ro [Dielectrics, Ferroelectrics & Multiferroics Group, Department of Physics, “Al. I. Cuza” Univ., 11 Blvd. Carol I, 700506 Iasi (Romania); RAMTECH Centre, Interdisciplinary Research Department-Field Science, “Al. I. Cuza” Univ., Blvd. Carol I, Nr. 11, 700506 Iasi (Romania); Curecheriu, Lavinia [Dielectrics, Ferroelectrics & Multiferroics Group, Department of Physics, “Al. I. Cuza” Univ., 11 Blvd. Carol I, 700506 Iasi (Romania); Lisiecki, Isabelle [CNRS, Univ Paris 06, UMR 7070, LM2N, bât. F, B.P. 52, 4 place Jussieu, Paris F-75231, Cedex 05 (France); Beaunier, Patricia [UPMC, Univ Paris 06, UMR 7197, LRS, Le Raphaël, 3 rue Galilée, 94200 Ivry (France); Feraru, Simona; Palamaru, Mircea N. [Faculty of Chemistry, “Al. I. Cuza” Univ., 11 Blvd. Carol I, 700506 Iasi (Romania); Musteata, Valentina [“Petru Poni” Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda 41A, 700487 Iasi (Romania); Lupu, Nicoleta [National Institute of Research and Development for Technical Physics, 700050 Iasi (Romania); Mitoseriu, Liliana, E-mail: lmtsr@uaic.ro [Dielectrics, Ferroelectrics & Multiferroics Group, Department of Physics, “Al. I. Cuza” Univ., 11 Blvd. Carol I, 700506 Iasi (Romania)

    2015-11-15

    In the present work, it was reported for the first time the new synthesis of Sm{sub 2}NiMnO{sub 6} double perovskite oxides by sol–gel auto-combustion method. The Rietveld analysis of the X-ray ceramics diffraction pattern recorded at room temperature for Sm{sub 2}NiMnO{sub 6} ceramics sintered at 1000 °C/5 min from powders obtained at 700 °C/7 h confirm the formation of the double perovskite with a monoclinic structure and the space group P2{sub 1}/n. The HRTEM analysis shows clear lattice fringes that confirm a high crystallinity level of the material corresponding to the monoclinic structure. The non-linear dielectric character was checked for the first time in Sm{sub 2}NiMnO{sub 6} double perovskite and the results reveals a strong nonlinearity and a small hysteretic behaviour. The present structural, magnetic and dielectric data make the Sm{sub 2}NiMnO{sub 6} system due to its multiferroic character a promising candidate to different modern electronic devices applications. - Highlights: • The Sm{sub 2}NiMnO{sub 6} double perovskite were prepared by sol–gel auto-combustion method. • The Rietveld and HRTEM analysis confirm a double perovskite monoclinic structure. • The non-linear character reveals a strong nonlinearity. • The magnetic transitions indicate a change in the spin ordering. • The Sm{sub 2}NiMnO{sub 6} system is a promising multiferroic candidate to modern applications.

  15. Multiferroic approach for Cr,Mn,Fe,Co,Ni,Cu substituted BaTiO3 nanoparticles

    Science.gov (United States)

    Verma, Kuldeep Chand; Kotnala, R. K.

    2016-05-01

    Multiferroic magnetoelectric (ME) at room temperature is significant for new design nano-scale spintronic devices. We have given a comparative study to report multiferroicity in BaTM0.01Ti0.99O3 [TM = Cr,Mn,Fe,Co,Ni,Cu (1 mol% each) substituted BaTiO3 (BTO)] nanoparticles. The TM ions influenced both nano-size and lattice distortion of Ti–O6 octahedra to the BTO. X ray diffraction study indicates that the dopant TM could influence lattice constants, distortion, tetragonal splitting of diffraction peaks (002/200) as well as peak shifting of diffraction angle in the BTO lattice. This can induce lattice strain which responsible to oxygen defects formation to mediate ferromagnetism. Also, the lattice strain effect could responsible to reduce the depolarization field of ferroelectricity and provide piezoelectric and magnetostrictive strains to enhance ME coupling. The size of BTO nanoparticles is varied in 13–51 nm with TM doping. The room temperature magnetic measurement indicates antiferromagnetic exchange interactions in BTO lattice with TM ions. The zero-field cooling and field cooling magnetic measurement at 500 Oe indicates antiferromagnetic to ferromagnetic transition. It also confirms that the substitution of Cr, Fe and Co into BTO could induce strong antiferromagnetic behavior. However, the substitutions of Mn, Ni and Cu have weak antiferromagnetic character. The temperature dependent dielectric measurements indicates polarization enhancement that influenced with both nano-size as well TM ions and exhibits ferroelectric phase transition with relaxor-like characteristics. Dynamic ME coupling is investigated, and the longitudinal ME voltage coefficient, α ME is equivalent to linear ME coupling coefficient, α (={\\varepsilon }{{o}}{\\varepsilon }{{r}}{α }{{ME}}) is also calculated.

  16. Converse magnetoelectric coupling in NiFe/Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}–PbTiO{sub 3} nanocomposite thin films grown on Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Ming [School of Materials Science and Engineering and State Key Lab of New Ceramics and Fine Processing, Tsinghua University, Beijing 100084 (China); Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education, Jilin Normal University, Siping 136000 (China); Hu, Jiamian; Wang, Jianjun; Li, Zheng; Shu, Li; Nan, C. W. [School of Materials Science and Engineering and State Key Lab of New Ceramics and Fine Processing, Tsinghua University, Beijing 100084 (China)

    2013-11-04

    Multiferroic NiFe (∼30 nm)/Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}–PbTiO{sub 3}(PMN–PT, ∼220 nm) bilayered thin films were grown on common Pt/Ti/SiO{sub 2}/Si substrates by a combination of off-axis magnetron sputtering and sol-gel spin-coating technique. By using AC-mode magneto-optical Kerr effect technique, the change in the Kerr signal (magnetization) of the NiFe upon applying a low-frequency AC voltage to the PMN–PT film was in situ acquired at zero magnetic field. The obtained Kerr signal versus voltage loop essentially tracks the electromechanical strain curve of the PMN–PT thin film, clearly demonstrating a strain-mediated converse magnetoelectric coupling, i.e., voltage-modulated magnetization, in the NiFe/PMN–PT nanocomposite thin films.

  17. Giant electric field control of magnetism and narrow ferromagnetic resonance linewidth in FeCoSiB/Si/SiO2/PMN-PT multiferroic heterostructures

    Science.gov (United States)

    Gao, Y.; Wang, X.; Xie, L.; Hu, Z.; Lin, H.; Zhou, Z.; Nan, T.; Yang, X.; Howe, B. M.; Jones, J. G.; Brown, G. J.; Sun, N. X.

    2016-06-01

    It has been challenging to achieve combined strong magnetoelectric coupling and narrow ferromagnetic resonance (FMR) linewidth in multiferroic heterostructures. Electric field induced large effective field of 175 Oe and narrow FMR linewidth of 40 Oe were observed in FeCoSiB/Si/SiO2/PMN-PT heterostructures with substrate clamping effect minimized through removing the Si substrate. As a comparison, FeCoSiB/PMN-PT heterostructures with FeCoSiB film directly deposited on PMN-PT showed a comparable voltage induced effective magnetic field but a significantly larger FMR linewidth of 283 Oe. These multiferroic heterostructures exhibiting combined giant magnetoelectric coupling and narrow ferromagnetic resonance linewidth offer great opportunities for integrated voltage tunable RF magnetic devices.

  18. Effect of synthesis conditions on the photocatalytic property of multiferroic BiFeO3 towards the degradation of phenol red

    Science.gov (United States)

    Dhanalakshmi, Radhalayam; Muneeswaran, M.; Giridharan, N. V.

    2016-05-01

    Multiferroic BiFeO3 has been synthesized through hydrothermal route under different reaction conditions. From the basic characterization such as of X-Ray diffraction analysis (XRD), the synthesized Nps were found to having rhombohedral structure with R3c space group. Photodegradation studies of toxic dye phenol red have been investigated under visible light irradiation. Vibrating sample magnetometer (VSM) analysis has been carried out to identify the magnetic properties and recycle ability photocatalysts.

  19. Switching of dipole coupled multiferroic nanomagnets in the presence of thermal noise: reliability analysis of hybrid spintronic-straintronic nanomagnetic logic

    OpenAIRE

    Fashami, Mohammad Salehi; Munira, Kamaram; Bandyopadhyay, Supriyo; Ghosh, Avik W.; Atulasimha, Jayasimha

    2013-01-01

    The stress-induced switching behavior of a multiferroic nanomagnet, dipole coupled to a hard nanomagnet, is numerically studied by solving the stochastic Landau-Lifshitz (LL) equation for a single domain macro-spin state. Different factors were found to affect the switching probability in the presence of thermal noise at room temperature: (i) dipole coupling strength, (ii) stress levels, and (iii) stress withdrawal rates (ramp rates). We report that the thermal broadening of the magnetization...

  20. Phase Structure, Piezoelectric and Multiferroic Properties of SmCoO3-Modified BiFeO3-BaTiO3 Lead-Free Ceramics

    Science.gov (United States)

    Jiang, Na; Tian, Mijie; Luo, Lingling; Zheng, Qiaoji; Shi, Dongliang; Lam, Kwok Ho; Xu, Chenggang; Lin, Dunmin

    2016-01-01

    (0.75- x)BiFeO3-0.25BaTiO3- xSmCoO3 + 1 mol.% MnO2 lead-free multiferroic ceramics were synthesized by a conventional ceramic fabrication technique. The effects of SmCoO3 on phase structure, piezoelectricity and multiferroicity of the ceramics were studied. All the ceramics can be well sintered at a low sintering temperature of 960°C. The crystalline structure of the ceramics is transformed from rhombohedral to tetragonal symmetry with increasing the amount of SmCoO3. A morphotropic phase boundary of rhombohedral and tetragonal phases is formed at x = 0.01-0.04. A small amount of SmCoO3 is shown to improve the ferroelectric, piezoelectric and magnetoelectric properties of the ceramics. For the ceramics with x = 0.01-0.03, enhanced resistivity ( R ˜ 1.2 × 109 Ω cm to 2.1 × 109 Ω cm), piezoelectricity ( d 33 ˜ 65 pC/N to 106 pC/N) and ferroelectricity ( P r ˜ 6.38 μC/cm2 to 22.89 μC/cm2) are obtained. The ferromagnetism of the materials is greatly enhanced by the doping of SmCoO3 such that a very high magnetoelectric coefficient of ˜742 mV/(cm Oe) is obtained at x = 0.01, suggesting a promising potential in multiferroic devices.

  1. Impact of the various spin- and orbital-ordering processes on the multiferroic properties of orthovanadate DyVO3

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Q [Ames Laboratory; Singh, K [Laboratoire CRISMAT; Simon, C [Institut Laue Langevin; Tung, L D [University of Warwick; Balakrishnan, G [University of Warwick; Hardy, V [Laboratoire CRISMAT

    2014-07-01

    The orthovanadate DyVO3 crystal, known to exhibit multiple structural, spin-, and orbital-ordering transitions, is presently investigated on the basis of magnetization, heat capacity, resistivity, dielectric, and polarization measurements. Our main result is experimental evidence for the existence of multiferroicity below a high TC of 108 K over a wide temperature range including different spin-orbital-ordered states. The onset of ferroelectricity is found to coincide with the antiferromagnetic C-type spin-ordering transition taking place at 108 K, which indicates that DyVO3 belongs to type-II multiferroics exhibiting a coupling between magnetism and ferroelectricity. Some anomalies detected on the temperature dependence of electric polarization are discussed with respect to the nature of the spin-orbital-ordered states of the V sublattice and the degree of spin alignment in the Dy sublattice. The orthovanadates RVO3 (R= rare earth or Y) form an important new category for searching for high-TC multiferroics.

  2. Static and dynamic strain coupling behaviour of ferroic and multiferroic perovskites from resonant ultrasound spectroscopy

    Science.gov (United States)

    Carpenter, M. A.

    2015-07-01

    Resonant ultrasound spectroscopy (RUS) provides a window on the pervasive influence of strain coupling at phase transitions in perovskites through determination of elastic and anelastic relaxations across wide temperature intervals and with the application of external fields. In particular, large variations of elastic constants occur at structural, ferroelectric and electronic transitions and, because of the relatively long interaction length provided by strain fields in a crystal, Landau theory provides an effective formal framework for characterizing their form and magnitude. At the same time, the Debye equations provide a robust description of dynamic relaxational processes involving the mobility of defects which are coupled with strain. Improper ferroelastic transitions driven by octahedral tilting in KMnF3, LaAlO3, (Ca,Sr)TiO3, Sr(Ti,Zr)O3 and BaCeO3 are accompanied by elastic softening of tens of % and characteristic patterns of acoustic loss due to the mobility of twin walls. RUS data for ferroelectrics and ferroelectric relaxors, including BaTiO3, (K,Na)NbO3,Pb(Mg1/3Nb2/3)O3 (PMN), Pb(Sc1/2Ta1/2)O3 (PST), (Pb(Zn1/3Nb2/3)O3)0.955(PbTiO3)0.045 (PZN-PT) and (Pb(In1/2Nb1/2)O3)0.26(Pb(Mg1/3Nb2/3)O3)0.44(PbTiO3)0.30 (PIN-PMN-PT) show similar patterns of softening and attenuation but also have precursor softening associated with the development of polar nano regions. Defect-induced ferroelectricity occurs in KTaO3, without the development of long range ordering. By way of contrast, spin-lattice coupling is much more variable in strength, as reflected in a greater range of softening behaviour for Pr0.48Ca0.52MnO3 and Sm0.6Y0.4MnO3 as well as for the multiferroic perovskites EuTiO3,BiFeO3, Bi0.9Sm0.1FeO3, Bi0.9Nd0.1FeO3, (BiFeO3)0.64(CaFeO2.5)0.36, (Pb(Fe0.5Ti0.5)O3)0.4(Pb(Zr0.53Ti0.47)O3)0.6. A characteristic feature of transitions in which there is a significant Jahn-Teller component is softening as the transition point is approached from above, as illustrated by

  3. Static and dynamic strain coupling behaviour of ferroic and multiferroic perovskites from resonant ultrasound spectroscopy

    International Nuclear Information System (INIS)

    Resonant ultrasound spectroscopy (RUS) provides a window on the pervasive influence of strain coupling at phase transitions in perovskites through determination of elastic and anelastic relaxations across wide temperature intervals and with the application of external fields. In particular, large variations of elastic constants occur at structural, ferroelectric and electronic transitions and, because of the relatively long interaction length provided by strain fields in a crystal, Landau theory provides an effective formal framework for characterizing their form and magnitude. At the same time, the Debye equations provide a robust description of dynamic relaxational processes involving the mobility of defects which are coupled with strain. Improper ferroelastic transitions driven by octahedral tilting in KMnF3, LaAlO3, (Ca,Sr)TiO3, Sr(Ti,Zr)O3 and BaCeO3 are accompanied by elastic softening of tens of % and characteristic patterns of acoustic loss due to the mobility of twin walls. RUS data for ferroelectrics and ferroelectric relaxors, including BaTiO3, (K,Na)NbO3,Pb(Mg1/3Nb2/3)O3 (PMN), Pb(Sc1/2Ta1/2)O3 (PST), (Pb(Zn1/3Nb2/3)O3)0.955(PbTiO3)0.045 (PZN-PT) and (Pb(In1/2Nb1/2)O3)0.26(Pb(Mg1/3Nb2/3)O3)0.44(PbTiO3)0.30 (PIN-PMN-PT) show similar patterns of softening and attenuation but also have precursor softening associated with the development of polar nano regions. Defect-induced ferroelectricity occurs in KTaO3, without the development of long range ordering. By way of contrast, spin–lattice coupling is much more variable in strength, as reflected in a greater range of softening behaviour for Pr0.48Ca0.52MnO3 and Sm0.6Y0.4MnO3 as well as for the multiferroic perovskites EuTiO3,BiFeO3, Bi0.9Sm0.1FeO3, Bi0.9Nd0.1FeO3, (BiFeO3)0.64(CaFeO2.5)0.36, (Pb(Fe0.5Ti0.5)O3)0.4(Pb(Zr0.53Ti0.47)O3)0.6. A characteristic feature of transitions in which there is a significant Jahn–Teller component is softening as the transition point is approached from above, as illustrated

  4. Static and dynamic strain coupling behaviour of ferroic and multiferroic perovskites from resonant ultrasound spectroscopy.

    Science.gov (United States)

    Carpenter, M A

    2015-07-01

    Resonant ultrasound spectroscopy (RUS) provides a window on the pervasive influence of strain coupling at phase transitions in perovskites through determination of elastic and anelastic relaxations across wide temperature intervals and with the application of external fields. In particular, large variations of elastic constants occur at structural, ferroelectric and electronic transitions and, because of the relatively long interaction length provided by strain fields in a crystal, Landau theory provides an effective formal framework for characterizing their form and magnitude. At the same time, the Debye equations provide a robust description of dynamic relaxational processes involving the mobility of defects which are coupled with strain. Improper ferroelastic transitions driven by octahedral tilting in KMnF3, LaAlO3, (Ca,Sr)TiO3, Sr(Ti,Zr)O3 and BaCeO3 are accompanied by elastic softening of tens of % and characteristic patterns of acoustic loss due to the mobility of twin walls. RUS data for ferroelectrics and ferroelectric relaxors, including BaTiO3, (K,Na)NbO3,Pb(Mg1/3Nb2/3)O3 (PMN), Pb(Sc1/2Ta1/2)O3 (PST), (Pb(Zn1/3Nb2/3)O3)0.955(PbTiO3)0.045 (PZN-PT) and (Pb(In1/2Nb1/2)O3)0.26(Pb(Mg1/3Nb2/3)O3)0.44(PbTiO3)0.30 (PIN-PMN-PT) show similar patterns of softening and attenuation but also have precursor softening associated with the development of polar nano regions. Defect-induced ferroelectricity occurs in KTaO3, without the development of long range ordering. By way of contrast, spin-lattice coupling is much more variable in strength, as reflected in a greater range of softening behaviour for Pr0.48Ca0.52MnO3 and Sm0.6Y0.4MnO3 as well as for the multiferroic perovskites EuTiO3,BiFeO3, Bi0.9Sm0.1FeO3, Bi0.9Nd0.1FeO3, (BiFeO3)0.64(CaFeO2.5)0.36, (Pb(Fe0.5Ti0.5)O3)0.4(Pb(Zr0.53Ti0.47)O3)0.6. A characteristic feature of transitions in which there is a significant Jahn-Teller component is softening as the transition point is approached from above, as illustrated by

  5. Imaging of coherent magneto-elastic domains in multiferroic BiFeO3 films

    OpenAIRE

    Price, N. Waterfield; Johnson, R. D.; Saenrang, W.; Maccherozzi, F; Dhesi, S.S.; Bombardi, A.; Chmiel, F. P.; Eom, C. -B.; Radaelli, P. G.

    2015-01-01

    A current challenge presented in thin film physics is imaging and controlling antiferromagnetic domains at the nanoscale. By employing a combination of non-resonant x-ray magnetic scattering, neutron diffraction and vector-mapped x-ray magnetic linear dichroism photoemission electron microscopy, we have directly visualised the sub-micron scale antiferromagnetic domain structure of epitaxial (111) BiFeO3 films. We find that these domains are coherently coupled to crystallographic domain struct...

  6. Pyrolyzed thin film carbon

    Science.gov (United States)

    Tai, Yu-Chong (Inventor); Liger, Matthieu (Inventor); Harder, Theodore (Inventor); Konishi, Satoshi (Inventor); Miserendino, Scott (Inventor)

    2010-01-01

    A method of making carbon thin films comprises depositing a catalyst on a substrate, depositing a hydrocarbon in contact with the catalyst and pyrolyzing the hydrocarbon. A method of controlling a carbon thin film density comprises etching a cavity into a substrate, depositing a hydrocarbon into the cavity, and pyrolyzing the hydrocarbon while in the cavity to form a carbon thin film. Controlling a carbon thin film density is achieved by changing the volume of the cavity. Methods of making carbon containing patterned structures are also provided. Carbon thin films and carbon containing patterned structures can be used in NEMS, MEMS, liquid chromatography, and sensor devices.

  7. Thin film processes II

    CERN Document Server

    Kern, Werner

    1991-01-01

    This sequel to the 1978 classic, Thin Film Processes, gives a clear, practical exposition of important thin film deposition and etching processes that have not yet been adequately reviewed. It discusses selected processes in tutorial overviews with implementation guide lines and an introduction to the literature. Though edited to stand alone, when taken together, Thin Film Processes II and its predecessor present a thorough grounding in modern thin film techniques.Key Features* Provides an all-new sequel to the 1978 classic, Thin Film Processes* Introduces new topics, and sever

  8. Room temperature ferroelectric and magnetic investigations and detailed phase analysis of Aurivillius phase Bi5Ti3Fe0.7Co0.3O15 thin films

    International Nuclear Information System (INIS)

    Aurivillius phase Bi5Ti3Fe0.7Co0.3O15 (BTF7C3O) thin films on α-quartz substrates were fabricated by a chemical solution deposition method and the room temperature ferroelectric and magnetic properties of this candidate multiferroic were compared with those of thin films of Mn3+ substituted, Bi5Ti3Fe0.7Mn0.3O15 (BTF7M3O). Vertical and lateral piezoresponse force microscopy (PFM) measurements of the films conclusively demonstrate that BTF7C3O and BTF7M3O thin films are piezoelectric and ferroelectric at room temperature, with the major polarization vector in the lateral plane of the films. No net magnetization was observed for the in-plane superconducting quantum interference device (SQUID) magnetometry measurements of BTF7M3O thin films. In contrast, SQUID measurements of the BTF7C3O films clearly demonstrated ferromagnetic behavior, with a remanent magnetization, Br, of 6.37 emu/cm3 (or 804 memu/g), remanent moment = 4.99 × 10-5 emu. The BTF7C3O films were scrutinized by x-ray diffraction, high resolution transmission electron microscopy, scanning transmission electron microscopy, and energy dispersive x-ray analysis mapping to assess the prospect of the observed multiferroic properties being intrinsic to the main phase. The results of extensive micro-structural phase analysis demonstrated that the BTF7C3O films comprised of a 3.95% Fe/Co-rich spinel phase, likely CoFe2-xTixO4, which would account for the observed magnetic moment in the films. Additionally, x-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM) imaging confirmed that the majority of magnetic response arises from the Fe sites of Fe/Co-rich spinel phase inclusions. While the magnetic contribution from the main phase could not be determined by the XMCD-PEEM images, these data however imply that the Bi5Ti3Fe0.7Co0.3O15 thin films are likely not single phase multiferroics at room temperature. The PFM results presented demonstrate that the naturally 2D nanostructured Bi5Ti3Fe0

  9. Direct band gaps in multiferroic h-LuFeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Holinsworth, B. S.; Mazumdar, D.; Musfeldt, J. L. [Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996 (United States); Brooks, C. M. [Department of Material Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Mundy, J. A.; Das, H.; Fennie, C. J. [School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853 (United States); Cherian, J. G. [Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996 (United States); National High Magnetic Field Laboratory, Tallahassee, Florida 32310 (United States); McGill, S. A. [National High Magnetic Field Laboratory, Tallahassee, Florida 32310 (United States); Schlom, D. G. [Department of Material Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States)

    2015-02-23

    We measured the optical properties of epitaxial thin films of the metastable hexagonal polymorph of LuFeO{sub 3} by absorption spectroscopy, magnetic circular dichroism, and photoconductivity. Comparison with complementary electronic structure calculations reveals a 1.1 eV direct gap involving hybridized Fe 3d{sub z{sup 2}}+O 2p{sub z}→Fe d excitations at the Γ and A points, with a higher energy direct gap at 2.0 eV. Both charge gaps nicely overlap the solar spectrum.

  10. Effects of magnetic annealing on structure and multiferroic properties of pure and dysprosium substituted BiFeO 3

    KAUST Repository

    Zhang, Shuxia

    2012-07-01

    In this work, the effects of magnetic annealing on crystal structure and multiferroic properties of BiFeO 3 and Bi 0.85Dy 0.15FeO 3 have been investigated. It is found that the X-ray diffraction patterns of pure BiFeO 3 samples are obviously broadened after magnetic annealing, whereas those of Bi 0.85Dy 0.15FeO 3 samples are almost unchanged. Magnetic field annealing did not affect the magnetic properties of these two kinds of samples much. However, ferroelectric properties of the two materials exhibited different behaviors after magnetic field annealing. For pure BiFeO 3 samples, the remnant polarizations (P r) are suppressed; in contrast, for Bi 0.85Dy 0.15FeO 3 samples, P r is greatly enhanced. Possible mechanisms for the effects of magnetic field annealing have been discussed. © 2012 Elsevier B.V. All rights reserved.

  11. Low temperature magnetic studies on PbFe0.5Nb0.5O3 multiferroic

    International Nuclear Information System (INIS)

    PbFe0.5Nb0.5O3 (PFN), a well-known A(B′1/2B″1/2)O3 type multiferroic, was successfully synthesized in single phase by a single step solid state reaction method. The single phase PFN was characterized through XRD, microstructure through SEM, and magnetic studies were carried out through a temperature dependent vibrating sample magnetometer (VSM) and neutron diffraction (ND) measurements. PFN exhibits a cusp at around 150 K in the temperature dependent magnetic susceptibility corresponding to the Néel temperature (TN1) and another peak around 10 K (TN2) corresponding to spin-glass like transition. In the temperature dependent ND studies, a magnetic Bragg peak appears at Q=1.35 Å−1 (where Q=4πsinθ/λ, is called the scattering vector) below TN (150 K) implying antiferromagnetic (AFM) ordering in the system. On the basis of Rietveld analysis of the ND data at T=2 K, the magnetic structure of PFN could be explained by a G-type antiferromagnetic structure

  12. Disorder-driven spin-reorientation in multiferroic h-YMn1−xFexO3

    International Nuclear Information System (INIS)

    Magnetic structure evolution of multiferroic hexagonal YMn1−xFexO3 (x = 0, 0.05, and 0.1) has been studied by carrying out detailed temperature-dependent neutron diffraction at zero and 5 T fields. Thermodynamic data confirm antiferromagnetic ordering at TN in all the compositions. Our sub-TN neutron diffraction results assign the magnetic structure of pure YMnO3 to Γ1 irreducible representation. Over the perturbative-doping range, magnetic structure changes via Γ1 + Γ2 for YMn0.95Fe0.05O3 on to Γ2 for YMn0.9Fe0.1O3, as the maiden compositional analogue of spin-reorientation; its occurrence in temperature-domain already reported for several manganites. Moreover, while the large thermal isostructural changes observed above TN are subdued in the ordered state, small alterations by the applied 5 T-field are relatively uniform across, confirming strong magneto-elastic nature of the system. Decrease of the ordered magnetic moment (μord) and planar magnetic frustration noted with Fe-doping is enhanced by the applied field, apparently through canting.

  13. Elastic anomaly and order-disorder nature of multiferroic barium sodium niobate studied by broadband brillouin scattering

    International Nuclear Information System (INIS)

    The successive phase transitions of multiferroic barium sodium niobate, Ba2NaNb5O15 (BNN), were studied by Brillouin scattering. The LA, TA modes, and central peak were measured in a large temperature range from room temperature up to 750 °C. In the vicinity of a ferroelectric phase transition at about TC = 585 °C from the prototypic tetragonal 4/mmm to ferroelectric 4mm phases, elastic anomaly was observed for LA and TA modes. In addition, the order-disorder nature was observed by the temperature dependence of a central peak. For further cooling another elastic anomaly was also observed in the vicinity of a ferroelastic incommensurate phase transition at about TIC = 285 °C into orthorhombic 2mm phase with the appearance of incommensurate modulation. The large thermal hysteresis of elastic anomaly near TIC can be attributed the typical feature of the type III incommensurate phase transition predicted recently by Ishibashi and Iwata (2013 J. Phys. Soc. Jpn. 82 044703)

  14. Probing ferroic transitions in a multiferroic framework family: a neutron diffraction study of the ammonium transition metal formates.

    Science.gov (United States)

    Lawler, James M M; Manuel, Pascal; Thompson, Amber L; Saines, Paul J

    2015-07-01

    This study probes the magnetic and ferroelectric ordering of the NH4M(HCO2)3 (M = Mn(2+), Fe(2+), Co(2+) and Ni(2+)) frameworks using neutron diffraction, improving the understanding of the origins of the properties of these fascinating multiferroics. This rare study of the magnetic structure of a family of metal-organic frameworks shows that all four compounds exhibit antiferromagnetic coupling between neighbouring cations bridged by formate ligands. The orientation of the spin, however, changes in a highly unusual way across the series with the spins aligned along the c-axis for the Fe(2+) and Ni(2+) frameworks but lying in the ab plane for the other members of the series. This work also sheds new light on the nature of the ferroelectric order-disorder transition in these materials; probing changes in the ammonium cation across the transition and also shows that the Ni(2+) framework does not undergo a transition to the polar P63 phase due to the smaller size of the Ni(2+) cation. Finally trends in their anisotropic negative thermal expansion, which potentially enhances their ferroic behaviour, are quantified. PMID:26040906

  15. Giant electric field tunable magnetic properties in a Co50Fe50/lead magnesium niobate-lead titanate multiferroic heterostructure

    Science.gov (United States)

    Yang, Wei-Gang; Morley, Nicola A.; Sharp, Joanne; Rainforth, W. Mark

    2015-08-01

    Co50Fe50/(0 1 1)-oriented lead magnesium niobate-lead titanate (PMN-PT) multiferroic (MF) heterostructures were fabricated by RF sputtering magnetic films onto PMN-PT substrates. The effect of magnetic layer thickness (30 nm to 100 nm) on the magnetoelectric (ME) coupling in the heterostructures was studied independently, due to the almost constant magnetostriction constant (λ = 40   ±   5 ppm) and similar as-grown magnetic anisotropies for all studied magnetic layer thicknesses. A record high remanence ratio (M r/M s) tunability of 95% has been demonstrated in the 65 nm Co50Fe50/PMN-PT heterostructure, corresponding to a large ME constant (α) of 2.5   ×   10-6 s m-1, when an external electric field (E-field) of 9 kV cm-1 was applied. Such an MF heterostructure provides considerable opportunities for E-field-controlled multifunctional devices.

  16. Gadolinium substitution induced defect restructuring in multiferroic BiFeO3: case study by positron annihilation spectroscopy

    International Nuclear Information System (INIS)

    Positron annihilation spectroscopy (PAS) comprising of the measurements of positron lifetime and coincidence Doppler broadening spectra has been carried out to understand and monitor the evolution of the vacancy-type defects arising from the ionic deficiencies at lattice points of the multiferroic perovskite bismuth ferrite (BiFeO3) doped with 1, 5 and 10 at% gadolinium (Gd3+) ions. Negatively charged defects in the form of Bi3+ monovacancies (VBi3−) were present in the undoped nanocrystallites, which strongly trapped positrons. During the successive doping by Gd3+ ions, the positron trapping efficiency decreased while the doped ions combined with the vacancies to form complexes, which became neutral. A fraction of the positrons got annihilated at the crystallite surfaces too, being evident from the very large positron lifetimes obtained and confirming the nano-size-specific characteristics of the samples. Further, the intercrystallite regions provided favourable sites for orthopositronium formation, although in minute concentrations. The dopant ion-complex formation was also depicted clearly by the defect characteristic S–W plot. Also, the large change of electrical resistivity with Gd concentration has been explained nicely by invoking the defect information from the PAS study. The study has demonstrated the usefulness of an excellent method of defect identification in such a novel material system, which is vital information for exploiting them for further technological applications. (paper)

  17. Electric field-induced magnetoresistance in spin-valve/piezoelectric multiferroic laminates for low-power spintronics

    International Nuclear Information System (INIS)

    Electric field-induced magnetic anisotropy has been realized in the spin-valve-based {Ni80Fe20/Cu/Fe50Co50/IrMn}/piezoelectric multiferroic laminates. In this system, electric-field control of magnetization is accomplished by strain mediated magnetoelectric coupling. Practically, the magnetization in the magnetostrictive FeCo layer of the spin-valve structure rotates under an effective compressive stress caused by the inverse piezoelectric effect in external electrical fields. This phenomenon is evidenced by the magnetization and magnetoresistance changes under the electrical field applied across the piezoelectric layer. The result shows great potential for advanced low-power spintronic devices. - Highlights: ► Investigate electric field-induced magnetic anisotropy in spin-valve/piezoelectric. ► Magnetization, magnetoresistance changes under electric field across piezoelectric. ► Magnetization in magnetostrictive FeCo-layer rotates under a compressive stress. ► This advance shows great implications for low-power electronics and spintronics.

  18. Equilibrium phases in the multiferroic BiFeO3-PbTiO3 system – a revisit

    Directory of Open Access Journals (Sweden)

    Kothai V.

    2014-07-01

    Full Text Available The(1-x BiFeO3-(x PbTiO3 solid solution exhibiting a Morphotropic Phase Boundary (MPB has attracted considerable attention recently because of its unique features such as multiferroic, high Curie point (TC ~ 700°C and giant tetragonality (c/a -1 ~ 0.19. Different research groups have reported different composition range of MPB for this system. In this work we have conclusively proved that the wide composition range of MPB reported in the literature is due to kinetic arrest of the metastable rhombohedral phase and that if sufficient temperature and time is allowed the metastable phase disappears. The genuine MPB was found to be x=0.27 for which the tetragonal and the rhombohedral phases are in thermodynamic equilibrium. In-situ high temperature structural study of x=0.27 revealed the sluggish kinetics associated with the temperature induced structural transformation. Neutron powder diffraction study revealed that themagnetic ordering at room temperature occurs in the rhombohedral phase. The magnetic structure was found to be commensurate G-type antiferromagnetic with magnetic moments parallel to the c-direction (of the hexagonal cell. The present study suggests that the equilibrium properties in this solid solution series should be sought for x=0.27.

  19. Modified Heisenberg model for the zig-zag structure in multiferroic RMn{sub 2}O{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Bahoosh, Safa Golrokh, E-mail: safa.bahoosh@uni-konstanz.de [Department of Physics, University of Konstanz, D-78457 Konstanz (Germany); Wesselinowa, Julia M., E-mail: julia@phys.uni-sofia.bg [Department of Physics, University of Sofia, 1164 Sofia (Bulgaria); Trimper, Steffen, E-mail: steffen.trimper@physik.uni-halle.de [Institute of Physics, Martin-Luther-University Halle-Wittenberg, D-06099 Halle (Germany)

    2015-08-28

    The class of RMn{sub 2}O{sub 5} (R = Ho, Tb, Y, Eu) compounds offers multiferroic properties where the refined magnetic zig-zag order breaks the inversion symmetry. Varying the temperature, the system undergoes a magnetic and a subsequent ferroelectric phase transition where the ferroelectricity is magnetically induced. We propose a modified anisotropic Heisenberg model that can be used as a tractable analytical model studying the properties of those antiferromagnetic zig-zag spin chains. Based on a finite temperature Green's function method, it is shown that the polarization is induced solely by different exchange couplings of the two different Mn{sup 4+} and Mn{sup 3+} magnetic ions. We calculate the excitation energy of the spin system for finite temperatures, which for its part determines the temperature dependent magnetization and polarization. The ferroelectric phase transition is manifested as a kink in the excitation energy. The variation of the polarization by an external magnetic field depends strongly on the direction of that field. Whereas, the polarization in b-direction increases with an external magnetic field as well in b-direction it can be switched for strong fields in a-direction. The results based on that modified Heisenberg model are in qualitative agreement with experimental data.

  20. Multiferroic properties of Bi0.8Dy0.2-xLaxFeO3 nanoparticles

    International Nuclear Information System (INIS)

    Bi0.8Dy0.2-xLaxFeO3 (BDLFOx) (x = 0, 0.10 and 0.20 respectively) nanoparticles were prepared by the ethylene glycol based sol-gel method. The influence of the average radius and the effective magnetic moment of Bi-site ion on the structure, magnetic and dielectric properties, and the effective magnetic susceptibility of BDLFOx nanoparticles was investigated. All the samples were indexed to the orthorhombic structure based on the results of x-ray diffraction. The grain size of the samples increased with the increase in Bi-site ionic average radius. The magnetization of the samples was found to decrease with the effective magnetic moment of Bi-site ion decreasing. The dielectric constant and loss were improved when the Bi-site ionic average radius decreased and the effective magnetic moment of the Bi-site ions increased. The enhanced magnetization M and the polarization P in nanoparticles made the effective magnetic susceptibility of the samples greatly enhanced, in particular for the sample of x = 0. Therefore we concluded that the small amount of substitution of Bi3+ ions by trivalent rare-earth ions with a smaller ionic radius than Bi3+ ion and a high magnetic moment in the nano-system was a way to improve the multiferroic properties of BiFeO3.

  1. Enhanced dielectric and ferroelectric properties of Ba and Ti co-doped BiFeO3 multiferroic ceramics

    International Nuclear Information System (INIS)

    Highlights: • The structural phase transition with increasing Ti content was confirmed. • The reduction of low frequency dispersion in dielectric constant with Ti content. • With increasing Ti content the ferroelectricity was gradually improved. • Variation of the ferroelectric hysteresis loop induced by magnetic polarization. -- Abstract: Multiferroic ceramics Bi0.8Ba0.2Fe1−xTixO3 with x = 0, 0.1 and 0.2 were prepared by using the conventional solid state reaction method. The structural, dielectric, ferroelectric and magnetic properties were investigated. The structure phase transition from rhombohedral to tetragonal with increasing the Ti substitution concentration was confirmed using X-ray diffraction. The reduction of low frequency dispersion in the dielectric constant and loss with an increase in the Ti content was observed. The ferroelectric measurements revealed that the leakage current is significantly suppressed with Ti substitution. Magnetic hysteresis loops showed a continuous decrease in magnetization with Ti substitution, which can be attributed to the collinear antiferromagnetic spin structure in tetragonal structure. In addition, a remarkable change in the polarization and ferroelectric loop area after poling the samples in the dc magnetic field indicates the presence of magnetoelectric coupling at room temperature

  2. Effect of oxygen partial pressure on the magnetic properties of YMnO3 thin films

    International Nuclear Information System (INIS)

    Hexagonal YMnO3 (YMO) is one of the extensively studied multiferroic material over the last few years due to its coupled ferroelectric and magnetic behavior at low temperature. Its magnetic properties display a strong dependence on concentration of manganese and oxygen in bulk form of YMO. There are few reports in literature which point out importance of deposition conditions like substrate temperature, oxygen partial (OPP) etc. during film preparation. Hexagonal/orthorhombic YMnO3 or YMn2O5 films can be formed by using different deposition parameters. All these factors can modify magnetic properties of YMO film. It is believed that variation in OPP influences the Mn content. Here, we examine magnetic properties of pulsed laser deposited YMO thin films prepared on Al2O3 (0001) substrate in different OPP when all other deposition were kept similar. The films prepared in vacuum reveal a typical anti-ferromagnetic transition of bulk YMnO3, while the films prepared at 1x10-4 Torr OPP behave similar to Mn rich YMnO3 with a metastable magnetic state below 42 K temperature. Further, the Mn rich YMnO3 thin film sample reveals exchange bias phenomenon at 5 K temperature. (author)

  3. Modulation of physical properties of oxide thin films by multiple fields

    Science.gov (United States)

    Hua-Li, Yang; Bao-Min, Wang; Xiao-Jian, Zhu; Jie, Shang; Bin, Chen; Run-Wei, Li

    2016-06-01

    Recent studies of the modulation of physical properties in oxide thin films by multiple fields are reviewed. Some of the key issues and prospects of this area of study are also addressed. Oxide thin films exhibit versatile physical properties such as magnetism, ferroelectricity, piezoelectricity, metal–insulator transition (MIT), multiferroicity, colossal magnetoresistivity, switchable resistivity. More importantly, the exhibited multifunctionality can be tuned by various external fields, which has enabled demonstration of novel electronic devices. Project supported by the State Key Project of Fundamental Research of China (Grant No. 2012CB933004), the National Natural Science Foundation of China (Grant Nos. 11474295, 51571208, 51525103, and 11274322), Overseas, Hong Kong & Macao Scholars Collaborated Researching Fund (Grant No. 51428201), the Instrument Developing Project of the Chinese Academy of Sciences (Grant No. YZ201327), Ningbo Major Project for Science and Technology (Grant No. 2014B11011), Ningbo International Cooperation Projects (Grant Nos. 2012D10018 and 2014D10005), the Fund for Ningbo Science and Technology Innovation Team (Grant No. 2015B11001), the Youth Innovation Promotion Association of the Chinese Academy of Sciences, and the Key Research Program of the Chinese Academy of Sciences (Grant No. KJZD-EW-M05).

  4. Elastic and magnetoelastic relaxation behaviour of multiferroic (ferromagnetic + ferroelectric + ferroelastic) Pb(Fe_0.5Nb_0.5)O_3 perovskite

    OpenAIRE

    Carpenter, M A; Schiemer, J. A.; Lascu, I; Harrison, R J; Kumar, A; Katiyar, R. S.; Ortega, N.; Sanchez, D. A.; Salazar Mejia, C.; Schnelle, W.; Echizen, M.; Shinohara, H; Heap, A. J. F.; Nagaratnam, R.; Dutton, S. E.

    2015-01-01

    Resonant Ultrasound Spectroscopy has been used to characterise elastic and anelastic anomalies in a polycrystalline sample of multiferroic Pb(Fe_0.5Nb_0.5)O_3 (PFN). Elastic softening begins at ~550 K, which is close to the Burns temperature marking the development of dynamical polar nanoregions. A small increase in acoustic loss at ~425 K coincides with the value of T* reported for polar nanoregions starting to acquire a static or quasistatic component. Softening of the shear modulus by ~30-...

  5. High-resolution structure studies and magnetoelectric coupling of relaxor multiferroic Pb(Fe$_{0.5}$Nb$_{0.5}$)O$_3$

    OpenAIRE

    Sim, Hasung; Darren C. Peets; Lee, Sanghyun; Lee, Seongsu; Kamiyama, T.; Ikeda, K.; Otomo, T; Cheong, S.-W.; Park, Je-Geun

    2015-01-01

    Pb(Fe$_{0.5}$Nb$_{0.5}$)O$_3$ (PFN), one of the few relaxor multiferroic systems, has a $G$-type antiferromagnetic transition at $T_N$ = 143 K and a ferroelectric transition at $T_C$ = 385 K. By using high-resolution neutron-diffraction experiments and a total scattering technique, we paint a comprehensive picture of the long- and short-range structures of PFN: (i) a clear sign of short-range structural correlation above $T_C$, (ii) no sign of the negative thermal expansion behavior reported ...

  6. Neutron Diffraction Studies on Chemical and Magnetic Structure of Multiferroic PbFe0.67W0.33O3

    OpenAIRE

    Matteppanavar, Shidaling; Angadi, Basavaraj; Rayapro, Sudhindra

    2015-01-01

    We report on the single phase synthesis and room temperature structural characterization of PbFe0.67W0.33O3 (PFW) multiferroic. The PFW was synthesized by low temperature sintering, Columbite method. Analysis of powder XRD pattern exhibits single phase formation of PFW with no traces of pyrochlore phase. Detailed analysis of room temperature neutron diffraction (ND) reveals cubic phase at room temperature, space group Pm-3m. The ND pattern clearly reveals magnetic Bragg peak at 2theeta = 18.5...

  7. Tuning ferroic states in La doped BiFeO{sub 3}-PbTiO{sub 3} displacive multiferroic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Cótica, L. F., E-mail: lfcotica@dfi.uem.br [Department of Electrical and Computer Engineering, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249 (United States); Department of Physics, State University of Maringá, Maringá, PR 87020-900 (Brazil); Freitas, V. F.; Protzek, O. A. [Department of Physics, State University of Maringá, Maringá, PR 87020-900 (Brazil); Eiras, J. A.; Garcia, D. [Department of Physics, Federal University of São Carlos, São Carlos, SP 13565-905 (Brazil); Yokaichiya, F.; Santos, I. A. [Nuclear and Energy Research Institute, São Paulo, SP 05508-000 (Brazil); Guo, R.; Bhalla, A. S. [Department of Electrical and Computer Engineering, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249 (United States)

    2014-07-21

    In this manuscript, X-ray and high-resolution neutron powder diffraction investigations, associated with Rietveld refinements, magnetic hysteresis curves and a modeling of electron-density distributions around the ions, are used to describe the driving forces responsible for tuning the ferroic states in La doped (0.6)BiFeO{sub 3}-(0.4)PbTiO{sub 3} compositions. The intrinsic relations between the ferroic orders and the structural arrangements (angles, distances and electron-density distributions around the ions) are revealed, helping in the understanding of some aspects comprising the ferroic properties of perovskite-based displacive multiferroic compounds.

  8. On the theory of stress-magnetic field phase diagram of the finite size multiferroics: competition between ferro- and antiferromagnetic domains

    International Nuclear Information System (INIS)

    We analyze the behavior of multiferroics with antiferro-(AFM) and ferromagnetic (FM) ordering under the action of external magnetic and stress fields. A combination of these two fields makes it possible to achieve macroscopic states with different domain structures. The two-domain state obtained in this way shows a linear dependence of macroscopic strain vs magnetic field which is unusual for AFMs. A small but nonzero stress applied to the sample can also result in the bias of the magnetization vs magnetic field dependence.

  9. Magnetically induced electric polarization reversal in multiferroic TbMn$_2$O$_5$: Terbium spin reorientation studied by resonant x-ray diffraction

    OpenAIRE

    Johnson, R. D.; Mazzoli, C.; Bland, S. R.; Du, C-H.; Hatton, P. D.

    2011-01-01

    In multiferroic TbMn$_2$O$_5$, the behavior of the terbium ions forms a crucial part of the magneto-electric coupling. The result is a magnetically induced reversal of the electric polarization at 2 T. In this article we present the first direct measurement of the terbium magnetic structure under applied magnetic fields. Contrary to the current interpretation of the magnetic properties of \\tmo, we show that upon the electric polarization reversal the terbium sub-lattice adopts a canted antife...

  10. Magnetic, ferroelectric and leakage current properties of gadolinium doped bismuth ferrite thin films by sol–gel method

    International Nuclear Information System (INIS)

    Bi0.9Gd0.1FeO3 (BGFO) thin films were fabricated on Pt(111)/Ti/SiO2/Si(100) substrates by using the sol–gel technology. The effects of annealing temperature (400–700 °C) on microstructure and multiferroic properties of thin films were investigated. The X-ray diffraction analysis showed that the BGFO thin films had an orthorhombic structure. The thin films showed ferroelectric and ferromagnetic properties with remanent polarization (2Pr) of 10 μC/cm2, remnant magnetization (2Mr) of 2.4 emu/g and saturation magnetization (Ms) of 5.3 emu/g. A small leakage current density (J) was 4.64×10−8 A/cm2 under applied field 100 kV/cm. It was found that more than one conduction mechanism is involved in the electric field range used in these experiments. The leakage current mechanisms were controlled by Poole–Frenkel emission in the low electric field region and by Schottky emission from the Pt electrode in the high field region. - Highlights: • Bi3.96Pr0.04Ti2.95Nb0.05O12 thin films were prepared by sol–gel technology. • Thin films showed 2Pr of 10 μC/cm2, 2Mr of 2.4 emu/g and Ms of 5.3 emu/g. • Leakage current mechanisms were controlled by Poole–Frenkel and Schottky emission

  11. Polarization enhancement and ferroelectric switching enabled by interacting magnetic structures in DyMnO3 thin films

    KAUST Repository

    Lu, Chengliang

    2013-12-02

    The mutual controls of ferroelectricity and magnetism are stepping towards practical applications proposed for quite a few promising devices in which multiferroic thin films are involved. Although ferroelectricity stemming from specific spiral spin ordering has been reported in highly distorted bulk perovskite manganites, the existence of magnetically induced ferroelectricity in the corresponding thin films remains an unresolved issue, which unfortunately halts this step. In this work, we report magnetically induced electric polarization and its remarkable response to magnetic field (an enhancement of ?800% upon a field of 2 Tesla at 2 K) in DyMnO3 thin films grown on Nb-SrTiO3 substrates. Accompanying with the large polarization enhancement, the ferroelectric coercivity corresponding to the magnetic chirality switching field is significantly increased. A picture based on coupled multicomponent magnetic structures is proposed to understand these features. Moreover, different magnetic anisotropy related to strain-suppressed GdFeO 3-type distortion and Jahn-Teller effect is identified in the films.

  12. Pulsed laser deposition of La1−xSrxMnO3: thin-film properties and spintronic applications

    International Nuclear Information System (INIS)

    Materials engineering on the nanoscale by precise control of growth parameters can lead to many unusual and fascinating physical properties. The development of pulsed laser deposition (PLD) 25 years ago has enabled atomistic control of thin films and interfaces and as such it has contributed significantly to advances in fundamental material science. One application area is the research field of spintronics, which requires optimized nanomaterials for the generation and transport of spin-polarized carriers. The mixed-valence manganite La1−xSrxMnO3 (LSMO) is an interesting material for spintronics due to its intrinsic magnetoresistance properties, electric-field tunable metal–insulator transitions, and half-metallic band structure. Studies on LSMO thin-film growth by PLD show that the deposition temperature, oxygen pressure, laser fluence, strain due to substrate–film lattice mismatch and post-deposition annealing conditions significantly influence the magnetic and electrical transport properties of LSMO. For spintronic structures, robust ferromagnetic exchange interactions and metallic conductivity are desirable properties. In this paper, we review the physics of LSMO thin films and the important role that PLD played in advancing the field of LSMO-based spintronics. Some specific application areas including magnetic tunnel junctions, multiferroic tunnel junctions and organic spintronic devices are highlighted, and the advantages, drawbacks and opportunities of PLD-grown LSMO for next-generation spintronic devices are discussed. (paper)

  13. Ferroelectric and electrical characterization of multiferroic BiFeO3 at the single nanoparticle level

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, Rama K [ORNL; Bogle, K A [University of New South Wales, Sydney, Australia; Kumar, Amit [ORNL; Jesse, Stephen [ORNL; Magaraggia, R [University of Glasgow; Stamps, R [University of Glasgow; Ogale, S [National Chemical Laboratory, India; Potdar, H S [National Chemical Laboratory, India

    2011-01-01

    Ferroelectric BiFeO3 (BFO) nanoparticles deposited on epitaxial substrates of SrRuO3 (SRO) and La1xSrxMnO3 (LSMO) were studied using band excitation piezoresponse spectroscopy (BEPS), piezoresponse force microscopy (PFM), and ferromagnetic resonance (FMR). BEPS confirms that the nanoparticles are ferroelectric in nature. Switching behavior of nanoparticle clusters were studied and showed evidence for inhomogeneous switching. The dimensionality of domains within nanoparticles was found to be fractal in nature, with a dimensionality constant of 1.4, on par with ferroelectric BFO thin-films under 100 nm in thickness. Ferromagnetic resonance studies indicate BFO nanoparticles only weakly affect the magnetic response of LSMO.

  14. Visualization and manipulation of meta-stable polarization variants in multiferroic materials

    Directory of Open Access Journals (Sweden)

    Moonkyu Park

    2013-04-01

    Full Text Available Here we demonstrate the role of meta-stable polarization variants in out-of-plane polarization switching behavior in epitaxially grown BiFeO3 thin films using angle-resolved piezoresponse force microscopy (AR-PFM. The out-of-plane polarization switching mainly occurred at the boundary between meta-stable and stable polarization domains, and was accompanied by a significant change in in-plane domain configuration from complicated structure with 12 polarization variants to simple stripe structure with 4 polarization variants. These results imply that the biased tip rearranges the delicately balanced domain configuration, which is determined by the competition between electrostatic and strain energies, into simple interweaving one that is more thermodynamically stable.

  15. Superspin glass phase and hierarchy of interactions in multiferroic PbFe.sub.1/2./sub.Sb.sub.1/2./sub.O.sub.3./sub.: an analog of ferroelectric relaxors?

    Czech Academy of Sciences Publication Activity Database

    Laguta, Valentyn; Stephanovich, V. A.; Savinov, Maxim; Maryško, Miroslav; Kuzian, R. O.; Kondakova, I.V.; Olekhnovich, N.M.; Pushkarev, A.V.; Radyush, Yu.V.; Raevski, I. P.; Raevskaya, S. I.; Prosandeev, S. A.

    2014-01-01

    Roč. 16, Nov (2014), "113041-1"-"113041-19". ISSN 1367-2630 R&D Projects: GA ČR GA13-11473S Institutional support: RVO:68378271 Keywords : multiferroics * spin glass * superantiferromagnetism * ferroelectrics * relaxors Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.558, year: 2014

  16. Magnetoelastic coupling in multiferroic GdMnO3 and metamagnetic Ca2-xSrxRuO4

    International Nuclear Information System (INIS)

    Subject of the present thesis is the magnetoelastic coupling in multiferroic GdMnO3 and the metamagnetic Ca2-xSrxRuO4 with x between 0.2 and 0.5. GdMnO3 belongs to a class of new multiferroic materials where ferroelectricity shows up inside a magnetically ordered phase and a strong coupling between the magnetic and the electric properties is present. It possesses two magnetic transitions, one at TN into the ICAFM phase and one at Tc into the cAFM phase. Furthermore, for H parallel b, a ferroelectric transition occurs at TFE. Based on thermal-expansion and magnetostriction data, a modified H-T-phase diagram is derived. Due to large hysteresis effects in the low-field and low-temperature region, the pure cAFM phase cannot be reached upon cooling in zero magnetic field. The transition into the cAFM phase is accompanied by a jumplike drop of the orthorhombic splitting, which recovers upon entering the ferroelectric phase. Moreover, the uniaxial pressure dependencies of all three transitions are analysed. For the compound Ca2-xSrxRuO4 a change of the relevant magnetic correlation from ferromagnetic to antiferromagnetic is observed as soon as the RuO6 octahedra start tilting upon decreasing the Sr content below x=0.5. In Ca1.8Sr0.2RuO4, a metamagnetic transition occurs in a magnetic field, which comes along with strong structural changes. However, a complete suppression of the tilt upon the magnetic-field induced crossover from antiferromagnetic to ferromagnetic correlations can be excluded. At low temperatures, strong and anisotropic thermal expansion anomalies are observed. Both, these anomalies and the structural changes at the metamagnetic transition point towards a rearrangement of the orbital occupation induced by temperature as well as by magnetic field. For Ca1.8Sr0.2RuO4, a sign change of the low-temperature anomalies of the thermal expansion and the strong increase of the Grueneisen parameter in fields close to the metamagnetic transition can be identified as

  17. Effect of rare earth substitution on properties of barium strontium titanate ceramic and its multiferroic composite with nickel cobalt ferrite

    International Nuclear Information System (INIS)

    Highlights: • Rare earth ions Dy3+, Gd3+ and Sm3+ have been substituted in Ba0.95Sr0.05TiO3 (BST). • Ni0.8Co0.2Fe2O4 has been used as ferrimagnetic phase to obtain composites. • Substitution of these ions increases dielectric constant of BST and composites. • Magnetoelectric coefficient of composites increases on substitution of these ions. - Abstract: Effect of substitution of rare earth ions (Dy3+, Gd3+ and Sm3+) on various properties of Ba0.95Sr0.05TiO3 (BST) i.e. the composition Ba0.95−1.5xSr0.05RxTiO3 (where x = 0.00, 0.01, 0.02, 0.03 and R are rare earths Dy, Gd, Sm) and that of their multiferroic composite with Ni0.8Co0.2Fe2O4 (NCF) has been studied. Shifting of peaks corresponding to different compositions in the X-ray diffraction pattern confirmed the substitution of rare earth ions at both Ba2+ and Ti4+ sites in BST. It is clear from scanning electron microscopy (SEM) images that rare earth substitution in BST increases its grain size in both pure and composite samples. Substitution of rare earth ions results in increase in value of dielectric constant of pure and composite samples. Sm substitution in BST significantly decreases its Curie temperature. Dy substituted pure and composite samples possess superior ferroelectric properties as confirmed by polarization vs electric field (P–E) loops. Composite samples containing Dy, Gd and Sm substituted BST as ferroelectric phase possess lower values of remanent and saturation magnetizations in comparison to composite sample containing pure BST as ferroelectric phase (BSTC). Rare earth substituted composite samples possess higher value of magnetoelectric coefficient as compared to that for BSTC

  18. Structural, electrical, magnetic and {sup 57}Fe Mössbauer study of polycrystalline multiferroic DyFeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, S. Shravan Kumar; Raju, N. [Department of Physics, Osmania University, Hyderabad 500007, Telangana (India); Reddy, Ch. Gopal, E-mail: ch_gopalreddy@yahoo.com [Department of Physics, University College of Engineering, Osmania University, Hyderabad 500007, Telangana (India); Reddy, P. Yadagiri; Reddy, K. Rama [Department of Physics, Osmania University, Hyderabad 500007, Telangana (India); Reddy, V. Raghavendra [UGC DAE Consortium for Scientific Research, University campus, Khandwa Road, Indore, Madhya Pradesh 452001 (India)

    2015-12-15

    Structural, Raman spectroscopy, leakage current density, temperature dependent magnetization and Mössbauer measurements of polycrystalline DyFeO{sub 3} (DFO) prepared through sol–gel route are reported in this paper. Phase purity and structure of the prepared sample is confirmed from x-ray diffraction and Raman spectroscopy measurements. The room temperature leakage current density (J–E) measurements indicate that Ohmic contribution and space charge limited conduction are the dominating mechanisms at low and high applied electric fields respectively. Signatures of Fe{sup 3+} spin reorientation transition (T{sub SR}) and the antiferromagnetic ordering of Dy{sup 3+} ions are observed from the temperature dependent (10–350 K) magnetization data. The M–H data measured at 2 K shows the field induced metamagnetic transition. Internal hyperfine field obtained from temperature dependent (5–300 K) {sup 57}Fe Mössbauer measurements is observed to decrease below the T{sub SR} and further found to increase till 5 K indicating the contribution of Dy{sup 3+} magnetic ordering on the hyperfine field of Fe nucleus. - Highlights: • This paper analyses structural, electrical and magnetic properties of polycrystalline multiferroic DyFeO{sub 3} sample prepared through sol–gel route. • Signatures of Fe{sup 3+} spin reorientation transition and the antiferromagnetic ordering of Dy{sup 3+} ions are observed from the temperature dependent (10-350 K) magnetization data. • From the temperature dependent {sup 57}Fe Mössbauer measurements contribution of Dy{sup 3+} magnetic ordering on the hyperfine field of Fe nucleus is observed. • Ohmic and space charge limited conduction mechanisms are found to be dominating at low and high applied electric fields respectively in DyFeO{sub 3}.

  19. Effects of magnetic annealing on structure and multiferroic properties of pure and dysprosium substituted BiFeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Shuxia [Institute of Electrical Engineering, Chinese Academy of Sciences, P.O. Box 2703, Beijing 100190 (China); Yao Yingbang [Imaging and Characterization Core Laboratory, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia); Chen Yao; Wang Dongliang; Zhang Xianping [Institute of Electrical Engineering, Chinese Academy of Sciences, P.O. Box 2703, Beijing 100190 (China); Awaji, Satoshi; Watanabe, Kazuo [High Field Laboratory for Superconducting Materials, Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Ma Yanwei, E-mail: ywma@mail.iee.ac.cn [Institute of Electrical Engineering, Chinese Academy of Sciences, P.O. Box 2703, Beijing 100190 (China)

    2012-07-15

    In this work, the effects of magnetic annealing on crystal structure and multiferroic properties of BiFeO{sub 3} and Bi{sub 0.85}Dy{sub 0.15}FeO{sub 3} have been investigated. It is found that the X-ray diffraction patterns of pure BiFeO{sub 3} samples are obviously broadened after magnetic annealing, whereas those of Bi{sub 0.85}Dy{sub 0.15}FeO{sub 3} samples are almost unchanged. Magnetic field annealing did not affect the magnetic properties of these two kinds of samples much. However, ferroelectric properties of the two materials exhibited different behaviors after magnetic field annealing. For pure BiFeO{sub 3} samples, the remnant polarizations (P{sub r}) are suppressed; in contrast, for Bi{sub 0.85}Dy{sub 0.15}FeO{sub 3} samples, P{sub r} is greatly enhanced. Possible mechanisms for the effects of magnetic field annealing have been discussed. - Highlights: Black-Right-Pointing-Pointer BiFeO{sub 3} and Bi{sub 0.85}Dy{sub 0.15}FeO{sub 3} materials were fabricated under high magnetic fields. Black-Right-Pointing-Pointer The structure of BiFeO{sub 3} material is largely affected by magnetic annealing. Black-Right-Pointing-Pointer Magnetic annealing had almost no impacts on magnetic properties of these two materials. Black-Right-Pointing-Pointer Significant changes of ferroelectric properties are observed in both materials after magnetic field annealing.

  20. Structural, magnetic and dielectric properties of Sr and V doped BiFeO{sub 3} multiferroics

    Energy Technology Data Exchange (ETDEWEB)

    Dahiya, Reetu; Agarwal, Ashish, E-mail: aagju@yahoo.com; Sanghi, Sujata; Hooda, Ashima; Godara, Priyanka

    2015-07-01

    Bi{sub 0.85}Sr{sub 0.15}FeO{sub 3} (BSFO), Bi{sub 0.85}Sr{sub 0.15}Fe{sub 0.97}V{sub 0.03}O{sub 3} (BSFVO1) and Bi{sub 0.85}Sr{sub 0.15}Fe{sub 0.95}V{sub 0.05}O{sub 3} (BSFVO2) ceramics were synthesized by solid state reaction method. X-ray diffraction studies and Rietveld refinement results indicate that all the samples crystallized in rhombohedrally distorted perovskite structure. The remnant magnetization and coercive field of BSFVO2 were greatly enhanced in comparison with BSFO. The enhancement of remnant magnetization was attributed to collapse of the spiral spin structure caused by change in bond length and bond angles of BSFO on V substitution. The enhanced value of coercive field might be attributed to decreased grain size with V substitution. BSFO sample shows dispersion in dielectric constant (έ) and dielectric loss (tan δ) values in lower frequency region. With V doping this dispersion is reduced resulting in frequency independent region. Dielectric anomaly peak due to charge defects in BSFO sample is also suppressed significantly on V substitution. BSFVO2 sample shows almost temperature stable behavior in έ and tan δ in the studied temperature range. Temperature dependence of index ‘s’ of power law suggests that overlapping large polaron tunneling model is applicable for describing the conduction mechanism in BSFO sample while small polaron tunneling model is appropriate for BSFVO1 and BSFVO2 samples in the studied temperature range. - Highlights: • Sr and V doped BiFeO{sub 3} multiferroics were synthesized by solid state reaction. • Ceramics crystallized in rhombohedrally distorted perovskite structure. • Remnant magnetization and coercive field were improved with V doping.

  1. Physical properties of the new multiferroic perovskite-like material HoMn1−xFexO3

    International Nuclear Information System (INIS)

    We report the study of the structural, magnetic and electrical properties of the multiferroic material with perovskite structure HoMn1−xFexO3 (x=0; 0.1 and 0.2) synthesized by the standard solid state reaction method. Structural analysis by X-ray diffraction (XRD) experiments shows the coexistence between two phases with the same chemical formula and with polyhedral distortions (MnO3), a phase with hexagonal symmetry (P63cm # 185) which is characteristic of the non-doped material HoMnO3 and other perovskite phase with orthorhombic symmetry (Pbnm # 62). Rietveld refinements of the experimental patterns show that the weight percentage of each phase (hexagonal or orthorhombic symmetry) depends on the degree of substitution of Fe in the Mn crystallographic sites. Measurements of polarization as a function of applied voltage at room temperature confirm a ferroelectric character for non-doped material with relative permittivity of 215.1. These measurements show that the ferroelectric behavior is deteriorated by the introduction of Fe, since in the configuration with x=0.1 (HoMn0.9Fe0.1O3) we can see ferroelectric loops with dielectric losses to small values of applied voltage and finally in the configuration with x=0.2 (HoMn0.8Fe0.2O3) the behavior is totally resistive at room temperature. Curves of magnetization as a function of temperature were carried out between 300 K and 860 K show an antiferromagnetic behavior in the three configurations of the HoMn1−xFexO3 material

  2. Anomalous coercivity enhancement with temperature and tunable exchange bias in Gd and Ti co-doped BiFeO3 multiferroics

    Science.gov (United States)

    Ahmmad, Bashir; Islam, M. Z.; Billah, Areef; Basith, M. A.

    2016-03-01

    We have investigated the effects of temperature on the magnetic properties of the Bi0.9Gd0.1Fe1-x Ti x O3 (x  =  0.00-0.20) multiferroic system. Unexpectedly, the coercive fields (H c ) of this multiferroic system increased with increasing temperature. The coercive fields and remanent magnetization were higher over a wide range of temperatures in sample x  =  0.10, i.e. in a sample with a composition Bi0.9Gd0.1Fe0.9Ti0.1O3 than those of x  =  0.00 and 0.20 compositions. Therefore, we carried out temperature-dependent magnetization experiments extensively for sample x  =  0.10. The magnetic hysteresis loops at different temperatures exhibit an asymmetric shift towards the magnetic field axes, which indicates the presence of an exchange bias effect in this material system. The hysteresis loops were also carried out at temperatures of 150 K and 250 K by cooling down the sample from 300 K in various cooling magnetic fields ({{H}\\text{cool}} ). The exchange bias field ({{H}\\text{EB}} ) values increased with {{H}\\text{cool}} and decreased with temperature. The {{H}\\text{EB}} values were tunable by field cooling at temperatures of up to 250 K.

  3. Optical diode effect at THz frequencies of spin-wave excitations in the room-temperature multiferroic BiFeO3

    Science.gov (United States)

    Rõõm, Toomas; Nagel, U.; Bordács, S.; Kézsmárki, I.; Yi, H. T.; Cheong, S.-W.; Lee, J. H.; Fishman, R. S.

    We studied the unidirectional transmission of THz radiation in BiFeO3 crystals, the unique multiferroic compound offering a real potential for room-temperature applications. We found that the optical magnetoelectric effect generated by spin waves in BiFeO3 is robust enough to cause considerable nonreciprocal directional dichroism in the GHz-THz range even at room temperature. The optical magnetoelectric effect in BiFeO3 is dominated by two types of spin-current induced polarizations, while the exchange-striction and single-ion polarization terms do not significantly contribute to it. Our work demonstrates that the nonreciprocal directional dichroism spectra and their theoretical analysis provide microscopic model of the magnetoelectric couplings in multiferroic materials. We acknowledge the Estonian Grant IUT23-3; the Hungarian OTKA K 108918, OTKA PD 111756, Bolyai 00565/14/11; the DOE, Office of Sciences, Basic Energy Sciences, Mat. Sciences and Eng. Div., and the DOE Grant DE-FG02-07ER46382.

  4. Neutron diffraction studies on chemical and magnetic structure of multiferroic PbFe0.67W0.33O3

    International Nuclear Information System (INIS)

    We report on the single phase synthesis and room temperature structural characterization of PbFe0.67W0.33O3 (PFW) multiferroic. The PFW was synthesized by low temperature sintering, Columbite method. Analysis of powder XRD pattern exhibits single phase formation of PFW with no traces of pyrochlore phase. Detailed analysis of room temperature neutron diffraction (ND) reveals cubic phase at room temperature, space group Pm-3m. The ND pattern clearly reveals magnetic Bragg peak at 2θ = 18.51° (Q = 1.36Å−1). The refinement of magnetic structure reveals G-type antiferromagnetic structure in PFW at room temperature. The dielectric constant and loss tangent decreases with increasing frequency. The room temperature P-E measurements shows a non-linear slim hysteresis, typical nature of relaxor multiferroics, with saturation and remnant polarizations of Ps = 1.50 μC/cm2 and Pr = 0.40 μC/cm2, respectively

  5. Crystalline and spin chiralities in multiferroics with langasite-type structure and Fe{sub 1–x}Co{sub x}Si crystals

    Energy Technology Data Exchange (ETDEWEB)

    Pikin, S. A., E-mail: pikin@ns.crys.ras.ru; Lyubutin, I. S.; Dudka, A. P. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2015-09-15

    It is shown that, when magnetic ordering occurs in layered iron-containing langasites (sp. gr. P321), one of the reasons for spin chiralities of different signs is the presence of structural chirality (the existence of inversion twins), which, in turn, is due to the nonsymmetricity of these crystals. Spin helicoids arise in these multiferroics at split sites of Fe{sup 3+} ions below the Néel point. The direction of electric polarization vectors coincides with the direction of the magnetic helicoid axes because of the piezoelectric properties of these materials. Due to the magnetostriction effects, structural chirality wave vector k{sub z} exceeds the magnetic helicoid wave vector by a factor of 2: k{sub z} = 2q{sub z}. The temperatures of transitions to the chiral structural and chiral magnetic states may differ. In particular, if the structural transition initial temperature exceeds the magnetic transition temperature (Τ{sub U}> Τ{sub M}), structural displacements may arise in the absence of magnetism at Τ{sub M} < Τ < Τ{sub U}. In noncentrosymmetric Fe{sub 1–x}Co{sub x}Si crystals (sp. gr. P2{sub 1}3), which are not multiferroics, magnetic chirality is due to the Dzyaloshinski–Moriya interaction. The dependence of the moduli of incommensurate wave number of the corresponding helicoid on the atomic composition of the crystals under consideration is nonmonotonic.

  6. Magnetic and electrical properties on possible room temperature hybrid multiferroic BaTiO3/La2/3Sr1/3MnO3

    Science.gov (United States)

    Ordoñez, John Edward; Gómez, María Elena; Lopera Muñoz, Wilson; Prieto, Pedro Antonio; Thin Film Group Team; Center of Excellence on Novel Materials-CENM, Cali, Colombia Team

    2015-03-01

    We addressed to deposit the ferromagnetic phase of the La1-xSrxMnO3 and the ferroelectric BaTiO3 for possible hybrid multiferroic heterostructure. We have optimized the growth parameters for depositing BaTiO3(BTO) / La2/3Ca1/3MnO3(LCMO) / (001) SrTiO3 by sputtering RF and DC, respectively, in pure oxygen atmosphere and a substrate temperature of 830°C. Keeping fixed the magnetic layer thickness (tLSMO = 40 nm) and varying the thickness of the ferroelectric layer (tBTO = 20, 40, 80, 100 nm). We want to point out the influence of the thicknesses ratio (tBTO/tLSMO) on electrical and magnetic properties. From x-ray diffraction (XRD) analysis, we found the bragg peaks for LSMO maintain its position but BTO peak shift to lower Bragg angle indicating a strained BTO film. Magnetization and polarization measurements indicate a possible multiferroic behavior in the bilayers. Hysteresis loop measurements of bilayers show ferromagnetic behavior. Authors thank Instituto de Nanociencia de Aragón, Zaragoza, Spain. Work partially supported by COLCIENCIAS-UNIVALLE Project 110656933104 Contract No. 2013-0002, CI 7917 and CI 7978.

  7. Magnetodielectric properties of Bi4NdTi3Fe0.7Co0.3O15 multiferroic system

    International Nuclear Information System (INIS)

    Highlights: • The BNTFC multiferroic ceramic exhibits strong ferromagnetism at room temperature. • Obvious magnetodielectric effect was investigated in detail at room temperature. • The MD (=(ε(H)-ε(0))/(ε(0)) ×100) exhibits a linear relation with M4 rather than M2. - Abstract: Bi4NdTi3Fe0.7Co0.3O15 polycrystalline samples were synthesized following a multicalcination procedure. X-ray analysis indicated a four-layer Aurivillius phase with an orthorhombic symmetry was obtained. The multiferroic properties of the sample at room temperature were demonstrated by the ferroelectric (2Pr = 7.23 μC/cm2, 2Ec = 35.72 kV/cm at applied electric field 70 kV/cm) and magnetic (2Mr = 232 m emu/g, 2Hc = 769 Oe at applied magnetic field 1.07 T) hysteresis loops. Obvious magnetodielectric effect which is dependent on frequency was observed at room temperature. It is found that the magnetodielectric effect exhibits a linear relation with M4 rather than M2 which may be due to the complicated spin-pair correlation interactions among next nearest neighbors. The present study suggests the possibility of magnetic ions doped Bi4NdTi3FeO15 as a potential candidate for novel multifunctional device application

  8. Coexisting ferroelectric and magnetic morphotropic phase boundaries in Dy-modified BiFeO3-PbTiO3 multiferroics

    Science.gov (United States)

    Zhuang, Jian; Su, Lun-Wei; Wu, Hua; Bokov, Alexei A.; Liu, Ming; Ren, Wei; Ye, Zuo-Guang

    2015-11-01

    Morphotropic phase boundary (MPB) in ferroelectric solid solutions can significantly enhance the dielectric and piezoelectric performances of the materials. Similarly, magnetic MPB has been found to exist in a few ferromagnets and is proved to be greatly beneficial to the magnetostrictive response. In this letter, we report the finding of a magnetic MPB in the multiferroic 0.66Bi1-xDyxFeO3-0.34PbTiO3 system, which overlaps the structural MPB of ferroelectric phases. A (weak) ferromagnetic state is induced at room temperature by Dy for the rhombohedral compositions with x ≥ 0.10. Upon cooling down from room temperature, the tetragonal compositions (x ≤ 0.05) show only one magnetic phase transition from the paramagnetic to antiferromagnetic phase, while the rhombohedral compositions exhibit a series of magnetic phase transitions from the (weak) ferromagnetic state to an antiferromagnetic order then to another weak ferromagnetic phase. A magneto-structural phase diagram has been established that reveals the presence of a magnetic MPB and a ferroelectric MPB. More significantly, the ferroelectric and magnetic MPB regions are found to overlap with each other, pointing to interesting kinds of multiferroic couplings.

  9. Biomimetic thin film synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Graff, G.L.; Campbell, A.A.; Gordon, N.R.

    1995-05-01

    The purpose of this program is to develop a new process for forming thin film coatings and to demonstrate that the biomimetic thin film technology developed at PNL is useful for industrial applications. In the biomimetic process, mineral deposition from aqueous solution is controlled by organic functional groups attached to the underlying substrate surface. The coatings process is simple, benign, inexpensive, energy efficient, and particularly suited for temperature sensitive substrate materials (such as polymers). In addition, biomimetic thin films can be deposited uniformly on complex shaped and porous substrates providing a unique capability over more traditional line-of-sight methods.

  10. Thinning Invariant Partition Structures

    CERN Document Server

    Starr, Shannon

    2011-01-01

    A partition structure is a random point process on $[0,1]$ whose points sum to 1, almost surely. In the case that there are infinitely many points to begin with, we consider a thinning action by: first, removing points independently, such that each point survives with probability $p>0$; and, secondly, rescaling the remaining points by an overall factor to normalize the sum again to 1. We prove that the partition structures which are "thinning divisible" for a sequence of $p$'s converging to 0 are mixtures of the Poisson-Kingman partition structures. We also consider the property of being "thinning invariant" for all $p \\in (0,1)$.

  11. Ceramic Composite Thin Films

    Science.gov (United States)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  12. Thin Solid Oxide Cell

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material, at least one metal and a catalyst...... material, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same. The present invention also relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous...... cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material and a catalyst material, wherein the electrolyte material is doper zirconia, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same. The...

  13. Thin film device applications

    CERN Document Server

    Kaur, Inderjeet

    1983-01-01

    Two-dimensional materials created ab initio by the process of condensation of atoms, molecules, or ions, called thin films, have unique properties significantly different from the corresponding bulk materials as a result of their physical dimensions, geometry, nonequilibrium microstructure, and metallurgy. Further, these characteristic features of thin films can be drasti­ cally modified and tailored to obtain the desired and required physical characteristics. These features form the basis of development of a host of extraordinary active and passive thin film device applications in the last two decades. On the one extreme, these applications are in the submicron dimensions in such areas as very large scale integration (VLSI), Josephson junction quantum interference devices, magnetic bubbles, and integrated optics. On the other extreme, large-area thin films are being used as selective coatings for solar thermal conversion, solar cells for photovoltaic conver­ sion, and protection and passivating layers. Ind...

  14. Thin silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hall, R.B.; Bacon, C.; DiReda, V.; Ford, D.H.; Ingram, A.E.; Cotter, J.; Hughes-Lampros, T.; Rand, J.A.; Ruffins, T.R.; Barnett, A.M. [Astro Power Inc., Solar Park, Newark, DE (United States)

    1992-12-01

    The silicon-film design achieves high performance by using a dun silicon layer and incorporating light trapping. Optimally designed thin crystalline solar cells (<50 microns thick) have performance advantages over conventional thick devices. The high-performance silicon-film design employs a metallurgical barrier between the low-cost substrate and the thin silicon layer. Light trapping properties of silicon-film on ceramic solar cells are presented and analyzed. Recent advances in process development are described here.

  15. Ferroelectric thin films

    International Nuclear Information System (INIS)

    The area of ferroelectric thin films has expanded rapidly recently with the advent of high quality multi-oxide deposition technology. Advances in thin film quality has resulted in the realization of new technologies not achievable through classical bulk ceramic processing techniques. An example of this progress is the co-processing of ferroelectric thin films with standard semiconductor silicon and GaAs integrated circuits for radiation hard, non-volatile memory products. While the development of this class of products is still embryonic, the forecasted market potential is rapidly out distancing the combined developmental effort. Historically the greatest use of bulk ferroelectric material has been in sensor technology, utilizing the pyroelectric and piezoelectric properties of the material. By comparison, a relatively small development effort has been reported for ferroelectric thin film senor technology, a field sure to provide exciting advances in the future. The papers in this proceedings volume were presented at the first symposium dedicated to the field of ferroelectric thin films held by the Materials Research Society at the Spring 1990 Meeting in San Francisco, CA, April 16-20, 1990. The symposium was designed to provide a comprehensive tutorial covering the newest advances of ferroelectric thin films, including material systems, new deposition techniques and physical, electrical and electro-optic characterization

  16. Multiferroic properties in Zn and Ni co-doped BiFeO{sub 3} ceramics by solution combustion method (SCM)

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhari, Y.A., E-mail: yogeshchaudhari2007@yahoo.com [Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon 425 001, Maharashtra (India); Department of Engineering Sciences and Humanities (DESH), SRTTC - FOE, Pune 410 405, Maharashtra (India); Singh, A. [Magnetics and Advanced Ceramics Laboratory, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110 016 (India); Mahajan, C.M. [Department of Engineering Sciences and Humanities (DESH), Vishwakarma Institute of Technology, Pune 411 037, Maharashtra (India); Jagtap, P.P.; Abuassaj, E.M. [Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon 425 001, Maharashtra (India); Chatterjee, R. [Magnetics and Advanced Ceramics Laboratory, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110 016 (India); Bendre, S.T., E-mail: bendrest@gmail.com [Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon 425 001, Maharashtra (India)

    2013-12-15

    In present paper, we synthesize the multiferroic Bi{sub 1−x}Zn{sub x}Fe{sub 1−y}Ni{sub y}O{sub 3} (x=y=0.025, 0.05, 0.075 and 0.1) ceramics by using solution combustion method (SCM). The room temperature ferroelectric and magnetic hysteresis loops present the co-existence of magnetism and ferroelectricity in a single phase. This ferroelectric hysteresis loops exhibit an unsaturated behavior and represents a partial reversal of polarization at room temperature. Beside, this it was found that the room temperature magnetization measurement is giving rise to the appearance of weak ferromagnetism. The Bi{sub 0.975}Zn{sub 0.025}Fe{sub 0.975}Ni{sub 0.025}O{sub 3} and Bi{sub 0.9}Zn{sub 0.1}Fe{sub 0.9}Ni{sub 0.1}O{sub 3} ceramics display the clear evidence of dielectric anomaly around 300 and 325 °C which corresponds to antiferromagnetic to paramagnetic phase transition of BiFeO{sub 3} ceramics. The structural study shows the Bi{sub 1−x}Zn{sub x}Fe{sub 1−y}Ni{sub y}O{sub 3} (x=y=0.025, 0.05, 0.075 and 0.1) ceramics have rhombhohedral perovskite structure. The surface morphology of the samples was examined by SEM. - Highlights: • Bi{sub 1−x}Zn{sub x}Fe{sub 1−y}Ni{sub y}O{sub 3} multiferroic ceramics. • Solution Combustion Method (SCM). • Ferroelectric, dielectric and magnetic properties. • To make high temperature synthesized Bi{sub 1−x}Zn{sub x}Fe{sub 1−y}Ni{sub y}O{sub 3} multiferroic ceramics. • First time we have synthesized the Bi{sub 1−x}Zn{sub x}Fe{sub 1−y}Ni{sub y}O{sub 3} ceramics by solution combustion method.

  17. Effect of rare earth substitution on properties of barium strontium titanate ceramic and its multiferroic composite with nickel cobalt ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Pahuja, Poonam [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Kotnala, R.K. [National Physical Laboratory, Delhi 110012 (India); Tandon, R.P., E-mail: rt241150@gmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

    2014-12-25

    Highlights: • Rare earth ions Dy{sup 3+}, Gd{sup 3+} and Sm{sup 3+} have been substituted in Ba{sub 0.95}Sr{sub 0.05}TiO{sub 3} (BST). • Ni{sub 0.8}Co{sub 0.2}Fe{sub 2}O{sub 4} has been used as ferrimagnetic phase to obtain composites. • Substitution of these ions increases dielectric constant of BST and composites. • Magnetoelectric coefficient of composites increases on substitution of these ions. - Abstract: Effect of substitution of rare earth ions (Dy{sup 3+}, Gd{sup 3+} and Sm{sup 3+}) on various properties of Ba{sub 0.95}Sr{sub 0.05}TiO{sub 3} (BST) i.e. the composition Ba{sub 0.95−1.5x}Sr{sub 0.05}R{sub x}TiO{sub 3} (where x = 0.00, 0.01, 0.02, 0.03 and R are rare earths Dy, Gd, Sm) and that of their multiferroic composite with Ni{sub 0.8}Co{sub 0.2}Fe{sub 2}O{sub 4} (NCF) has been studied. Shifting of peaks corresponding to different compositions in the X-ray diffraction pattern confirmed the substitution of rare earth ions at both Ba{sup 2+} and Ti{sup 4+} sites in BST. It is clear from scanning electron microscopy (SEM) images that rare earth substitution in BST increases its grain size in both pure and composite samples. Substitution of rare earth ions results in increase in value of dielectric constant of pure and composite samples. Sm substitution in BST significantly decreases its Curie temperature. Dy substituted pure and composite samples possess superior ferroelectric properties as confirmed by polarization vs electric field (P–E) loops. Composite samples containing Dy, Gd and Sm substituted BST as ferroelectric phase possess lower values of remanent and saturation magnetizations in comparison to composite sample containing pure BST as ferroelectric phase (BSTC). Rare earth substituted composite samples possess higher value of magnetoelectric coefficient as compared to that for BSTC.

  18. Structural, Raman, and dielectric studies on multiferroic Mn-doped Bi 1-xLax FeO 3 ceramics

    KAUST Repository

    Xing, Zhibiao

    2014-04-03

    Multiferroic Bi1-xLaxFeO3 [BLFO (x)] ceramics with x = 0.10-0.50 and Mn-doped BLFO (x = 0.30) ceramics with different doping contents (0.1-1.0 mol%) were prepared by solid-state reaction method. They were crystallized in a perovskite phase with rhombohedral symmetry. In the BLFO (x) system, a composition (x)-driven structural transformation (R3c→C222) was observed at x = 0.30. The formation of Bi2Fe 4O9 impure phase was effectively suppressed with increasing the x value, and the rhombohedral distortion in the BLFO ceramics was decreased, leading to some Raman active modes disappeared. A significant red frequency shift (~13 cm-1) of the Raman mode of 232 cm-1 in the BLFO ceramics was observed, which strongly perceived a significant destabilization in the octahedral oxygen chains, and in turn affected the local FeO6 octahedral environment. In the Mn-doped BLFO (x = 0.30) ceramics, the intensity of the Raman mode near 628 cm-1 was increased with increasing the Mn-doping content, which was resulted from an enhanced local Jahn-Teller distortions of the (Mn,Fe)O6 octahedra. Electron microscopy images revealed some changes in the ceramic grain sizes and their morphologies in the Mn-doped samples at different contents. Wedge-shaped 71° ferroelectric domains with domain walls lying on the {110} planes were observed in the BLFO (x = 0.30) ceramics, whereas in the 1.0 mol% Mn-doped BLFO (x = 0.30) samples, 71° ferroelectric domains exhibited a parallel band-shaped morphology with average domain width of 95 nm. Dielectric studies revealed that high dielectric loss of the BLFO (x = 0.30) ceramics was drastically reduced from 0.8 to 0.01 (measured @ 104 Hz) via 1.0 mol% Mn-doping. The underlying mechanisms can be understood by a charge disproportion between the Mn4+ and Fe2+ in the Mn-doped samples, where a reaction of Mn4+ + Fe2+→Mn3+ + Fe3+ is taken place, resulting in the reduction in the oxygen vacancies and a suppression of the electron hopping from Fe3+ to Fe2+ ions

  19. Giant magnetoelectric effect in thin magnetic films utilizing inter-ferroelectric transitions

    Science.gov (United States)

    Finkel, Peter; Staruch, Margo

    There has recently been much interest to multiferroic magnetoelectric composites based on relaxor ferroelectric single crystals as potential candidates for devices such as magnetic field sensors, energy harvesters, or transducers. Large magnetoelectric coupling coefficient is prerequisite for superior device performance in a broad range of frequencies and functioning conditions. In magnetoelectric heterostructures based on ternary relaxors Pb(In1/2Nb1/2) O3-Pb(Mg1/3Nb2/3) O3-PbTiO3 (PIN-PMN-PT) crystal better operational range and temperature stability as compared to binary relaxors can be achieved. Giant linear converse magnetoelectric coupling up to 2 x 10-6 s m-1 were observed in heterostructural composites with multilayered FeCo/Ag deposited on (011) PIN-PMN-PT crystals. Further enhancement of magnetoelectric coupling is demonstrated by utilizing inter-ferroelctric rhombohedral - orthorhombic phase transitions in PIN-PMN-PT Mechanical clamping was a precondition to utilize this inter-ferroelectric transition mode to bring the crystal to a point just below its transformation threshold when very small perturbations at the input will cause large swings at the output generating a sharp uniaxial increase in strain (~0.5 %) and polarization change, giving rise to nonlinear effects. Details of these results and their implications will be presented. Giant magnetoelectric effect in thin magnetic fillms utilizing inter-ferroelectric transitions.

  20. Thin film photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Zweibel, K; Ullal, H S

    1989-05-01

    Thin films are considered a potentially attractive technological approach to making cost-effective electricity by photovoltaics. Over the last twenty years, many have been investigated and some (cadmium telluride, copper indium diselenide, amorphous silicon) have become leading candidates for future large-scale commercialization. This paper surveys the past development of these key thin films and gives their status and future prospects. In all cases, significant progress toward cost-effective PV electricity has been made. If this progress continues, it appears that thin film PV could provide electricity that is competitive for summer daytime peaking power requirements by the middle of the 1990s; and electricity in a range that is competitive with fossil fuel costs (i.e., 6 cents/kilowatt-hour) should be available from PV around the turn of the century. 22 refs., 9 figs.

  1. Thin film temperature sensor

    Science.gov (United States)

    Grant, H. P.; Przybyszewski, J. S.

    1980-01-01

    Thin film surface temperature sensors were developed. The sensors were made of platinum-platinum/10 percent rhodium thermocouples with associated thin film-to-lead wire connections and sputtered on aluminum oxide coated simulated turbine blades for testing. Tests included exposure to vibration, low velocity hydrocarbon hot gas flow to 1250 K, and furnace calibrations. Thermal electromotive force was typically two percent below standard type S thermocouples. Mean time to failure was 42 hours at a hot gas flow temperature of 1250 K and an average of 15 cycles to room temperature. Failures were mainly due to separation of the platinum thin film from the aluminum oxide surface. Several techniques to improve the adhesion of the platinum are discussed.

  2. Charge, spin and orbital order in the candidate multiferroic material LuFe{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Groot, Joost de

    2012-06-28

    This thesis is a detailed study of the magnetic, structural and orbital order parameters of the candidate multiferroic material LuFe{sub 2}O{sub 4}. Multiferroic oxides with a strong magnetoelectric coupling are of high interest for potential information technology applications, but they are rare because the traditional mechanism of ferroelectricity is incompatible with magnetism. Consequently, much attention is focused on various unconventional mechanisms of ferroelectricity. Of these, ferroelectricity originating from charge ordering (CO) is particularly intriguing because it potentially combines large electric polarizations with strong magneto-electric coupling. However, examples of oxides where this mechanism occurs are exceedingly rare and none is really well understood. LuFe{sub 2}O{sub 4} is often cited as the prototypical example of CO-based ferroelectricity. In this material, the order of Fe valences has been proposed to render the triangular Fe/O bilayers polar by making one of the two layers rich in Fe{sup 2+} and the other rich in Fe{sup 3+}, allowing for a possible ferroelectric stacking of the individual bilayers. Because of this new mechanism for ferroelectricity, and also because of the high transition temperatures of charge order (T{sub CO} {proportional_to}320K) and ferro magnetism (T{sub N}{proportional_to}240 K) LuFe{sub 2}O{sub 4} has recently attracted increasing attention. Although these polar bilayers are generally accepted in the literature for LuFe{sub 2}O{sub 4}, direct proof is lacking. An assumption-free experimental determination of whether or not the CO in the Fe/O bilayers is polar would be crucial, given the dependence of the proposed mechanism of ferroelectricity from CO in LuFe{sub 2}O{sub 4} on polar bilayers. This thesis starts with a detailed characterization of the macroscopic magnetic properties, where growing ferrimagnetic contributions observed in magnetization could be ascribed to increasing oxygen off-stoichiometry. The

  3. Thin sums matroids and duality

    CERN Document Server

    Afzali, Hadi

    2012-01-01

    Thin sums matroids were introduced to extend the notion of representability to non-finitary matroids. We give a new criterion for testing when the thin sums construction gives a matroid. We show that thin sums matroids over thin families are precisely the duals of representable matroids (those arising from vector spaces). We also show that the class of tame thin sums matroids is closed under duality and under taking minors, by giving a new characterisation of the matroids in this class. Finally, we show that all the matroids naturally associated to an infinite graph are tame thin sums matroids.

  4. Thin film ceramic thermocouples

    Science.gov (United States)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  5. Thin films and nanomaterials

    International Nuclear Information System (INIS)

    The objective of this book is to disseminate the most recent research in Thin Films, Nanomaterials, Corrosion and Metallurgy presented at the International Conference on Advanced Materials (ICAM 2011) held in PSG College of Technology, Coimbatore, India during 12-16 December 2011. The book is a compilation of 113 chapters written by active researchers providing information and critical insights into the recent advancements that have taken place. Important new applications are possible today in the fields of microelectronics, opto-electronics, metallurgy and energy by the application of thin films on solid surfaces. Recent progress in high vacuum technology and new materials has a remarkable effect in thin film quality and cost. This has led to the development of new single or multi-layered thin film devices with diverse applications in a multitude of production areas, such as optics, thermal barrier coatings and wear protections, enhancing service life of tools and to protect materials against thermal and atmospheric influence. On the other hand, thin film process techniques and research are strongly related to the basic research activities in nano technology, an increasingly important field with countless opportunities for applications due to the emergence of new properties at the nanoscale level. Materials and structures that are designed and fabricated at the nano scale level, offer the potential to produce new devices and processes that may enhance efficiencies and reduce costs in many areas, as photovoltaic systems, hydrogen storage, fuel cells and solar thermal systems. In the book, the contributed papers are classified under two sections i) thin films and ii) nanomaterials. The thin film section includes single or multi layer conducting, insulating or semiconducting films synthesized by a wide variety of physical or chemical techniques and characterized or analyzed for different applications. The nanomaterials section deals with novel or exciting materials

  6. First principles prediction of interfacial magnetoelectric coupling in tetragonal La2/3Sr1/3MnO3/BiFeO3 multiferroic superlattices.

    Science.gov (United States)

    Feng, Nan; Mi, Wenbo; Wang, Xiaocha

    2015-05-28

    The electronic structure and magnetic properties of the tetragonal La2/3Sr1/3MnO3/BiFeO3 multiferroic superlattices with different interfacial terminations have been studied by first-principles calculations. Our results for all the models of the tetragonal La2/3Sr1/3MnO3/BiFeO3 superlattices exhibit a metallic electronic structure. More importantly, we find that the magnetoelectric coupling can be realized in the tetragonal La2/3Sr1/3MnO3/BiFeO3 heterostructures by means of exchange bias, which can be attributed to the interfacial exchange coupling. These findings are useful for magnetoelectrically controlled spintronic devices. PMID:25940540

  7. Temperature-dependent interplay of Dzyaloshinskii-Moriya interaction and single-ion anisotropy in multiferroic BiFeO3.

    Science.gov (United States)

    Jeong, Jaehong; Le, Manh Duc; Bourges, P; Petit, S; Furukawa, S; Kim, Shin-Ae; Lee, Seongsu; Cheong, S-W; Park, Je-Geun

    2014-09-01

    Low-energy magnon excitations in multiferroic BiFeO3 were measured in detail as a function of temperature around several Brillouin zone centers by inelastic neutron scattering experiments on single crystals. Unique features around 1 meV are directly associated with the interplay of the Dzyaloshinskii-Moriya interaction and a small single-ion anisotropy. The temperature dependence of these and the exchange interactions were determined by fitting the measured magnon dispersion with spin-wave calculations. The spectra best fit an easy-axis type magnetic anisotropy and the deduced exchange and anisotropy parameters enable us to determine the anharmonicity of the magnetic cycloid. We then draw a direct connection between the changes in the parameters of spin Hamiltonian with temperature and the physical properties and structural deformations of BiFeO3. PMID:25238381

  8. Structural transitions under high-pressure in a langasite-type multiferroic Ba3TaFe3Si2O14

    Science.gov (United States)

    Naumov, P. G.; Ksenofontov, V.; Lyubutin, I. S.; Medvedev, S. A.; Barkalov, O. I.; Palasyuk, T.; Magos-Palasyuk, E.; Felser, C.

    2015-11-01

    The iron containing langasite family compound Ba3Ta57Fe3Si2O14 was studied at high pressure up to 30 GPa at room temperature by means of in situ X-ray diffraction, Raman and Mössbauer spectroscopies in diamond anvil cell. Two structural transitions at pressures ˜5 and ˜20 GPa are observed. At ˜5 GPa, the low-pressure trigonal P321 phase undergoes phase transition to the most likely P3 structure as manifested by slight increase in the c/a ratio and by anomalies of the Mössbauer and Raman spectra parameters. At ˜20 GPa, the first order phase transition to monoclinic structure occurred with a drop of unit cell volume by 9%. The appearance of the ferroelectric state at such transitions is discussed in connection with the multiferroic properties.

  9. Structure and magnetic properties of perovskite-like multiferroic PbFe0.5Nb0.5O3

    International Nuclear Information System (INIS)

    PbFe0.5Nb0.5O3 compound (PFN) is a well-known multiferroic material undergoing a paraelectric(PE)-to-ferroelectric(FE) phase transition at ∼ 380 K. The cubic structure in the PE state is distorted in the FE state to the tetragonal (below 376 K), and subsequently to the monoclinic structure. Inspecting magnetism, two diffuse magnetic phase transitions were reported at TN = 150 K and Tm = 10 K. In our work, we have investigated samples derived from the PFN, prepared by different methods. The crystal structure, grain size and phase composition of the materials was determined by powder XRD and SEM analysis. Study of magnetization and a.c. susceptibility confirmed presence of the two anomalies of magnetic origin at 150 K and 10 K, respectively, in most of the samples.

  10. FAST TRACK COMMUNICATION: Ferroelectric properties and dielectric responses of multiferroic BiFeO3 films grown by RF magnetron sputtering

    Science.gov (United States)

    Qi, Xiaoding; Tsai, Po-Chou; Chen, Yi-Chun; Ko, Cheng-Hung; Huang, Jung-Chun-Andrew; Chen, In-Gann

    2008-12-01

    Multiferroic BiFeO3 films have been grown on LaNiO3-x/SrTiO3 and Pt/Si substrates by RF magnetron sputtering. The films showed fully saturated ferroelectric hysteresis loops with large remanent polarization of 64 µC cm-2, suitable for most device applications. Piezoresponse force microscopy confirmed that the films were electrically writable. In addition to the high-frequency intrinsic dielectric loss of epitaxial films, the Argand diagram also revealed low-frequency contributions from both dc conductivity and interfacial polarization at electrodes. For polycrystalline films on Pt/Si, the dominant contribution to dielectric loss was space charge polarization at grain boundaries.

  11. Structural study in ceramic multiferroic Co{sub 3}TeO{sub 6} and analysis of possible Co-Co networks

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Harishchandra; Sinha, A. K., E-mail: anil@rrcat.gov.in; Ghosh, Haranath; Singh, M. N.; Upadhyay, Anuj [Indus Synchrotron utilization Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 India (India)

    2015-06-24

    We show that there exist four networks (Co1-Co4, Co2-Co3-Co5, Co1-Co5 and Co2-Co3-Co4) in contrast to earlier observations of two networks (Co1-Co4 and Co2-Co3-Co5) in Co{sub 3}TeO{sub 6} (CTO) multiferroic [Phys. Rev. B 88, 184427 (2013)]. Due to five crystallographically different sites of Co ions coordinated by [IV], [V] and [VI] oxygen atoms, the coordination polyhedra exhibit strong distortions from their respective ideal polyhedra, and thus potentially allow to resolve low-symmetry crystal field splittings of d-d electronic transitions. Our structural analysis using Rietveld refinements on the room temperature Synchrotron X-ray Diffraction data indicates possible magnetic order, and may provide a basis for the complex and multiple magnetic transitions of CTO at low temperature.

  12. X-ray diffraction study of Ba3TaFe3Si2O14 single crystal—a promising langasite-type multiferroic

    International Nuclear Information System (INIS)

    Ba3TaFe3Si2O14 single crystals (sp. gr. P321, Z = 1), promising langasite-type multiferroics, have been grown by floating zone melting. An accurate X-ray diffraction study of Ba3TaFe3Si2O14 single crystal has been performed using two datasets, obtained independently for two different orientations of the same sample on a diffractometer equipped with a CCD area detector at 295 K. Structure refinement is performed based on an averaged dataset: a = 8.5355(1) Å, c = 5.2332(1) Å, sp. gr. P321, Z = 1; the R factors of model structure refinement were found to be R/wR = 1.02/1.23% for 4552 independent reflections. Disordering asymmetry is revealed for the magnetic Fe ion in the 3f site and the Ba cation in the 3e site

  13. Correlation of magnetoelectric coupling in multiferroic BaTiO3-BiFeO3 superlattices with oxygen vacancies and antiphase octahedral rotations

    International Nuclear Information System (INIS)

    Multiferroic (BaTiO3-BiFeO3) × 15 multilayer heterostructures show high magnetoelectric (ME) coefficients αME up to 24 V/cm·Oe at 300 K. This value is much higher than that of a single-phase BiFeO3 reference film (αME = 4.2 V/cm·Oe). We found clear correlation of ME coefficients with increasing oxygen partial pressure during growth. ME coupling is highest for lower density of oxygen vacancy-related defects. Detailed scanning transmission electron microscopy and selected area electron diffraction microstructural investigations at 300 K revealed antiphase rotations of the oxygen octahedra in the BaTiO3 single layers, which are an additional correlated defect structure of the multilayers

  14. Antiferromagnetic ordering in spin-chain multiferroic Gd{sub 2}BaNiO{sub 5} studied by electronic spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y. M.; Ruan, M. Y.; Cheng, J. J.; Sun, Y. C. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Ouyang, Z. W., E-mail: zwouyang@mail.hust.edu.cn; Xia, Z. C. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074 (China); Rao, G. H. [School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China)

    2015-06-14

    High-field electron spin resonance (ESR) has been employed to study the antiferromagnetic (AFM) ordering state (T < T{sub N} = 55 K) of spin-chain multiferroic Gd{sub 2}BaNiO{sub 5}. The spin reorientation at T{sub SR} = 24 K is well characterized by the temperature-dependent ESR spectra. The magnetization data evidence a field-induced spin-flop transition at 2 K. The frequency-field relationship of the ESR data can be explained by conventional AFM resonance theory with uniaxial anisotropy, in good agreement with magnetization data. Related discussion on zero-field spin gap is presented.

  15. Sintering time effect on crystal structure and magnetic properties of Bi0.8La0.2FeO3 multiferroics

    Science.gov (United States)

    Singh, Ompal; Agarwal, Ashish; Sanghi, Sujata; Singh, Jogender

    2016-05-01

    Effect of sintering time over the structure and magnetic properties has been studid in Bi0.8La0.2FeO3 multiferroic ceramics prepared by solid state reaction technique. The structure changes with the advent mixed phase rhombohedral and orthorhombic symmetry to immaculate orthorhombic structure with sintering time from 2 to 3 hour, as revealed by means of the simulation of XRD patterns via Rietveld analysis through FullProf software. The M - H plots depict decent enhancement in magnetization with values of remnant magnetization (Mr) from 0.01868emu/g to 0.09357emu/g while the sintering time is varied from 2 to 3 hour. The metamagnetic transition may be attributed to the crumpling of the modulated spin cycloid existing inherently in the pristine compound. The presented study may have considerable impact in commercial as well as advanced electronic applications.

  16. Improved multiferroic properties and a novel magnetic behavior of Bi0.8La0.2Fe1-xCoxO3 nanoparticles

    International Nuclear Information System (INIS)

    Bi0.8La0.2Fe1-xCoxO3 nanoparticles of single phase (BLFCOx, x=0, 0.005, 0.01, 0.02) were prepared by a sol-gel method using polyvinyl alcohol as a surfactant. Co substitution at Fe site improved further dielectric properties of Bi0.8La0.2FeO3 nanoparticles in the frequency range below 25 MHz at room temperature. Magnetization at 10 kOe, coercivities, and remanence of BLFCOx nanoparticles increased with increasing Co content. It is interesting that the hysteresis loop of all the BLFCOx nanoparticles presented a wasp-waisted shape. The property can open an important way to design new multiferroic applications of low hysteresis loss in low magnetic fields.

  17. Magnetocaloric effect in multiferroic Y-type hexaferrite Ba0.5Sr1.5Zn2(Fe0.92Al0.0812O22

    Directory of Open Access Journals (Sweden)

    Wenfei Xu

    2014-06-01

    Full Text Available Magnetocaloric effect is investigated in multiferroic Ba0.5Sr1.5Zn2(Fe0.92Al0.0812O22 ceramic with Y-type hexagonal system. Three magnetic transitions, from alternating longitudinal conical to mixed conical at ∼240 K, to ferrimagnetic at ∼297 K, further to paramagnetic at ∼702 K, are unambiguously determined. Furthermore, obvious MCE is shown, and the maximum values of the magnetic entropy change and relative cooling power are evaluated to be 1.53 JKg−1K−1 and 280 JKg−1 for a field change of 7 T, respectively. In addition, inverse MCE is also observed, which might be associated with the first-order magnetic phase transition between two incommensurate longitudinal conical phases.

  18. Ferroelectric and magnetic properties of Aurivillius Bi{sub m+1}Ti{sub 3}Fe{sub m−3}O{sub 3m+3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Tingting, E-mail: jia.tingting@nims.go.jp; Kimura, Hideo, E-mail: KIMURA.Hideo@nims.go.jp [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Cheng, Zhenxiang [Institute for Superconducting and Electronic Materials, University of Wollongong, Squires Way, North Wollongong, New South Wales 2500 (Australia); Zhao, Hongyang [Department of Materials Science and Engineering, Wuhan Institute of Technology, No. 693 Xiongchu Road, Wuhan 430074 (China)

    2015-11-15

    Aurivillius Bi{sub m+1}Ti{sub 3}Fe{sub m−3}O{sub 3m+3} (m = 4, 5, 6) thin films have been deposited by a pulsed laser deposition system. The x-ray diffraction patterns indicate the formation of orthorhombic phase. The remanent polarization (2P{sub r}) of Bi{sub m+1}Ti{sub 3}Fe{sub m−3}O{sub 3m+3} thin films is decreased with the m-number. Positive-up-negative-down measurements indicate the presence of ferroelectric (FE) polarization in as-obtained thin films. Piezoresponse force microscopy investigations confirm the existence of FE domains and the switchable polarization. Weak magnetic moment is detected in the Aurivillius films at room temperature. The present work suggests the possibility of Aurivillius Bi{sub m+1}Ti{sub 3}Fe{sub m−3}O{sub 3m+3} (m = 4, 5, 6) materials as potential room-temperature multiferroics.

  19. Spin reorientation transition and near room-temperature multiferroic properties in a W-type hexaferrite SrZn1.15Co0.85Fe16O27

    International Nuclear Information System (INIS)

    In this Letter, we investigate the magnetic and multiferroic properties of a W-type hexaferrite SrZn1.15Co0.85Fe16O27. Due to the strong planar contribution to the anisotropy provided by Co2+ ions, this hexaferrite shows a spin reorientation transition from easy-axis to easy-cone at 302 K, which is different from the onset temperature of ferroelectric polarization, 275 K. By applying magnetic field, a remarkable drop of polarization is observed, suggesting a large magnetoelectric effect in this multiferroics. The difference between spin reorientation and ferroelectric phase transition temperature as well as the origin of magnetoelectric effect are discussed

  20. Thin Concrete Barrel Vault

    NARCIS (Netherlands)

    Kamerling, M.W.

    2013-01-01

    The paper presents the structural design of a thin barrel vault constructed with Fusée Ceramique infill elements. The load transfer is analyzed and validated. For the structure composed of Fusée Ceramique elements, steel and concrete the stresses are calculated and compared to the stresses given in

  1. Protein Thin Film Machines

    OpenAIRE

    Federici, Stefania; Oliviero, Giulio; Hamad-Schifferli, Kimberly; Bergese, Paolo

    2010-01-01

    We report the first example of microcantilever beams that are reversibly driven by protein thin film machines fuelled by cycling the salt concentration of the surrounding solution. We also show that upon the same salinity stimulus the drive can be completely reversed in its direction by introducing a surface coating ligand. Experimental results are throughout discussed within a general yet simple thermodynamic model.

  2. Thin Wall Iron Castings

    Energy Technology Data Exchange (ETDEWEB)

    J.F. Cuttino; D.M. Stefanescu; T.S. Piwonka

    2001-10-31

    Results of an investigation made to develop methods of making iron castings having wall thicknesses as small as 2.5 mm in green sand molds are presented. It was found that thin wall ductile and compacted graphite iron castings can be made and have properties consistent with heavier castings. Green sand molding variables that affect casting dimensions were also identified.

  3. The ferroelectric and ferromagnetic characterization of CoFe{sub 2}O{sub 4}/Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-PbTiO{sub 3} multilayered thin films

    Energy Technology Data Exchange (ETDEWEB)

    Guo Hongli; Liu Guo; Li Xuedong; Li Haimin [College of Materials Science and engineering, Sichuan University, Chengdu 610064 (China); Zhang Wanli [College of Microelectronics and Solid-State Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zhu Jianguo, E-mail: nic0400@scu.edu.cn [College of Materials Science and engineering, Sichuan University, Chengdu 610064 (China); Xiao Dingquan [College of Materials Science and engineering, Sichuan University, Chengdu 610064 (China)

    2011-05-15

    The multiferroic (PMN-PT/CFO){sub n} (n = 1,2) multilayered thin films have been prepared on SiO{sub 2}/Si(1 0 0) substrate with LNO as buffer layer via a rf magnetron sputtering method. The structure and surface morphology of multilayered thin films were determined by X-ray diffraction (XRD) and atom force microscopy (AFM), respectively. The smooth, dense and crack-free surface shows the excellent crystal quality with root-mean-square (RMS) roughness only 2.9 nm, and average grain size of CFO thin films on the surface is about 44 nm. The influence of the thin films thickness size, periodicity n and crystallite orientation on their properties including ferroelectric, ferromagnetic properties in the (PMN-PT/CFO){sub n} multilayered thin films were investigated. For multilayered thin films with n = 1 and n 2, the remanent polarization Pr are 17.9 {mu}C/cm{sup 2} and 9.9 {mu}C/cm{sup 2}; the coercivity H{sub c} are 1044 Oe and 660 Oe, respectively. In addition, the relative mechanism are also discussed.

  4. Thin film metal-oxides

    CERN Document Server

    Ramanathan, Shriram

    2009-01-01

    Presents an account of the fundamental structure-property relations in oxide thin films. This title discusses the functional properties of thin film oxides in the context of applications in the electronics and renewable energy technologies.

  5. Thin films for material engineering

    Science.gov (United States)

    Wasa, Kiyotaka

    2016-07-01

    Thin films are defined as two-dimensional materials formed by condensing one by one atomic/molecular/ionic species of matter in contrast to bulk three-dimensional sintered ceramics. They are grown through atomic collisional chemical reaction on a substrate surface. Thin film growth processes are fascinating for developing innovative exotic materials. On the basis of my long research on sputtering deposition, this paper firstly describes the kinetic energy effect of sputtered adatoms on thin film growth and discusses on a possibility of room-temperature growth of cubic diamond crystallites and the perovskite thin films of binary compound PbTiO3. Secondly, high-performance sputtered ferroelectric thin films with extraordinary excellent crystallinity compatible with MBE deposited thin films are described in relation to a possible application for thin-film MEMS. Finally, the present thin-film technologies are discussed in terms of a future material science and engineering.

  6. Optical, ferroelectric and magnetic properties of multiferroelectric BiFeO3-(K0.5Na0.5)0.4(Sr 0.6Ba0.4)0.8Nb2O6 thin films

    KAUST Repository

    Yao, Yingbang

    2014-02-01

    Multiferroic BiFeO3-(K0.5Na0.5) 0.4(Sr0.6Ba0.4)0.8Nb 2O6 (BFO-KNSBN) trilayer thin films, were epitaxially grown on MgO(0 0 1) and SrTiO3(0 0 1) by using pulsed laser deposition (PLD). Their ferroelectric, magnetic, dielectric and optical properties were investigated. It was found that both ferroelectric polarization and dielectric constant of the films were enhanced by introducing KNSBN as a barrier layer. Meanwhile, ferromagnetism of BFO was maintained. More interestingly, a double hysteresis magnetic loop was observed in the KNSBN-BFO-KNSBN trilayer films, where exchange bias and secondary phase in the BFO layer played crucial roles. Interactions between adjacent layers were revealed by temperature-dependent Raman spectroscopic measurements. © 2013 Elsevier B.V. All rights reserved.

  7. Terahertz and infrared studies of antiferroelectric phase transition in multiferroic Bi.sub.0.85./sub.Nd.sub.0.15./sub.FeO.sub.3./sub..

    Czech Academy of Sciences Publication Activity Database

    Goian, Veronica; Kamba, Stanislav; Greicius, S.; Nuzhnyy, Dmitry; Karimi, S.; Reaney, I. M.

    2011-01-01

    Roč. 110, č. 7 (2011), 074112/1-074112/5. ISSN 0021-8979 R&D Projects: GA ČR GD202/09/H041; GA ČR(CZ) GA202/09/0682 Grant ostatní: GA UK(CZ) SVV-2011-263303 Institutional research plan: CEZ:AV0Z10100520 Keywords : multiferroics * infrared and THz spectroscopy * phonons * antiferroelectrics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.168, year: 2011

  8. Heterogeneity in Polymer Thin Films

    OpenAIRE

    Kanaya, Toshiji; Inoue, Rintaro; Nishida, Koji

    2011-01-01

    In the last two decades very extensive studies have been performed on polymer thin films to reveal very interesting but unusual properties. One of the most interesting findings is the decrease in glass transition temperature Tg with film thickness in polystyrene (PS) thin film supported on Si substrate. Another interesting finding is apparent negative thermal expansivity in glassy state for thin films below ∼25 nm. In order to understand the unusual properties of polymer thin films we have st...

  9. Rare Earth Oxide Thin Films

    CERN Document Server

    Fanciulli, Marco

    2007-01-01

    Thin rare earth (RE) oxide films are emerging materials for microelectronic, nanoelectronic, and spintronic applications. The state-of-the-art of thin film deposition techniques as well as the structural, physical, chemical, and electrical properties of thin RE oxide films and of their interface with semiconducting substrates are discussed. The aim is to identify proper methodologies for the development of RE oxides thin films and to evaluate their effectiveness as innovative materials in different applications.

  10. Photovoltaic effect and enhanced magnetization in 0.9(BiFeO3)–0.1(YCrO3) composite thin film fabricated using sequential pulsed laser deposition

    International Nuclear Information System (INIS)

    We report on the photovoltaic effect and multiferroic properties of a 0.9(BiFeO3)–0.1(YCrO3) composite thin film deposited on a Pt/TiO2/SiO2/Si substrate by sequential ablation of BiFeO3 and YCrO3 ceramic targets using pulsed laser deposition. The desired composition of the composite was achieved by controlling the ablation time of respective targets. As confirmed by the x-ray diffraction pattern the resultant film was found to be polycrystalline in nature and composed of a mixture of both rhombohedral BiFeO3 and orthorhombic YCrO3 phases. Interesting multiferroic properties in terms of an enhanced saturation magnetization of ∼14 emu cm−3 and the remnant polarization of ∼4.5 µC cm−2 were observed where the enhancement in magnetization as compared to pristine BiFeO3 could be attributed to the super-exchange interaction between Fe and Cr-ions. The photovoltaic properties of the composite thin film were studied under white light illumination in both top–bottom and lateral electrode configurations. Short circuit current densities (JSC) = 1.48 µA cm−2 and 0.44 µA cm−2, and open circuit voltages (VOC) = 0.51 V and 0.32 V were observed in top–bottom and lateral electrode configurations, respectively. (paper)

  11. Thin Film Microbatteries

    International Nuclear Information System (INIS)

    Thin film batteries are built layer by layer by vapor deposition. The resulting battery is formed of parallel plates, much as an ordinary battery construction, just much thinner. The figure (Fig. 1) shows an example of a thin film battery layout where films are deposited symmetrically onto both sides of a supporting substrate. The full stack of films is only 10 to 15 (micro)m thick, but including the support at least doubles the overall battery thickness. When the support is thin, the entire battery can be flexible. At least six companies have commercialized or are very close to commercializing such all-solid-state thin film batteries and market research predicts a growing market and a variety of applications including sensors, RFID tags, and smarter cards. In principle with a large deposition system, a thin film battery might cover a square meter, but in practice, most development is targeting individual cells with active areas less than 25 cm2. For very small battery areas, 2, microfabrication processes have been developed. Typically the assembled batteries have capacities from 0.1 to 5 mAh. The operation of a thin film battery is depicted in the schematic diagram (Fig. 2). Very simply, when the battery is allowed to discharge, a Li+ ion migrates from the anode to the cathode film by diffusing through the solid electrolyte. When the anode and cathode reactions are reversible, as for an intercalation compound or alloy, the battery can be recharged by reversing the current. The difference in the electrochemical potential of the lithium determines the cell voltage. Most of the thin films used in current commercial variations of this thin film battery are deposited in vacuum chambers by RF and DC magnetron sputtering and by thermal evaporation onto unheated substrates. In addition, many publications report exploring a variety of other physical and chemical vapor deposition processes, such as pulsed laser deposition, electron cyclotron resonance sputtering, and

  12. Biomimetic thin film deposition

    Energy Technology Data Exchange (ETDEWEB)

    Rieke, P.R.; Graff, G.E.; Campbell, A.A.; Bunker, B.C.; Baskaran, S.; Song, L.; Tarasevich, B.J.; Fryxell, G.E.

    1995-09-01

    Biological mineral deposition for the formation of bone, mollusk shell and other hard tissues provides materials scientists with illustrative materials processing strategies. This presentation will review the key features of biomineralization and how these features can be of technical importance. We have adapted existing knowledge of biomineralization to develop a unique method of depositing inorganic thin films and coating. Our approach to thin film deposition is to modify substrate surfaces to imitate the proteins found in nature that are responsible for controlling mineral deposition. These biomimetic surfaces control the nucleation and growth of the mineral from a supersaturated aqueous solution. This has many processing advantages including simple processing equipment, environmentally benign reagents, uniform coating of highly complex shapes, and enhanced adherence of coating. Many different types of metal oxide, hydroxide, sulfide and phosphate materials with useful mechanical, optical, electronic and biomedical properties can be deposited.

  13. Effects of NiFe{sub 2}O{sub 4} on magnetoelectric coupling effect of BiFeO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Jianjun [Department of Physics, Hebei Normal University for Nationalities, Chengde 067000 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050016 (China); Yang, Shumin; Yang, Wei; Qi, Yunkai; Zhao, Guoliang [Department of Physics, Hebei Normal University for Nationalities, Chengde 067000 (China); Sun, Huiyuan, E-mail: huiyuansun@126.com [College of Physics Science and Information Engineering, Hebei Normal University, Shijiazhuang 050016 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050016 (China)

    2014-01-15

    Multiferroic composite thin films with composition (1−x)BiFeO{sub 3}–xNiFe{sub 2}O{sub 4} (x=0.00, 0.10, 0.15, 0.20, 0.25, and 0.30) were prepared by chemical solution deposition(CSD). The results show that with increasing x, the average size of the crystal grains of BiFeO{sub 3} diminishes gradually, and the leakage current density in composite thin films decreases while the remnant polarizations increases. The calculated results for the ferromagnetic contribution of the NiFe{sub 2}O{sub 4} indicated that BiFeO{sub 3} also contributed magnetic moment to the composite films. On comparing the grain sizes and magnetic measurement results of the composite thin films with x=0.20 and 0.25, we found that the decreasing crystal grain size of the BiFeO{sub 3} was responsible for ferromagnetism and that the enhanced magnetoelectric coupling effect in composite thin films was also an important factor. - Highlights: • With increasing x, the average size of the crystal grains of BiFeO{sub 3} diminishes gradually. • With increasing x, the leakage current density in composite thin films decreases while the remnant polarization increases. • The calculated results indicated that BiFeO{sub 3} also contributed magnetic moment to the composite films. • The decreasing crystal grain size of the BiFeO{sub 3} was responsible for ferromagnetism and the enhanced magnetoelectric coupling effect.

  14. Thin film superconductor magnetic bearings

    Science.gov (United States)

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  15. Thin film processes

    CERN Document Server

    Vossen, John L

    1978-01-01

    Remarkable advances have been made in recent years in the science and technology of thin film processes for deposition and etching. It is the purpose of this book to bring together tutorial reviews of selected filmdeposition and etching processes from a process viewpoint. Emphasis is placed on the practical use of the processes to provide working guidelines for their implementation, a guide to the literature, and an overview of each process.

  16. Evaporated VOx Thin Films

    Science.gov (United States)

    Stapinski, Tomasz; Leja, E.

    1989-03-01

    VOx thin films on glass were obtained by thermal evaporation of V205, powder. The structural investigations were carried out with the use of X-ray diffractometer. The electrical properties of the film were examined by means of temperature measurements of resistivity for the samples heat-treated in various conditions. Optical transmission and reflection spectra of VOX films of various composition showed the influence of the heat treatment.

  17. Photovoltaics. Thin future?

    International Nuclear Information System (INIS)

    Since the year 2000, Germany has operated a tariff system to encourage development of renewable energy sources and one of the results has been an increase in the country's PV market from 12 MWp in 1999 to 600 MWp in 2005. Other states have followed the German example and details are given. But, many of these other states operate a capping programme that restricts growth. At present, Germany has by far the greatest share of both the world and the European markets.Trends for small-scale and residential PV systems for Europe and trends in large-scale systems in Europe are discussed and the key differences highlighted. The future impact of the higher efficiency thin-film modules on low-efficiency crystalline modules is discussed. Not only will the thin film types be cheaper, they will also offer reductions on the BOS (balance-of-system) level by about the year 2010. The reasons why the BOS cost savings in large-scale systems are higher than for roof-top systems is explained. In southern Europe, thin film modules have the additional benefit of a low power temperature factor and therefore a higher yield per kWp

  18. Thin film scintillators

    Science.gov (United States)

    McDonald, Warren; McKinney, George; Tzolov, Marian

    2015-03-01

    Scintillating materials convert energy flux (particles or electromagnetic waves) into light with spectral characteristic matching a subsequent light detector. Commercial scintillators such as yttrium aluminum garnet (YAG) and yttrium aluminum perovskite (YAP) are commonly used. These are inefficient at lower energies due to the conductive coating present on their top surface, which is needed to avoid charging. We hypothesize that nano-structured thin film scintillators will outperform the commercial scintillators at low electron energies. We have developed alternative thin film scintillators, zinc tungstate and zinc oxide, which show promise for higher sensitivity to lower energy electrons since they are inherently conductive. Zinc tungstate films exhibit photoluminescence quantum efficiency of 74%. Cathodoluminescence spectroscopy was applied in transmission and reflection geometries. The comparison between the thin films and the YAG and YAP commercial scintillators shows much higher light output from the zinc tungstate and zinc oxide at electron energies less than 5 keV. Our films were integrated in a backscattered electron detector. This detector delivers better images than an identical detector with commercial YAG scintillator at low electron energies. Dr. Nicholas Barbi from PulseTor LLC, Dr. Anura Goonewardene, NSF Grants: #0806660, #1058829, #0923047.

  19. Thin shell model revisited

    CERN Document Server

    Gao, Sijie

    2014-01-01

    We reconsider some fundamental problems of the thin shell model. First, we point out that the "cut and paste" construction does not guarantee a well-defined manifold because there is no overlap of coordinates across the shell. When one requires that the spacetime metric across the thin shell is continuous, it also provides a way to specify the tangent space and the manifold. Other authors have shown that this specification leads to the conservation laws when shells collide. On the other hand, the well-known areal radius $r$ seems to be a perfect coordinate covering all regions of a spherically symmetric spacetime. However, we show by simple but rigorous arguments that $r$ fails to be a coordinate covering a neighborhood of the thin shell if the metric across the shell is continuous. When two spherical shells collide and merge into one, we show that it is possible that $r$ remains to be a good coordinate and the conservation laws hold. To make this happen, different spacetime regions divided by the shells must...

  20. Quantification of strain and charge co-mediated magnetoelectric coupling on ultra-thin Permalloy/PMN-PT interface.

    Science.gov (United States)

    Nan, Tianxiang; Zhou, Ziyao; Liu, Ming; Yang, Xi; Gao, Yuan; Assaf, Badih A; Lin, Hwaider; Velu, Siddharth; Wang, Xinjun; Luo, Haosu; Chen, Jimmy; Akhtar, Saad; Hu, Edward; Rajiv, Rohit; Krishnan, Kavin; Sreedhar, Shalini; Heiman, Don; Howe, Brandon M; Brown, Gail J; Sun, Nian X

    2014-01-01

    Strain and charge co-mediated magnetoelectric coupling are expected in ultra-thin ferromagnetic/ferroelectric multiferroic heterostructures, which could lead to significantly enhanced magnetoelectric coupling. It is however challenging to observe the combined strain charge mediated magnetoelectric coupling, and difficult in quantitatively distinguish these two magnetoelectric coupling mechanisms. We demonstrated in this work, the quantification of the coexistence of strain and surface charge mediated magnetoelectric coupling on ultra-thin Ni0.79Fe0.21/PMN-PT interface by using a Ni0.79Fe0.21/Cu/PMN-PT heterostructure with only strain-mediated magnetoelectric coupling as a control. The NiFe/PMN-PT heterostructure exhibited a high voltage induced effective magnetic field change of 375 Oe enhanced by the surface charge at the PMN-PT interface. Without the enhancement of the charge-mediated magnetoelectric effect by inserting a Cu layer at the PMN-PT interface, the electric field modification of effective magnetic field was 202 Oe. By distinguishing the magnetoelectric coupling mechanisms, a pure surface charge modification of magnetism shows a strong correlation to polarization of PMN-PT. A non-volatile effective magnetic field change of 104 Oe was observed at zero electric field originates from the different remnant polarization state of PMN-PT. The strain and charge co-mediated magnetoelectric coupling in ultra-thin magnetic/ferroelectric heterostructures could lead to power efficient and non-volatile magnetoelectric devices with enhanced magnetoelectric coupling. PMID:24418911

  1. Superfast Thinning of a Nanoscale Thin Liquid Film

    OpenAIRE

    Winkler, Michael; Kofod, Guggi; Krastev, Rumen; Abel, Markus

    2011-01-01

    This fluid dynamics video demonstrates an experiment on superfast thinning of a freestanding thin aqueous film. The production of such films is of fundamental interest for interfacial sciences and the applications in nanoscience. The stable phase of the film is of the order $5-50\\,nm$; nevertheless thermal convection can be established which changes qualitatively the thinning behavior from linear to exponentially fast. The film is thermally driven on one spot by a very cold needle, establishi...

  2. Carbon thin film thermometry

    Science.gov (United States)

    Collier, R. S.; Sparks, L. L.; Strobridge, T. R.

    1973-01-01

    The work concerning carbon thin film thermometry is reported. Optimum film deposition parameters were sought on an empirical basis for maximum stability of the films. One hundred films were fabricated for use at the Marshall Space Flight Center; 10 of these films were given a precise quasi-continuous calibration of temperature vs. resistance with 22 intervals between 5 and 80 K using primary platinum and germanium thermometers. Sensitivity curves were established and the remaining 90 films were given a three point calibration and fitted to the established sensitivity curves. Hydrogen gas-liquid discrimination set points are given for each film.

  3. Thin Concrete Barrel Vault

    OpenAIRE

    Kamerling, M.W.

    2013-01-01

    The paper presents the structural design of a thin barrel vault constructed with Fusée Ceramique infill elements. The load transfer is analyzed and validated. For the structure composed of Fusée Ceramique elements, steel and concrete the stresses are calculated and compared to the stresses given in the codes used from 1950 to the present. The advantages and disadvantages of these low rise barrel vaults are showed. Further the possibilities of a light infill to reduce, for structures of concre...

  4. Polycrystalline thin film photovoltaic technology

    Energy Technology Data Exchange (ETDEWEB)

    Ullal, H.S.; Zweibel, K.; Mitchell, R.L.; Noufi, R.

    1991-03-01

    Low-cost, high-efficiency thin-film modules are an exciting photovoltaic technology option for generating cost-effective electricity in 1995 and beyond. In this paper we review the significant technical progress made in the following thin films: copper indium diselenide, cadmium telluride, and polycrystalline thin silicon films. Also, the recent US DOE/SERI initiative to commercialize these emerging technologies is discussed. 6 refs., 9 figs.

  5. Thin-Film Power Transformers

    Science.gov (United States)

    Katti, Romney R.

    1995-01-01

    Transformer core made of thin layers of insulating material interspersed with thin layers of ferromagnetic material. Flux-linking conductors made of thinner nonferromagnetic-conductor/insulator multilayers wrapped around core. Transformers have geometric features finer than those of transformers made in customary way by machining and mechanical pressing. In addition, some thin-film materials exhibit magnetic-flux-carrying capabilities superior to those of customary bulk transformer materials. Suitable for low-cost, high-yield mass production.

  6. Synthesis of BiFeO3 thin films on single-terminated Nb : SrTiO3 (111 substrates by intermittent microwave assisted hydrothermal method

    Directory of Open Access Journals (Sweden)

    Ivan Velasco-Davalos

    2016-06-01

    Full Text Available We report on a simple and fast procedure to create arrays of atomically flat terraces on single crystal SrTiO3 (111 substrates and the deposition of ferroelectric BiFeO3 thin films on such single-terminated surfaces. A microwave-assisted hydrothermal method in deionized water and ammonia solution selectively removes either (SrO34− or Ti4+ layers to ensure the same chemical termination on all terraces. Measured step heights of 0.225 nm (d111 and uniform contrast in the phase image of the terraces confirm the single termination in pure and Nb doped SrTiO3 single crystal substrates. Multiferroic BiFeO3 thin films were then deposited by the same microwave assisted hydrothermal process on Nb : SrTiO3 (111 substrates. Bi(NO33 and Fe(NO33 along with KOH served as the precursors solution. Ferroelectric behavior of the BiFeO3 films on Nb : SrTiO3 (100 substrates was verified by piezoresponse force microscopy.

  7. Synthesis of BiFeO3 thin films on single-terminated Nb : SrTiO3 (111) substrates by intermittent microwave assisted hydrothermal method

    Science.gov (United States)

    Velasco-Davalos, Ivan; Ambriz-Vargas, Fabian; Kolhatkar, Gitanjali; Thomas, Reji; Ruediger, Andreas

    2016-06-01

    We report on a simple and fast procedure to create arrays of atomically flat terraces on single crystal SrTiO3 (111) substrates and the deposition of ferroelectric BiFeO3 thin films on such single-terminated surfaces. A microwave-assisted hydrothermal method in deionized water and ammonia solution selectively removes either (SrO3)4- or Ti4+ layers to ensure the same chemical termination on all terraces. Measured step heights of 0.225 nm (d111) and uniform contrast in the phase image of the terraces confirm the single termination in pure and Nb doped SrTiO3 single crystal substrates. Multiferroic BiFeO3 thin films were then deposited by the same microwave assisted hydrothermal process on Nb : SrTiO3 (111) substrates. Bi(NO3)3 and Fe(NO3)3 along with KOH served as the precursors solution. Ferroelectric behavior of the BiFeO3 films on Nb : SrTiO3 (100) substrates was verified by piezoresponse force microscopy.

  8. Induced ferromagnetism and magnetoelectric coupling in ion-beam synthesized BiFeO3–CoFe2O4 nanocomposite thin films

    Science.gov (United States)

    Modarresi, H.; Lazenka, V.; Menéndez, E.; Lorenz, M.; Bisht, M.; Volodin, A.; Van Haesendonck, C.; Grundmann, M.; Van Bael, M. J.; Temst, K.; Vantomme, A.

    2016-08-01

    Ferrimagnetic CoFe2O4 (cobalt ferrite) is formed within an epitaxial BiFeO3 (bismuth ferrite) thin film matrix by Co channeled ion implantation and subsequent annealing. The presence of nanoscale CoFe2O4 crystals in the matrix is confirmed by x-ray diffraction using synchrotron radiation. The significantly increased magnetic moment and the low-temperature coercive field of the composite system evidence the formation of ferrimagnetic cobalt ferrite and its nanoscale character, respectively. The results demonstrate that ion beam synthesis is an appropriate method to controllably transform a planar system into a granular one, increasing the interface area between cobalt ferrite and bismuth ferrite. The ferroelectric nature of the BiFeO3–CoFe2O4 composite is confirmed by several scanning probe microscopy techniques. At room temperature, the composite exhibits a magnetoelectric voltage coefficient of α ME  =  17.5 V (cm · Oe)‑1, while a single-phase BiFeO3 thin film shows a α ME value of 4.2 V (cm · Oe)‑1. The high magnetoelectric voltage coefficient is interpreted to be the result of the interfacial interaction between the ferrimagnetic CoFe2O4 nanocrystallites and the multiferroic BiFeO3 matrix.

  9. Growth and characterization of La1-xCaxMnO3 thin films with different Ca concentrations using PLD with in-situ RHEED

    International Nuclear Information System (INIS)

    The growth of doped perovskite manganites is interesting for both basic research and potential applications. These materials, which show the colossal magnetoresistance effect, have promise for new sensor applications, in particular as layers in multiferroic superlattices. Using pulsed laser deposition (PLD), La1-xCaxMnO3 (LCMO) thin films were grown. All targets were prepared by standard ceramic synthesis. As substrates SrTiO3(100) and NdGaO3(110) are used. The surface of the SrTiO3 substrates is atomically flat and TiO2 terminated after chemical and subsequent annealing treatment. To obtain atomically flat and single terminated NdGaO3 surfaces an annealing treatment is applied. The growth of the films is monitored by in-situ reflection high energy electron diffraction (RHEED). The characterization is supplemented by X-ray diffraction and atomic force microscopy. The LCMO films were grown with five different Ca concentrations between 33 % and 50 %. Optimal growth conditions lead to high quality crystalline magnetic films with rms roughnesses below 1nm for layer thicknesses up to 500 nm. The influence of the Ca concentration, the substrate and the film thickness on the properties of the thin films is analyzed

  10. Nanoscale study of perovskite BiFeO3/spinel (Fe,Zn)3O4 co-deposited thin film by electrical scanning probe methods

    International Nuclear Information System (INIS)

    Highlights: • A BFO/FZO sample has been prepared using PLD and investigated by SPM techniques. • SPM/HAADF-STEM images have allowed to understand the sample physical properties. • Without destructive material methods we were able to distinguish BFO and FZO. - Abstract: For this study, a BiFeO3 (BFO) perovskite/(Fe,Zn)3O4 (FZO) spinel sample grown on SrTiO3:Nb (0 0 1) has been prepared using pulsed laser deposition with a single target composition of (Bi1.1FeO3)0.65(Fe2.2Zn0.8O4)0.35. The nanoscale electrical properties of ferroelectric BFO/semi-conducting FZO thin film have been investigated using piezoresponse force microscopy (PFM) and conductive-atomic force microscopy (C-AFM). Scanning probe methods reveal that BFO grows as nano-islets with a complex structure which is coherent with the cross-sectional high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images. The comparison between nanoscale electrical techniques and HAADF-STEM images have allowed to understand the origin of the different physical properties of the multiferroic/magnetoconductive co-deposited thin film at the nanoscale. By using PFM/C-AFM techniques, we were able to fully distinguish BFO and FZO materials in the nanostructured sample without using destructive material characterization methods

  11. High Power Thin Disk Laser

    OpenAIRE

    Giesen, Adolf

    2011-01-01

    In this talk, the latest results for thin disk lasers will be presented. Thin disk lasers can be operated in cw-mode as well as in pulsed mode with pulse durations from 100 fs to microseconds. Results from different institutes and companies will be shown demonstrating the power/energy scalability of the thin disk laser design with good beam quality and high efficiency, simultaneously. Several German companies are selling thin disk lasers with up to 16 kW output power (cw) and with up to 1 kW...

  12. Handbook of thin film technology

    CERN Document Server

    Frey, Hartmut

    2015-01-01

    “Handbook of Thin Film Technology” covers all aspects of coatings preparation, characterization and applications. Different deposition techniques based on vacuum and plasma processes are presented. Methods of surface and thin film analysis including coating thickness, structural, optical, electrical, mechanical and magnetic properties of films are detailed described. The several applications of thin coatings and a special chapter focusing on nanoparticle-based films can be found in this handbook. A complete reference for students and professionals interested in the science and technology of thin films.

  13. Physics of thin films

    Energy Technology Data Exchange (ETDEWEB)

    Francombe, M.H. (Dept. of Physics, Univ. of Pittsburgh, Pittsburgh, PA (US)); Vossen, J.L. (John Vossen Associates, Technical and Scientific Consulting, Bridgewater, NJ (US))

    1992-01-01

    This book of Physics of Thin Films emphasizes two main technical themes. The first is essentially an extension of the topical thrust on Thin Films for Advance Electronic Devices, developed in Volume 15 of this series. The second deals primarily with the physical and mechanical behavior of films and the influence of these in relation to various applications. The first of the four articles in this volume, by Neelkanth G. Dhere, discusses high-transition-temperature (T{sub c}) superconducting films. Since their discovery in 1986, both world-wide research activity and published literature on high-T{sub c} oxide films have exploded at a phenomenal rate. In his treatment, the author presents an effective survey of the already vast literature on this subject, discusses the numerous techniques under development for the growth of these perovskite-related complex oxides, and describes their key properties and applications. In particular, factors affecting the epitaxial structure, critical current capability, and microwave conductivity in Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O based film compositions are evaluated in relation to their use at 77K. An overview of potential applications in a variety of microwave devices, wide-band optical detectors, SQUID-type high-sensitivity magnetometers, etc., is included.

  14. Physics of thin films

    International Nuclear Information System (INIS)

    This book of Physics of Thin Films emphasizes two main technical themes. The first is essentially an extension of the topical thrust on Thin Films for Advance Electronic Devices, developed in Volume 15 of this series. The second deals primarily with the physical and mechanical behavior of films and the influence of these in relation to various applications. The first of the four articles in this volume, by Neelkanth G. Dhere, discusses high-transition-temperature (Tc) superconducting films. Since their discovery in 1986, both world-wide research activity and published literature on high-Tc oxide films have exploded at a phenomenal rate. In his treatment, the author presents an effective survey of the already vast literature on this subject, discusses the numerous techniques under development for the growth of these perovskite-related complex oxides, and describes their key properties and applications. In particular, factors affecting the epitaxial structure, critical current capability, and microwave conductivity in Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O based film compositions are evaluated in relation to their use at 77K. An overview of potential applications in a variety of microwave devices, wide-band optical detectors, SQUID-type high-sensitivity magnetometers, etc., is included

  15. Thin-film microextraction.

    Science.gov (United States)

    Bruheim, Inge; Liu, Xiaochuan; Pawliszyn, Janusz

    2003-02-15

    The properties of a thin sheet of poly(dimethylsiloxane) (PDMS) membrane as an extraction phase were examined and compared to solid-phase microextraction (SPME) PDMS-coated fiber for application to semivolatile analytes in direct and headspace modes. This new PDMS extraction approach showed much higher extraction rates because of the larger surface area to extraction-phase volume ratio of the thin film. Unlike the coated rod formats of SPME using thick coatings, the high extraction rate of the membrane SPME technique allows larger amounts of analytes to be extracted within a short period of time. Therefore, higher extraction efficiency and sensitivity can be achieved without sacrificing analysis time. In direct membrane SPME extraction, a linear relationship was found between the initial rate of extraction and the surface area of the extraction phase. However, for headspace extraction, the rates were somewhat lower because of the resistance to analyte transport at the sample matrix/headspace barrier. It was found that the effect of this barrier could be reduced by increasing either agitation, temperature, or surface area of the sample matrix/headspace interface. A method for the determination of PAHs in spiked lake water samples was developed based on the membrane PDMS extraction coupled with GC/MS. A linearity of 0.9960 and detection limits in the low-ppt level were found. The reproducibility was found to vary from 2.8% to 10.7%. PMID:12622398

  16. Thin film mechanics

    Science.gov (United States)

    Cooper, Ryan C.

    This doctoral thesis details the methods of determining mechanical properties of two classes of novel thin films suspended two-dimensional crystals and electron beam irradiated microfilms of polydimethylsiloxane (PDMS). Thin films are used in a variety of surface coatings to alter the opto-electronic properties or increase the wear or corrosion resistance and are ideal for micro- and nanoelectromechanical system fabrication. One of the challenges in fabricating thin films is the introduction of strains which can arise due to application techniques, geometrical conformation, or other spurious conditions. Chapters 2-4 focus on two dimensional materials. This is the intrinsic limit of thin films-being constrained to one atomic or molecular unit of thickness. These materials have mechanical, electrical, and optical properties ideal for micro- and nanoelectromechanical systems with truly novel device functionality. As such, the breadth of applications that can benefit from a treatise on two dimensional film mechanics is reason enough for exploration. This study explores the anomylously high strength of two dimensional materials. Furthermore, this work also aims to bridge four main gaps in the understanding of material science: bridging the gap between ab initio calculations and finite element analysis, bridging the gap between ab initio calculations and experimental results, nanoscale to microscale, and microscale to mesoscale. A nonlinear elasticity model is used to determine the necessary elastic constants to define the strain-energy density function for finite strain. Then, ab initio calculations-density functional theory-is used to calculate the nonlinear elastic response. Chapter 2 focuses on validating this methodology with atomic force microscope nanoindentation on molybdenum disulfide. Chapter 3 explores the convergence criteria of three density functional theory solvers to further verify the numerical calculations. Chapter 4 then uses this model to investigate

  17. Investigation on Silicon Thin Film Solar Cells

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The preparation, current status and trends are investigated for silicon thin film solar cells. The advantages and disadvantages of amorphous silicon thin film, polycrystalline silicon thin film and mono-crystalline silicon thin film solar cells are compared. The future development trends are pointed out. It is found that polycrystalline silicon thin film solar cells will be more promising for application with great potential.

  18. Effect of doping of vanadium ions on crystal structure, dielectric and magnetic properties of Bi0.8Ba0.2FeO3 multiferroic

    Science.gov (United States)

    Godara, Priyanka; Agarwal, Ashish; Ahlawat, Neetu; Sanghi, Sujata; Kaswan, Kavita

    2016-05-01

    Synthesis of Bi0.8Ba0.2Fe1-xVxO3 multiferroics (with x=0.0, 0.02 and 0.04 having code V0, V2 and V4, respectively) have been done by solid-state reaction technique. The structural, magnetic and electrical characterization of the prepared ceramics have been carried out using X-ray diffraction, Vibrating sample magnetometry and impedance spectroscopy, respectively. Rietveld refinement studies show that all samples have rhombohedral structure (R3c). The observed lattice distortion is due to the difference in the ionic radii of parent ions and doped ions. Sizeable M-H hysteresis loops revealed the transformation of antiferromagnetic BiFeO3 (BFO) into ferromagnetic with Ba and V addition. The highest values of coercive field ~4.5 kOe and saturation magnetization ~1.14 emu/g are observed for V0 and V2 samples, respectively. The dielectric properties were improved with the co-doping as compared with the pure BFO compound due to structural distortion and decrease of oxygen vacancies by addition of higher valence V5+ cation.

  19. Antiferromagnetic spin glass-like behavior in sintered multiferroic Aurivillius Bim+1Ti3Fem-3O3m+3 compounds

    Science.gov (United States)

    Jartych, E.; Pikula, T.; Mazurek, M.; Lisinska-Czekaj, A.; Czekaj, D.; Gaska, K.; Przewoznik, J.; Kapusta, C.; Surowiec, Z.

    2013-09-01

    The structure, hyperfine interactions and magnetic properties of the series of multiferroic Bim+1Ti3Fem-3O3m+3 Aurivillius compounds with m=4-8 were studied using X-ray diffraction, 57Fe Mössbauer spectroscopy and vibrating sample magnetometry. Samples were prepared by the conventional solid-state sintering method. Bulk magnetic measurements showed that for m=4 the compound is paramagnetic down to 2 K while in the compound with m=5 the antiferromagnetic type transition was observed at 11 K. In the case of compounds with m=6-8 much more complex magnetic behavior was found. For these compounds a gradual spin freezing and antiferromagnetic spin glass-like ordering were observed on decreasing temperature. The temperature of spin glass freezing was determined as 260, 280 and 350 K for m=6, 7 and 8, respectively. Room-temperature Mössbauer spectra of all the compounds studied confirm their paramagnetic state. However, liquid nitrogen and liquid helium temperature measurements reveal magnetic ordering with a residual paramagnetic phase contribution for the compounds with m=5-8.

  20. Superspin glass phase and hierarchy of interactions in multiferroic PbFe1/2Sb1/2O3: an analog of ferroelectric relaxors?

    International Nuclear Information System (INIS)

    We have fabricated new perovskite multiferroic PbFe1/2Sb1/2O3 with a high degree (up to 0.9) of chemical ordering and unexpectedly high-temperature magnetic relaxor properties, which can barely be described within concepts of conventional spin glass physics. Notably, we found that the field-temperature phase diagram of this material, in the extremely wide temperature interval, contains the de Almeida–Thouless-type critical line, which has been the subject of long debates regarding its possible experimental realization. We explain our findings by the creation, at high temperatures of not less than 250 K, of giant superspins (SSs), owing, curiously enough, to the antiferromagnetic superexchange interaction. We show that these SSs are capable of strong high-temperature magnetic relaxation in the relaxor phase, down to about 150 K, where they transform into a SS glass phase. On further cooling, the material experiences another striking transition, this time, into an ordinary (single-spin) antiferromagnetic phase. We comprehensively analyze the above complex physical picture in terms of three complimentary theoretical approaches. Namely, the ab initio calculations elucidate the microscopic mechanism of giant SS formation, the high-temperature expansion accounts for the morphology of these clusters, and the random field approach provides the description of disorder-related characteristics. (paper)

  1. Magnetic resonance and spin-reorientation transitions in Nd0,75Ho0,25Fe3(BO3)4 multiferroic

    International Nuclear Information System (INIS)

    The experimental data on high frequency resonant properties of multiferroic Nd0,75Ho0,25Fe3(BO3)4 investigated by the antiferromagnetic resonance method (AFMR) in wide frequency and temperature ranges are presented. The influence of substitution of Ho3+ ions for Nd3+ ones on resonant properties of Nd0,75Ho0,25Fe3(BO3)4 solid solution was studied. The peculiarities of field-induced spin-reorientation phase transitions for directions H || c and H || a are considered. For these directions the magnetic anisotropy changes from ''easy axies'' anisotropy to ''easy plane'' one. The AFMR modes of the Fe3+subsystem were revealed. New information about the main AFMR characteristics was obtained. It is shown that dominant in this compound is the ''easy plane'' anisotropy with a week anisotropy in the basal plane. It is for the first time that some specific features were observed in the AFMR spectra that were supposed to be due to a space-modulated spin structure (incommensurate phase) in the Nd0,75Ho0,25Fe3(BO3)4

  2. Multiferroic behavior on nanometric La2/3Ca1/3MnO3 / BaTiO3 bilayers

    Science.gov (United States)

    Prieto, Pedro; Ordoñez, John Edward; Gomez, Maria Elena; Lopera, Wilson

    2014-03-01

    We have deposited bilayers of the FM La2/3Ca1/3MnO3 and FE BaTiO3 as a route to design systems with artificial magnetoelectric coupling on LCMO/BTO/Nb:STO system. We maintain a fixed magnetic layer thickness (tLCMO = 48 nm) and varying the thickness of the ferroelectric layer (tBTO = 20, 50, 100 nm). We analyze the influence of the thickness ratio (tBTO/ tLCMO) in electrical and magnetic properties of manganite. From X-ray diffraction analysis we observed that the samples grew textured. Magnetization and transport measurements indicate a possible multiferroic behavior in the bilayer. We found an increase in the Curie and metal-insulator transition temperature in the bilayer in comparison with those for LCMO (48nm)/STO. Hysteresis loops on bilayers show ferromagnetic behavior. This work has been supported by the ``El Patrimonio Autónomo Fondo Nacional de Financiamiento para CT&I FJC'' Colciencias-CENM Research Projects: No. 1106-48-925531 and CI7917-CC 10510 contract 0002-2013 COLCIENCIAS-UNIVALLE.

  3. Magnetic field-induced ferroelectric domain structure evolution and magnetoelectric coupling for [110]-oriented PMN-PT/Terfenol-D multiferroic composites

    Science.gov (United States)

    Fang, F.; Jing, W. Q.

    2016-01-01

    Magnetic field-induced polarization rotation and magnetoelectric coupling effects are studied for [110]-oriented (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3/Tb0.3Dy0.7Fe2(PMN-xPT/Terfenol-D) multiferroic composites. Two compositions of the [110]-oriented relaxor ferroelectric single crystals, PMN-28PT and PMN-33PT, are used. In [110]-oriented PMN-28PT, domains of rhombohedral (R) and monoclinic (MB) phases coexist prior to the magnetic loadings. Upon the applied magnetic loadings, phase transition from monoclinic MB to R phase occurs. In [110]-oriented PMN-33PT, domains are initially of mixed orthorhombic (O) and MB phases, and the phase transition from O to MB phase takes place upon the external magnetic loading. Compared to PMN-28PT, the PMN-33PT single crystal exhibits much finer domain boundary structure prior to the magnetic loadings. Upon the magnetic loadings, more domain variants are induced via the phase transition in PMN-33PT than that in PMN-28PT single crystal. The finer domain band structure and more domain variants contribute to stronger piezoelectric activity. As a result, the composite of PMN-33PT/Terfenol-D manifests a stronger ME coupling than PMN-28PT/Terfenol-D composite.

  4. Magnetic field-induced ferroelectric domain structure evolution and magnetoelectric coupling for [110]-oriented PMN-PT/Terfenol-D multiferroic composites

    Directory of Open Access Journals (Sweden)

    F. Fang

    2016-01-01

    Full Text Available Magnetic field-induced polarization rotation and magnetoelectric coupling effects are studied for [110]-oriented (1-xPb(Mg1/3Nb2/3O3-xPbTiO3/Tb0.3Dy0.7Fe2(PMN-xPT/Terfenol-D multiferroic composites. Two compositions of the [110]-oriented relaxor ferroelectric single crystals, PMN-28PT and PMN-33PT, are used. In [110]-oriented PMN-28PT, domains of rhombohedral (R and monoclinic (MB phases coexist prior to the magnetic loadings. Upon the applied magnetic loadings, phase transition from monoclinic MB to R phase occurs. In [110]-oriented PMN-33PT, domains are initially of mixed orthorhombic (O and MB phases, and the phase transition from O to MB phase takes place upon the external magnetic loading. Compared to PMN-28PT, the PMN-33PT single crystal exhibits much finer domain boundary structure prior to the magnetic loadings. Upon the magnetic loadings, more domain variants are induced via the phase transition in PMN-33PT than that in PMN-28PT single crystal. The finer domain band structure and more domain variants contribute to stronger piezoelectric activity. As a result, the composite of PMN-33PT/Terfenol-D manifests a stronger ME coupling than PMN-28PT/Terfenol-D composite.

  5. Structural evolution and physical properties of multiferroic Bi0.9−xLa0.1PbxFeO3−x/2 ceramics

    International Nuclear Information System (INIS)

    The polycrystalline samples of multiferroic Bi0.9−xLa0.1PbxFeO3−x/2 (x = 0–0.35) were prepared by the solid state reaction method and characterized by x-ray diffraction, field emission scanning electron microscopy, dielectric, magnetic, magnetodielectric (MD) and magnetoelectric (ME) measurements. A structural evolution from rhombohedral to pseudocubic structure was found to happen near x = 0.20. The changes and anomalies observed in magnetization were correlated with structural evolution and the development in microstructure. The ferroelectromagnetic measurements demonstrated Pb2+ doping to be a very effective method to realize the coexistence of weak ferromagnetism and ferroelectric in the ferroelectric R3c phase of BiFeO3. The MD and ME effects of Bi0.9−xLa0.1PbxFeO3−x/2 ceramics were first reported. A maximum ME voltage coefficient has been observed at x = 0.30. This work is helpful for understanding the ferroelectromagnetic behaviors and ME effect with complicated spin structures. (paper)

  6. Magneto-thermal conduction and magneto-caloric effect in poly and nano crystalline forms of multiferroic GdCrO3

    International Nuclear Information System (INIS)

    Gadolinium chromite, GdCrO3, belongs to the family of rare earth chromites, exhibiting multiferroism with coupling between electric polarization and magnetic ordering. It is understood that the interaction between Gd3+ and Cr3+ ions is responsible for switchable polarization in this system. Below Néel temperature the spins of Cr3+ ions interact in anti-parallel through super exchange mechanism, giving rise to antiferromagnetic ordering at around 169 K in poly and nanocrystalline phases of this material. In order to understand the nature of spin–lattice coupling and magnon–phonon interaction in the intermediate temperature range (150–250 K), the magneto-thermal conduction and magneto-caloric effect in poly and nanocrystalline forms of this material are reported. These properties show anomalies around 169 K, which is described as due to spin–phonon coupling. When particle sizes are reduced to nanometer scales, thermal conductivity decreases significantly while specific heat capacity increases. The former is explained as due to reduction in phonon mean free path and phonon scattering from nanoparticle interfaces, while the latter is ascribed to contributions from Einstein oscillators at weakly bound atoms at the interfaces of nanocrystals. (paper)

  7. Antiferromagnetic spin glass-like behavior in sintered multiferroic Aurivillius Bim+1Ti3Fem−3O3m+3 compounds

    International Nuclear Information System (INIS)

    The structure, hyperfine interactions and magnetic properties of the series of multiferroic Bim+1Ti3Fem−3O3m+3 Aurivillius compounds with m=4–8 were studied using X-ray diffraction, 57Fe Mössbauer spectroscopy and vibrating sample magnetometry. Samples were prepared by the conventional solid-state sintering method. Bulk magnetic measurements showed that for m=4 the compound is paramagnetic down to 2 K while in the compound with m=5 the antiferromagnetic type transition was observed at 11 K. In the case of compounds with m=6–8 much more complex magnetic behavior was found. For these compounds a gradual spin freezing and antiferromagnetic spin glass-like ordering were observed on decreasing temperature. The temperature of spin glass freezing was determined as 260, 280 and 350 K for m=6, 7 and 8, respectively. Room-temperature Mössbauer spectra of all the compounds studied confirm their paramagnetic state. However, liquid nitrogen and liquid helium temperature measurements reveal magnetic ordering with a residual paramagnetic phase contribution for the compounds with m=5–8. - Highlights: • Aurivillius compounds prepared by solid-state sintering. • Coexistence of antiferromagnetic and paramagnetic phases seen by Mössbauer spectra. • Hyperfine interactions parameters of compounds determined. • Antiferromagnetic spin glass-like ordering observed down to 10 K

  8. Multiferroic Ni0.6Zn0.4Fe2O4-BaTiO3 nanostructures: Magnetoelectric coupling, dielectric, and fluorescence

    Science.gov (United States)

    Verma, Kuldeep Chand; Singh, Sukhdeep; Tripathi, S. K.; Kotnala, R. K.

    2014-09-01

    Multiferroic nanostructures of Ni0.6Zn0.4Fe2O4-BaTiO3 (NZF/BT) have been prepared by two synthesis routes, i.e., chemical combustion (CNZF/BT) and hydrothermal (HNZF/BT). The synthesis of CNZF/BT results in nanoparticles of average size 4 nm at 500 °C annealing. However, the synthesis of HNZF/BT with hydrolysis temperature 180 °C/48 h shows nanowires of diameter 3 nm and length >150 nm. A growth mechanism in the fabrication of nanoparticles and wires is given. X-ray diffraction is used to identify the crystalline phase. The transmission electron microscopy shows the dimensions of NZF/BT nanostructures. The ferromagnetism, ferroelectricity, and magnetoelectric coupling show more enhancements in HNZF/BT nanowires than CNZF/BT nanoparticles. The observed polarization depends upon shape of nanostructures, tetragonal phase, and epitaxial strain. The tension induced by the surface curvature of nanowire counteracts the near-surface depolarizing effect and meanwhile leads to unusual enhancement of polarization. The ferromagnetism depends upon superficial spin canting, spin pinning of nanocomposite, and oxygen vacancy clusters. The magnetoelectric coefficient as the function of applied dc magnetizing field under ac magnetic field 5 Oe and frequency 1093 Hz is measured. The nanodimensions of NZF/BT are observed dielectric constant up to 120 MHz. The optical activity of NZF/BT nanostructures is shown by Fluorescence spectra.

  9. Magnetic hysteretic phenomena in multiferroic HoMnO{sub 3} single crystals and polycrystals with nano- and micrometer particle size

    Energy Technology Data Exchange (ETDEWEB)

    Galstyan, E; Lorenz, B; Yen, F; Sun, Y Y; Chu, C W [Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX 77204-5002 (United States); Martirosyan, K S [Chemical and Biomolecular Engineering Department, University of Houston, Houston, TX 77204-5002 (United States); Gospodinov, M M [Institute of Solid State Physics, Bulgarian Academy of Science, 1784 Sofia (Bulgaria)], E-mail: egalstyan@uh.edu

    2008-08-13

    We report on the magnetic properties of multiferroic hexagonal HoMnO{sub 3} single crystals and polycrystalline samples with micrometer and nanometer particle size. We have studied the in-plane and out-of-plane magnetization of HoMnO{sub 3} single crystals under low applied magnetic fields in the temperature range below T{sub Neel} = 72 K and observe the bifurcation of zero-field-cooled and field-cooled curves at the Mn spin reorientation transition temperature at 34 K. In addition, the c-axis magnetization shows a ferrimagnetic-like behavior which may relate to the magnetic Ho{sup 3+} and Mn{sup 3+} domain boundary structures and sensitively respond to changes of the magnetic structure such as spin rotations at the phase transitions near 5 and 34 K. We also studied the particles' size dependent magnetic behavior in the HoMnO{sub 3} polycrystalline samples and observe the presence of a net magnetic moment at the surface due to the large surface/volume ratio. Below the Ho{sup 3+} ordering temperature of 5 K, magnetization curves as a function of applied magnetic field, in contrast to those for the single crystal, show hysteresis behavior with coercivity, which increases with diminishing particle size.

  10. Order-disorder phase transition and multiferroic behaviour in a metal organic framework compound (CH3)2NH2Co(HCOO)3

    Science.gov (United States)

    Yadav, Ruchika; Swain, Diptikanta; Bhat, H. L.; Elizabeth, Suja

    2016-02-01

    We have investigated the multiferroic and glassy behaviour of metal-organic framework (MOF) material (CH3)2NH2Co(CHOO)3. The compound has perovskite-like architecture in which the metal-formate forms a framework. The organic cation ( CH3 ) 2 NH2 + occupies the cavities in the formate framework in the framework via N-H...O hydrogen bonds. At room temperature, the organic cation is disordered and occupies three crystallographically equivalent positions. Upon cooling, the organic cation is ordered which leads to a structural phase transition at 155 K. The structural phase transition is associated with a para-ferroelectric phase transition and is revealed by dielectric and pyroelectric measurements. Further, a PE hysteresis loop below 155 K confirms the ferroelectric behaviour of the material. Analysis of dielectric data reveal large frequency dispersion in the values of dielectric constant and tanδ which signifies the presence of glassy dielectric behaviour. The material displays a antiferromagnetic ordering below 15 K which is attributed to the super-exchange interaction between Co2+ ions mediated via formate linkers. Interestingly, another magnetic transition is also found around 11 K. The peak of the transition shifts to lower temperature with increasing frequency, suggesting glassy magnetism in the sample.

  11. Polar and Magneto-Electric Properties of Anti-Ferrodistortive Ordered Jahn-Teller Distortions in a multiferroic metal-organic framework

    International Nuclear Information System (INIS)

    There is great interest in hybrid organic-inorganic materials such as metal-organic frameworks (MOFs). Here, we focus on [C(NH2)3]Cu(HCOO)3, a MOF with perovskite topology which crystallizes in polar space group Pna21. In inorganic compounds, octahedral tilting and Jahn-Teller structural distortions are usually non-polar distortions. However, in this MOF cooperative interactions between the antiferro-distortive distortions of the framework and the C(NH2)3 organic cation via hydrogen bonding breaks the inversion symmetry and induces a ferroelectric polarization. Our ab-initio study supports the picture of an orbital-order-induced ferroelectricity, a rare example of dipolar ordering caused by electronic degrees of freedom. Moreover, we show that the switching of polarization direction implies the reversal of the weak ferromagnetic component. These results therefore offer an important starting point for tailoring multiferroic properties in this emerging class of materials for various technological applications.

  12. TbxBi1-xFeO3 nanoparticulate multiferroics fabricated by micro-emulsion technique: Structural elucidation and magnetic behavior evaluation

    KAUST Repository

    Anwar, Zobia

    2014-04-01

    Tb-doped BiFeO3 multiferroics nanoparticles fabricated via micro-emulsion route were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The fully characterized TbxBi1-xFeO3 nanoparticles were then subjected to magnetic behavior evaluation for various technological applications. The thermogravimetric analysis (TGA) conducted in the range 25-1000 C predicted the temperature (~960 C) for phase formation. XRD estimated the crystallite size 30-47 nm, while the particles size estimated by SEM was found (80-120 nm). The XRD data confirmed the rhombohedral (space group R3c) phase with average cell volume 182.66 Å3 (for BiFeO 3). Various other physical parameters like bulk density, X-ray density and porosity were also determined from the XRD data and found in agreement with theoretical predictions. The magnetic studies showed that as Bi3+ was substituted by Tb3+, all magnetic parameters were altered. The maximum saturation magnetization (Ms) (0.6691 emug -1) was exhibited by Tb0.02Bi0.98FeO 3 while the Tb0.00Bi1.00Fe1.00O 3 showed the maximum (549 Oe) coercivity. The evaluated magnetic behavior categorized these materials as soft magnetic materials that may be useful for fabricating advanced technological applications. © 2013 Elsevier B.V.

  13. Quantitative phase separation in multiferroic Bi0.88Sm0.12FeO3 ceramics via piezoresponse force microscopy

    International Nuclear Information System (INIS)

    BiFeO3 (BFO) is a classical multiferroic material with both ferroelectric and magnetic ordering at room temperature. Doping of this material with rare-earth oxides was found to be an efficient way to enhance the otherwise low piezoelectric response of unmodified BFO ceramics. In this work, we studied two types of bulk Sm-modified BFO ceramics with compositions close to the morphotropic phase boundary (MPB) prepared by different solid-state processing methods. In both samples, coexistence of polar R3c and antipolar Pbam phases was detected by conventional X-ray diffraction (XRD); the non-polar Pnma or Pbnm phase also has potential to be present due to the compositional proximity to the polar-to-non-polar phase boundary. Two approaches to separate the phases based on the piezoresponse force microscopy measurements have been proposed. The obtained fractions of the polar and non-polar/anti-polar phases were close to those determined by quantitative XRD analysis. The results thus reveal a useful method for quantitative determination of the phase composition in multi-phase ceramic systems, including the technologically most important MPB systems

  14. Spin-phonon coupling in multiferroic stoichiometric and mixed RMnO3 compounds (R=Gd, Tb, Eu:Y) studied by Raman spectroscopy

    International Nuclear Information System (INIS)

    Spin-phonon coupling, manifesting itself as phonon softening in the temperature range of the magnetically ordered phases is investigated by temperature dependent polarized Raman spectroscopy. Stoichiometric (R=Eu,Gd,Tb) and mixed (R=Eu1-xYx, 0≤x≤0.5 - covering the R ion radius range of the stoichiometric compounds) multiferroic orthorhombic RMnO3 are compared in the 10-300 K temperature range. The strength and temperature dependence of the phonon softening depend strongly on the mode symmetry showing the correlation of this effect with the magnetic interaction of the Mn3+ ions within the MnO2-plane leading to the strongest phonon renormalization for the in-plane symmetric stretching mode (B2g(1)). Quantitative spin-phonon coupling constants for all investigated systems are derived showing the trend of weakened spin-phonon coupling for decreasing R ion radius. Strikingly, spin-phonon coupling is observed even for RMnO3 compounds with an incommensurate magnetic structure of the Mn3+ spins, i.e. without long-scale magnetization. This underscores the role of phonons as a quasi-local probe.

  15. Role of defects in BiFeO₃ multiferroic films and their local electronic structure by x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ravalia, Ashish; Vagadia, Megha; Solanki, P. S.; Shah, N. A.; Kuberkar, D. G., E-mail: dgkuberkar@rediffmail.com [Department of Physics, Saurashtra University, Rajkot 360 005 (India); Gautam, S.; Chae, K. H. [Nano Material Analysis Centre, Korean Institute of Science and Technology, Seoul 136-79 (Korea, Republic of); Asokan, K. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India)

    2014-10-21

    Present study reports the role of defects in the electrical transport in BiFeO₃ (BFO) multiferroic films and its local electronic structure investigated by near-edge X-ray absorption fine structure. Defects created by high energy 200 MeV Ag⁺¹⁵ ion irradiation with a fluence of ∼5 × 10¹¹ ions/cm² results in the increase in structural strain and reduction in the mobility of charge carriers and enhancement in resistive (I-V) and polarization (P-E) switching behaviour. At higher fluence of ∼5 × 10¹² ions/cm², there is a release in the structural strain due to local annealing effect, resulting in an increase in the mobility of charge carriers, which are released from oxygen vacancies and hence suppression in resistive and polarization switching. Near-edge X-ray absorption fine structure studies at Fe L₃,₂- and O K-edges show a significant change in the spectral features suggesting the modifications in the local electronic structure responsible for changes in the intrinsic magnetic moment and electrical transport properties of BFO.

  16. Phase transformations in multiferroic Bi1−xLaxFe1−yTiyO3 ceramics probed by temperature dependent Raman scattering

    International Nuclear Information System (INIS)

    Optical phonons and phase transitions of Bi1−xLaxFe1−yTiyO3 (BLFTO, 0.02 ≤ x ≤ 0.12, 0.01 ≤ y ≤ 0.08) ceramics have been investigated by Raman scattering in the temperature range from 80 to 680 K. Four phase transitions around 140, 205, 570, and 640 K can be observed. The Raman modes are sensitive to the spin reorientation around 140 and 205 K, owing to the strong magnon-phonon coupling. The transformation around 570 K is a structural transition from rhombohedral to orthorhombic phase due to an external pressure induced by the chemical substitution. The anomalies of the phonon frequencies near Néel temperature TN have been discussed in the light of the multiferroicity. Moreover, it was found that the structural transition temperature and TN of BLFTO ceramics decrease towards room temperature with increasing doping composition as a result of size mismatch between substitution and host cations.

  17. Selective inorganic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, M.L.F.; Weisenbach, L.A.; Anderson, M.T. [Sandia National Laboratories, Albuquerque, NM (United States)] [and others

    1995-05-01

    This project is developing inorganic thin films as membranes for gas separation applications, and as discriminating coatings for liquid-phase chemical sensors. Our goal is to synthesize these coatings with tailored porosity and surface chemistry on porous substrates and on acoustic and optical sensors. Molecular sieve films offer the possibility of performing separations involving hydrogen, air, and natural gas constituents at elevated temperatures with very high separation factors. We are focusing on improving permeability and molecular sieve properties of crystalline zeolitic membranes made by hydrothermally reacting layered multicomponent sol-gel films deposited on mesoporous substrates. We also used acoustic plate mode (APM) oscillator and surface plasmon resonance (SPR) sensor elements as substrates for sol-gel films, and have both used these modified sensors to determine physical properties of the films and have determined the sensitivity and selectivity of these sensors to aqueous chemical species.

  18. Polyimide Aerogel Thin Films

    Science.gov (United States)

    Meador, Mary Ann; Guo, Haiquan

    2012-01-01

    Polyimide aerogels have been crosslinked through multifunctional amines. This invention builds on "Polyimide Aerogels With Three-Dimensional Cross-Linked Structure," and may be considered as a continuation of that invention, which results in a polyimide aerogel with a flexible, formable form. Gels formed from polyamic acid solutions, end-capped with anhydrides, and cross-linked with the multifunctional amines, are chemically imidized and dried using supercritical CO2 extraction to give aerogels having density around 0.1 to 0.3 g/cubic cm. The aerogels are 80 to 95% porous, and have high surface areas (200 to 600 sq m/g) and low thermal conductivity (as low as 14 mW/m-K at room temperature). Notably, the cross-linked polyimide aerogels have higher modulus than polymer-reinforced silica aerogels of similar density, and can be fabricated as both monoliths and thin films.

  19. Polycrystalline thin films

    Science.gov (United States)

    Zweibel, K.; Mitchell, R.; Ullal, H.

    1987-02-01

    This annual report for fiscal year 1986 summarizes the status, accomplishments, and projected future research directions of the Polycrystalline Thin Film Task in the Photovoltaic Program Branch of the Solar Energy Research Institute's Solar Electric Research Division. Subcontracted work in this area has concentrated on the development of CuInSe2 and CdTe technologies. During FY 1986, major progress was achieved by subcontractors in (1) achieving 10.5% (SERI-verified) efficiency with CdTe, (2) improving the efficiency of selenized CuInSe2 solar cells to nearly 8%, and (3) developing a transparent contact to CdTe cells for potential use in the top cells of tandem structures.

  20. Magnetic phase diagrams of hexagonal rare earth manganites, R-manganese oxide (R = holmium, erbium, thullium, ytterbium) and other multiferroics: Gadolinium triiron tetraborate, nickel orthovanadate, and holmium manganese pentoxide

    Science.gov (United States)

    Yen, Fei

    Materials exhibiting ferroelectricity or ferroelasticity and some type of magnetic order are considered to be multiferroic. The understanding of the driving mechanisms behind some of the phase transitions and the phases for which multiferroic behavior occurs is essential in order to devise applicable devices. This work studies the coexistence of various orders and how they couple with each other. The magnetic phase diagrams of hexagonal RMnO 3 (R=Ho, Er, Tm and Yb) compounds are studied and compared to each other. In the case of HoMnO3, a rich magnetic phase diagram develops at lower temperatures. For GdFe3(BO3)4, its spin rotation phase transition is found to split under the application of magnetic fields. The environment for which ferroelectricity arises is studied. For Ni3V2O8, a tri-critical point is found in its pressure-temperature phase diagram and found that with increasing pressure its magneto-electric coupling diminishes. Isotope exchange was performed on HoMn2O5 to determine its effect on any of its transition temperatures or order parameter coupling. Keywords. hexagonal RMnO3, GdFe3(BO 3)4, Ni3V2O8, HoMn 2O5, multiferroic, ferroelectricity, stacked triangular anti ferromagnet, dielectric constant, heat capacity, magneto-dielectric effect, magnetic Clausius-Clapeyron, Kagome lattice, ferroelectric polarization, pyroelectric current, isotope exchange, tri-critical point, first order phase transitions, incommensurate-commensurate phase transitions, magnetic anisotropy.

  1. Room-temperature paramagnetoelectric effect in magnetoelectric multiferroics Pb(Fe1/2Nb1/2)O3 and its solid solution with PbTiO3

    OpenAIRE

    Laguta, V. V.; Morozovska, A. N.; Eliseev, E. A.; Raevski, I. P.; Raevskaya, S. I.; Sitalo, E. I.; Prosandeev, S. A.; Bellaiche, L.

    2015-01-01

    We have observed the magnetoelectric response at room temperature and above in high-resistive ceramics made of multiferroic Pb(Fe1/2Nb1/2)O3 (PFN) and PFN-based solid solution 0.91PFN-0.09PbTiO3 (PFN-PT). The value of the paramagnetoelectric (PME) coefficient shows a pronounced maximum near the ferroelectric-to-paraelectric phase transition temperature, T_C, and then decreases sharply to zero for T>T_C. The maximal PME coefficient in PFN is about 4x10(-18) s/A. The theoretical description of ...

  2. First principles study of the multiferroics BiFeO3, Bi2FeCrO6, and BiCrO3: Structure, polarization, and magnetic ordering temperature

    OpenAIRE

    Ederer, Claude

    2005-01-01

    PUBLISHED We present results of an ab initio density-functional theory study of three bismuth-based multiferroics, BiFeO3, Bi2FeCrO6, and BiCrO3. We disuss differences in the crystal and electronic structure of the three systems and show that the application of the LDA+U method is essential to obtain realistic structural parameters for Bi2FeCrO6. We calculate the magnetic nearest-neighbor coupling constants for all three systems and show how Anderson's theory of superexchange can be applie...

  3. Multiferroic properties of nanocrystalline BiFe{sub 1−x}Ni{sub x}O{sub 3} (x=0.0–0.15) perovskite ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhari, Yogesh [Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon 425001, Maharastra (India); Department of Physics, Shri. Pancham Khemaraj Mahavidyalaya, Sawantwadi 416510, Maharastra (India); Mahajan, Chandrashekhar M. [Department of Engineering Sciences and Humanities (DESH), Vishwakarma Institute of Technology, Pune 411 016, Maharastra (India); Singh, Amrita [Magnetics and Advanced Ceramics Laboratory, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Jagtap, Prashant [Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon 425001, Maharastra (India); Chatterjee, Ratnamala [Magnetics and Advanced Ceramics Laboratory, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Bendre, Subhash, E-mail: bendrest@gmail.com [Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon 425001, Maharastra (India)

    2015-12-01

    Ni doped BiFeO{sub 3} (x=0, 0.05, 0.1 and 0.15) nanocrystalline ceramics were synthesized by the solution combustion method (SCM) to obtain optimal multiferroic properties. The effect of Ni doping on structural, morphological, ferroelectric, magnetic and dielectric properties of BiFeO{sub 3} was studied. The structural investigations by using X-ray diffraction (XRD) pattern confirmed that BiFe{sub 1−x}Ni{sub x}O{sub 3} ceramics have rhombhohedral perovskite structure. The ferroelectric hysteresis measurements for BiFe{sub 1−x}Ni{sub x}O{sub 3} (x=0, 0.05, 0.1, 0.15) compound at room temperature found to exhibit unsaturated behavior and presents partial reversal of polarization. The magnetic measurements demonstrated an enhancement of ferromagnetic property due to Ni doping in BiFeO{sub 3} when compared with undoped BiFeO{sub 3}. The variation of dielectric constant with temperature in BiFe{sub 0.9}Ni{sub 0.1}O{sub 3} and BiFe{sub 0.85}Ni{sub 0.15}O{sub 3} samples evidenced an apparent dielectric anomaly around 350 °C and 300 °C which corresponds to antiferromagnetic to paramagnetic phase transition of (T{sub N}) of BiFeO{sub 3}. The dependence of room temperature dielectric properties on frequency signifies that both dielectric constant (ε) and dielectric loss (tan δ) are the strong function of frequency. The results show that solution combustion method leads to synthesis of an excellent and reproducible BiFe{sub 1−x}Ni{sub x}O{sub 3} multiferroic ceramics. - Highlights: • Synthesis of BiFe{sub 1−x}Ni{sub x}O{sub 3} (x=0, 0.05, 0.1 and 0.15) multiferroic ceramics. • Solution Combustion Method (SCM). • Ferroelectric and dielectric properties of undoped and Ni doped BiFeO{sub 3} ceramics. • High temperature synthesis of BiFe{sub 1−x}Ni{sub x}O{sub 3} multiferroic ceramics. • First detailed report about SCM synthesized the BiFe{sub 1−x}Ni{sub x}O{sub 3} ceramics.

  4. Effects of electric-field-induced piezoelectric strain on the electronic transport properties of La{sub 0.9}Ce{sub 0.1}MnO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, R.K., E-mail: zrk@ustc.edu [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Department of Applied Physics and Materials Research Center, The Hong Kong Polytechnic University, Hong Kong (China); Dong, S.N. [Department of Physics and Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026 (China); Wu, Y.Q.; Zhu, Q.X. [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Wang, Y.; Chan, H.L.W. [Department of Applied Physics and Materials Research Center, The Hong Kong Polytechnic University, Hong Kong (China); Li, X.M.; Luo, H.S. [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Li, X.G. [Department of Physics and Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026 (China)

    2012-12-15

    The authors constructed multiferroic structures by growing La{sub 0.9}Ce{sub 0.1}MnO{sub 3} (LCEMO) thin films on piezoelectric 0.68Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.32PbTiO{sub 3} (PMN-PT) single-crystal substrates. Due to the efficient elastic coupling at the interface, the electric-field-induced piezoelectric strain in PMN-PT substrates is effectively transferred to LCEMO films and thus, leads to a decrease in the resistance and an increase in the magnetoresistance of the films. Particularly, it was found that the resistance-strain coefficient [({Delta}R/R){sub film}/({Delta}{epsilon}{sub zz}){sub film}] of the LCEMO film was considerably enhanced by the application of magnetic fields, demonstrating strong coupling between the lattice and the spin degrees of freedom. ({Delta}R/R){sub film}/({Delta}{epsilon}{sub zz}){sub film} at 122 K was enhanced by {approx} 28.8% by a magnetic field of 1.2 T. An analysis of the overall results demonstrates that the phase separation is crucial to understand strain-mediated modulation of electronic transport properties of manganite film/PMN-PT multiferroic structures. - Highlights: Black-Right-Pointing-Pointer La{sub 0.9}Ce{sub 0.1}Mn{sub O3} films were epitaxially grown on piezoelectric single crystals. Black-Right-Pointing-Pointer Piezoelectric strain influences the electronic transport properties of films. Black-Right-Pointing-Pointer Magnetic field enhances the piezoelectric strain effect. Black-Right-Pointing-Pointer Phase separation is crucial to understand the piezoelectric strain effect.

  5. Learning unit: Thin lenses

    Science.gov (United States)

    Nita, L.-S.

    2012-04-01

    Learning unit: Thin lenses "Why objects seen through lenses are sometimes upright and sometimes reversed" Nita Laura Simona National College of Arts and Crafts "Constantin Brancusi", Craiova, Romania 1. GEOMETRIC OPTICS. 13 hours Introduction (models, axioms, principles, conventions) 1. Thin lenses (Types of lenses. Defining elements. Path of light rays through lenses. Image formation. Required physical quantities. Lens formulas). 2. Lens systems (Non-collated lenses. Focalless systems). 3. Human eye (Functioning as an optical system. Sight defects and their corrections). 4. Optical instruments (Characteristics exemplified by a magnifying glass. Paths of light rays through a simplified photo camera. Path of light rays through a classical microscope) (Physics curriculum for the IXth grade/ 2011). This scenario exposes a learning unit based on experimental sequences (defining specific competencies), as a succession of lessons started by noticing a problem whose solution assumes the setup of an experiment under laboratory conditions. Progressive learning of theme objectives are realised with sequential experimental steps. The central cognitive process is the induction or the generalization (development of new knowledge based on observation of examples or counterexamples of the concept to be learnt). Pupil interest in theme objectives is triggered by problem-situations, for example: "In order to better see small objects I need a magnifying glass. But when using a magnifier, small object images are sometimes seen upright and sometimes seen reversed!" Along the way, pupils' reasoning will converge to the idea: "The image of an object through a lens depends on the relative distances among object, lens, and observer". Associated learning model: EXPERIMENT Specific competencies: derived from the experiment model, in agreement with the following learning unit steps I. Evoking - Anticipation: Size of the problem, formulation of hypotheses and planning of experiment. II

  6. Interfaces and thin films physics

    International Nuclear Information System (INIS)

    The 1988 progress report of the Interfaces and Thin Film Physics laboratory (Polytechnic School France) is presented. The research program is focused on the thin films and on the interfaces of the amorphous semiconductor materials: silicon and silicon germanium, silicon-carbon and silicon-nitrogen alloys. In particular, the following topics are discussed: the basic processes and the kinetics of the reactive gas deposition, the amorphous materials manufacturing, the physico-chemical characterization of thin films and interfaces and the electron transport in amorphous semiconductors. The construction and optimization of experimental devices, as well as the activities concerning instrumentation, are also described

  7. Comparative studies of ferroelectric and magnetic phase transitions in Pb(Fe.sub.1/2./sub.Nb.sub.1/2./sub.)O.sub.3./sub.-PbMO.sub.3./sub. (M-Ti, Zr) multiferroic solid solutions

    Czech Academy of Sciences Publication Activity Database

    Raevski, I. P.; Titov, V.V.; Laguta, Valentyn; Maryško, Miroslav; Kubrin, S.P.; Chen, H.; Chou, C.-C.; Blazhevich, A.V.; Raevskaya, S. I.; Sarychev, D.A.; Minasyan, T.A.; Pustovaya, L.A.; Zakharchenko, I. N.; Malitskaya, M. A.

    2015-01-01

    Roč. 475, č. 1 (2015), s. 20-30. ISSN 0015-0193 R&D Projects: GA ČR GA13-11473S Institutional support: RVO:68378271 Keywords : ferroelectrics * multiferroics * phase transition Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.469, year: 2014

  8. Highly Oscillating Thin Obstacles

    CERN Document Server

    Lee, Ki-ahm; Yoo, Minha

    2012-01-01

    The focus of this paper is on a thin obstacle problem where the obstacle is defined on the intersection between a hyper-plane $\\Gamma$ in $\\mathbb{R}^n$ and a periodic perforation $\\mathcal{T}_\\varepsilon$ of $\\mathbb{R}^n$, depending on a small parameter $\\varepsilon>0$. As $\\varepsilon\\to 0$, it is crucial to estimate the frequency of intersections and to determine this number locally. This is done using strong tools from uniform distribution. By employing classical estimates for the discrepancy of sequences of type $\\{k\\alpha\\}_{k=1}^\\infty$, $\\alpha\\in\\R$, we are able to extract rather precise information about the set $\\Gamma\\cap\\mathcal{T}_\\varepsilon$. As $\\varepsilon\\to0$, we determine the limit $u$ of the solution $u_\\varepsilon$ to the obstacle problem in the perforated domain, in terms of a limit equation it solves. We obtain the typical "strange term" behaviour for the limit problem, but with a different constant taking into account the contribution of all different intersections, that we call the...

  9. Thin, Flexible IMM Solar Array

    Science.gov (United States)

    Walmsley, Nicholas

    2015-01-01

    NASA needs solar arrays that are thin, flexible, and highly efficient; package compactly for launch; and deploy into large, structurally stable high-power generators. Inverted metamorphic multijunction (IMM) solar cells can enable these arrays, but integration of this thin crystalline cell technology presents certain challenges. The Thin Hybrid Interconnected Solar Array (THINS) technology allows robust and reliable integration of IMM cells into a flexible blanket comprising standardized modules engineered for easy production. The modules support the IMM cell by using multifunctional materials for structural stability, shielding, coefficient of thermal expansion (CTE) stress relief, and integrated thermal and electrical functions. The design approach includes total encapsulation, which benefits high voltage as well as electrostatic performance.

  10. Ultimately Thin Metasurface Wave Plates

    OpenAIRE

    Keene, David; LePain, Matthew; Durach, Maxim

    2015-01-01

    Optical properties of a metasurface which can be considered a monolayer of two classical uniaxial metamaterials, parallel-plate and nanorod arrays, are investigated. It is shown that such metasurface acts as an ultimately thin sub-50 nm wave plate. This is achieved via an interplay of epsilon-near-zero and epsilon-near-pole behavior along different axes in the plane of the metasurface allowing for extremely rapid phase difference accumulation in very thin metasurface layers. These effects are...

  11. Thin-film solar cell

    NARCIS (Netherlands)

    Metselaar, J.W.; Kuznetsov, V.I.

    1998-01-01

    The invention relates to a thin-film solar cell provided with at least one p-i-n junction comprising at least one p-i junction which is at an angle alpha with that surface of the thin-film solar cell which collects light during operation and at least one i-n junction which is at an angle beta with t

  12. Rotating Thin-Shell Wormhole

    OpenAIRE

    Ovgun, A.

    2016-01-01

    In this article, we construct rotating thin shell wormhole using a Myers-Perry black hole in five dimensions. The stability of the wormhole is analyzed under perturbations follows from the Darmois-Israel junction conditions. We find that it required exotic matter at the throat to keep throat of wormhole stable. Our analysis shows that the stability of the rotating thin-shell wormhole is available with choosing suitable values of parameters.

  13. Bi deficiency-tuned functionality in multiferroic Bi1-δFe0.95Mn0.05O3 films

    Science.gov (United States)

    Chen, Jingyi; Wang, Yao; Wang, Hui; Zhang, Shuangmei; Deng, Yuan

    2016-01-01

    Structural evolution and ferroelectric (FE)-to-antiferroelectric (AFE) transition behaviors were observed in Bi1-δFe0.95Mn0.05O3 (100)-textured films with a carefully controlled Bi deficiency concentration δ. Raman spectra revealed an orthorhombic structural transition induced by Mn substitution. The polarization-electric field hysteresis loops and capacitance-voltage loops of Bi1-δFe0.95Mn0.05O3 films clearly demonstrated antiferroelectric behavior with increasing δ. The responses of the domain structure of the Bi1-δFe0.95Mn0.05O3 film under positive and negative applied voltages directly suggested the coexistence of FE and AFE phases. The existence of (100) superstructure reflections and antiparallel displacements of the Bi atoms along the [100] direction observed by transmission electron microscopy unambiguously reveal the AFE phase. The chemical substitution-induced orthorhombic structural transition in BiFe0.95Mn0.05O3 film implies that as the δ concentration increases, the changes in Bi-O bonding and the stereochemical activity of Bi 6s lone pair affect both the ferroelectric distortion and the antiferrodistortive rotation and therefore drive the Bi1-δFe0.95Mn0.05O3 crystal lattice to form a PbZrO3-type orthorhombic phase with an AFE order. A continuing increase in Bi deficiency creates defect dipole complexes which produce an internal field leading to a preferred direction of the ferroelectric domain. The Bi deficiency in multiferroic BiFeO3 provides a new route by which to tune functionality.

  14. Structural defects as a factor controlling the magnetic properties of pure and Ti-doped Bi(1-x)Ca(x)FeO(3-x/2) multiferroics.

    Science.gov (United States)

    Khomchenko, V A; Paixão, J A

    2015-11-01

    Recognition of the factors that may significantly affect the multiferroic properties of BiFeO3-based perovskites remains one of the most challenging tasks in condensed matter physics. To reveal the reasons behind the doping-driven instability of the cycloidal antiferromagnetic order in the polar phase of Bi(1-x)Ca(x)FeO(3-x/2), synthesis and investigation of the crystal structure, microstructure, local ferroelectric and magnetic properties of the ceramic samples of Bi0.9Ca0.1Fe(1-x)Ti(x)O(3-δ) (x  =  0.05, 0.1, 0.15) have been carried out. The compounds possess a rhombohedral structure (space group R3c). The compositional dependence of unit cell volume in this series can be interpreted as suggesting the doping-induced elimination of anion vacancies at x  ⩽  0.1 and the formation of cation vacancies at x  >  0.1. The filling of oxygen vacancies suppresses a weak ferromagnetic contribution characteristic of the parent Bi0.9Ca0.1FeO2.95. The appearance of cation vacancies restores the weak ferromagnetic phase. The key role of lattice defects in the magnetic behavior of Ca-doped BiFeO3 has been confirmed by the observation of a correlation between the magnetic properties and the morphology/ferroelectric domain structure of the Bi0.9Ca0.1Fe(1-x)Ti(x)O(3-δ) ceramics. PMID:26447603

  15. Self-assembly of multiferroic core-shell particulate nanocomposites through DNA-DNA hybridization and magnetic field directed assembly of superstructures

    Science.gov (United States)

    Sreenivasulu, Gollapudi; Lochbiler, Thomas A.; Panda, Manashi; Srinivasan, Gopalan; Chavez, Ferman A.

    2016-04-01

    Multiferroic composites of ferromagnetic and ferroelectric phases are of importance for studies on mechanical strain mediated coupling between the magnetic and electric subsystems. This work is on DNA-assisted self-assembly of superstructures of such composites with nanometer periodicity. The synthesis involved oligomeric DNA-functionalized ferroelectric and ferromagnetic nanoparticles, 600 nm BaTiO3 (BTO) and 200 nm NiFe2O4 (NFO), respectively. Mixing BTO and NFO particles, possessing complementary DNA sequences, resulted in the formation of ordered core-shell heteronanocomposites held together by DNA hybridization. The composites were imaged by scanning electron microscopy and scanning microwave microscopy. The presence of heteroassemblies along with core-shell architecture is clearly observed. The reversible nature of the DNA hybridization allows for restructuring the composites into mm-long linear chains and 2D-arrays in the presence of a static magnetic field and ring-like structures in a rotating-magnetic field. Strong magneto-electric (ME) coupling in as-assembled composites is evident from static magnetic field H induced polarization and low-frequency magnetoelectric voltage coefficient measurements. Upon annealing the nanocomposites at high temperatures, evidence for the formation of bulk composites with excellent cross-coupling between the electric and magnetic subsystems is obtained by H-induced polarization and low-frequency ME voltage coefficient. The ME coupling strength in the self-assembled composites is measured to be much stronger than in bulk composites with randomly distributed NFO and BTO prepared by direct mixing and sintering.

  16. Effect of Al3+ substitution on the structural, magnetic, and electric properties in multiferroic Bi2Fe4O9 ceramics

    International Nuclear Information System (INIS)

    Structural, magnetic, and electric properties have been investigated in polycrystalline Bi2(Fe1−xAlx)4O9 (0≤x≤0.25) ceramics synthesized by a modified Pechini method. Structural analysis reveals that Al3+ doped Bi2Fe4O9 crystallizes in orthorhombic structure with Pbnm space group. Surface morphology of the end products is examined by scanning electron microscopy and the grain size has a tendency to decrease with increase in Al3+ doping level. Compared with pure Bi2Fe4O9, room temperature coexistent multiferroic-like behavior is observed in Al3+ doped Bi2Fe4O9. By analyzing magnetic properties, the Néel temperature monotonously shifts to low temperatures from ~260 K (x=0) to ~35 K (x=0.25). Moreover, the spin dynamic measured by the shift in ac magnetic susceptibility as a function of frequency provides a possibility of spin-glass-like behavior, which is further confirmed by fitting the critical slowing down power law and memory effect. - Graphical abstract: Compared with pure Bi2Fe4O9, room temperature weak ferromagnetic property and enhanced ferroelectric-like behavior can be achieved simultaneously with proper Al3+ doping. - Highlights: • Bi2(Fe1−xAlx)4O9 (0≤x≤0.25) ceramics are fabricated via a Pechini method. • Weak ferromagnetic and ferroelectric behaviors can be achieved simultaneously. • Spin-glass-like behavior is detected with proper Al3+ doping. • The memory and aging effects are observed with proper Al3+ doping

  17. Structural, spectroscopic, and dielectric characterizations of Mn-doped 0.67BiFeO3-0.33BaTiO3 multiferroic ceramics

    KAUST Repository

    Hang, Qiming

    2013-09-07

    0.67BiFeO3-0.33BaTiO3 multiferroic ceramics doped with x mol% MnO2 (x = 2–10) were synthesized by solid-state reaction. The formation of a perovskite phase with rhombohedral symmetry was confirmed by X-ray diffraction (XRD). The average grain sizes were reduced from 0.80 μm to 0.50 μm as increasing the Mn-doped levels. Single crystalline nature of the grains was revealed by high-resolution transmission electron microscopy (HRTEM) images and electron diffraction patterns. Polar nano-sized ferroelectric domains with an average size of 9 nm randomly distributed in the ceramic samples were revealed by TEM images. Ferroelectric domain lamellae (71° ferroelectric domains) with an average width of 5 nm were also observed. Vibrational modes were examined by Raman spectra, where only four Raman peaks at 272 cm−1 (E-4 mode), 496 cm−1 (A 1-4 mode), 639 cm−1, and 1338 cm−1 were observed. The blue shifts in the E-4 and A 1-4 Raman mode frequencies were interpreted by a spring oscillator model. The dieletric constants of the present ceramics as a function of the Mn-doped levels exhibited a V-typed curve. They were in the range of 350–700 measured at 103 Hz, and the corresponding dielectric losses were in range of 0.43–0.96, approaching to 0.09 at 106 Hz.

  18. The structural and multiferroic properties of (Bi{sub 1-x}La{sub x})(Fe{sub 0.95}Co{sub 0.05})O{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Xu Qingyu, E-mail: xuqingyu@seu.edu.cn [Department of Physics, Southeast University, Nanjing, Jiangsu 211189 (China); Key Laboratory of MEMS of the Ministry of Education, Southeast University, Nanjing 210096 (China); Zheng Xiaohong [Department of Physics, Southeast University, Nanjing, Jiangsu 211189 (China); Wang Liaoyu [Department of Physics, Nanjing University, Nanjing 210008 (China); Zhang Yan [Department of Physics, Southeast University, Nanjing, Jiangsu 211189 (China); Wang Dunhui [Department of Physics, Nanjing University, Nanjing 210008 (China); Xu Mingxiang [Department of Physics, Southeast University, Nanjing, Jiangsu 211189 (China)

    2012-12-15

    La and Co co-doped BiFeO{sub 3} ((Bi{sub 1-x}La{sub x})(Fe{sub 0.95}Co{sub 0.05})O{sub 3} (x=0, 0.10, 0.20, 0.30)) ceramics were prepared by tartaric acid modified sol-gel method. The X-ray diffraction patterns indicate a transition from rhombohedral structure to tetragonal structure at x=0.20, which has been confirmed by the Raman measurements. The band gap increases with increasing x to 0.20, and then decreases with further increasing x to 0.30. The structural transition has significant effects on the multiferroic properties. The remnant magnetization and saturate ferromagnetic magnetization decrease abruptly with increasing x to 0.10, and then gradually increase with further increasing x up to 0.30. The coercivity is significantly reduced with increasing La doping concentration. The ferroelectricity has been improved by La doping, and the polarization increases with increasing x to 0.10, then decreases with further increasing x up to 0.30. The simultaneous coexistence of soft ferromagnetism and ferroelectricity at room temperature in tetragonal Bi{sub 0.70}La{sub 0.30}Fe{sub 0.95}Co{sub 0.05}O{sub 3} indicates the potential multiferroic applications.

  19. Analysis of azimuthal-angle scans in resonant X-ray Bragg diffraction and parity even and odd atomic multipoles in the multiferroic modification of the terbium manganate, TbMnO3

    International Nuclear Information System (INIS)

    We present a theoretical analysis of resonant x-ray Bragg diffraction data from multiferroic TbMnO3 presented by Mannix et al PRB76, 184420 and Voigt et al. PRB 76, 104431. We have chosen an approach that does not rely on knowledge of the low-temperature phase space group of the sample, which is not precisely known. Results show that the low-temperature satellite reflections originate from dipole-dipole (E1-E1) and dipole-quadrupole (E1-E2) events. Presence on quadrupole-quadrupole (E2-E2) events can be excluded. The physical origin of the data is discussed in terms of atomic multipoles that represent magnetization, lattice distortions, and magneto-electric properties of the Tb and Mn ions. A handed cycloid of atomic multipoles, traced out in the b-c plane, is shown to be a plausible model of the Tb electron structure within a multiferroic modification that exists in the temperature interval 7 K < T < 28 K. (author)

  20. Predictive study of structural, electronic, magnetic and thermodynamic properties of XFeO3 (X = Ag, Zr and Ru multiferroic materials in cubic perovskite structure: first-principles calculations

    Directory of Open Access Journals (Sweden)

    Moulay N.

    2015-06-01

    Full Text Available The full potential linear-muffin-tin-orbital method within the spin local density approximation has been used to study the structural, electronic, magnetic and thermodynamic properties of three multiferroic compounds of XFeO3 type. Large values of bulk modulus for these compounds have been obtained, which demonstrates their hardness. The calculated total and partial density of states of these compounds shows a complex of strong hybridized 3d and 4d states at Fermi level. The two degenerate levels eg and t2g clearly demonstrate the origin of this complex. We have also investigated the effect of pressure, from 0 GPa to 55 GPa, on the magnetic moment per atom and the exchange of magnetic energy between the ferromagnetic and antiferromagnetic states. For more detailed knowledge, we have calculated the thermodynamic properties, and determined heat capacity, Debye temperature, bulk modulus and enthropy at different temperatures and pressures for the three multiferroic compounds. This is the first predictive calculation of all these properties.

  1. Diffused phase transitions in Pb(Zr{sub 0.65}Ti{sub 0.35})O{sub 3}-Pb(Fe{sub 2/3}W{sub 1/3})O{sub 3} multiferroics

    Energy Technology Data Exchange (ETDEWEB)

    Tirupathi, Patri [Department of Physics, Rajiv Gandhi University of Knowledge Technologies, R K Valley 516329 (India); Kumar, Nawnit [Department of Physics, Indian Institute of Technology, Kharagpur 721302 (India); Pastor, Mukul, E-mail: mukul.ptr@gmail.com; Pandey, A. C. [Department of Physics, Bundelkhand University, Jhansi (U.P.) 284002 (India); Choudhary, R. N. P. [Department of Physics, Institute of Technical Education and Research, Siksha O Anusandhan University, Bhubaneswar 751030, Odisha (India)

    2015-02-21

    The solid solutions of (1−x)Pb(Zr{sub 0.65}Ti{sub 0.35})O{sub 3}-xPb(Fe{sub 2/3}W{sub 1/3})O{sub 3} in different ratios were fabricated by a high-temperature solid-state reaction method using high-purity oxides for possible multi-ferroic applications. Structural analysis using x-ray diffraction powder patterns of the system by Rietveld refinement method exhibits the formation of rhombohedral phase with R3c space group. Detailed studies of dielectric permittivity as a function of temperature of the systems show that the frequency independent dielectric maximum temperature shifts toward room temperature on increasing x. In addition to this, the degree of diffuseness of the permittivity anomaly is more pronounced for higher content of Pb(Fe{sub 2/3}W{sub 1/3})O{sub 3}, implying the existence of a composition-induced diffuse phase transition for the limited range of compositional ratios. Detailed impedance spectroscopy analysis shows the contributions of grain, grain boundary, and interfacial polarizations in the resistive characteristics and conduction mechanism of the materials. The weak ferromagnetic and saturated ferroelectric loops indicate that system with x = 0.1, 0.2 have good multiferroic characteristics, and may be useful for future spintronic devices.

  2. Two phase multiferroics for voltage-induced entropy change with application in near-room-temperature refrigeration

    Science.gov (United States)

    Giri, Prakash; Kumar, Dhananjay; Binek, Christian

    The demand for environmental friendly, cost-effective and energy efficient cooling drives the emerging technology of magnetic refrigeration at room temperature. We fabricate a two phase mutiferroic La0.7Sr0.3MnO3/Pb(Mg1/3Nb2/3) O3-PbTiO3(001) via pulsed laser deposition for application in advanced near room-temperature refrigeration and miniature cooling devices. The key innovation rests on utilizing the magnetocaloric effect in zero applied magnetic fields. The magnetocaloric effect of the composite is activated purely by electric field. We utilize strain originating from stress which is voltage-induced via the inverse piezoelectric effect of PMN-PT. The strain is carried over into the adjacent LSMO thin film thus changing its magnetic order. The voltage-induced variation in magnetization leads to change in isothermal entropy when the experiment is carried out in contact with a thermostat and gives correspondingly rise to an adiabatic temperature change when heat exchange is suppressed. This project is supported by NSF through Nebraska MRSEC DMR-1420645.

  3. Proximate transition temperatures amplify linear magnetoelectric coupling in strain-disordered multiferroic BiMnO3

    Science.gov (United States)

    Mickel, Patrick R.; Jeen, Hyoungjeen; Kumar, Pradeep; Biswas, Amlan; Hebard, Arthur F.

    2016-04-01

    We report a giant linear magnetoelectric coupling in strained BiMnO3 thin films in which the disorder associated with an islanded morphology gives rise to extrinsic relaxor ferroelectricity that is not present in bulk centrosymmetric ferromagnetic crystalline BiMnO3. Strain associated with the disorder is treated as a local variable, which couples to the two ferroic order parameters, magnetization M ⃗ and polarization P ⃗. A straightforward "gas under a piston" thermodynamic treatment explains the observed correlated temperature dependencies of the product of susceptibilities and the magnetoelectric coefficient together with the enhancement of the coupling by the proximity of the ferroic transition temperatures close to the relaxor freezing temperature. Our interpretation is based on a trilinear coupling term in the free energy of the form L ⃗.(P ⃗×M ⃗) , where L ⃗ is a hidden antiferromagnetic order parameter, previously postulated by theory for BiMnO3. This phenomenological invariant not only preserves inversion and time-reversal symmetry of the strain-induced interactions but also explains the pronounced linear magnetoelectric coupling without using the more conventional higher order biquadratic interaction proportional to (P⃗.M ⃗) 2.

  4. The endometrium in assisted reproductive technology: How thin is thin?

    Directory of Open Access Journals (Sweden)

    Nalini Mahajan

    2016-01-01

    Full Text Available A thin endometrium is encountered infrequently (2.4% in assisted reproductive technology cycles. When it does occur it is a cause of concern as it is associated with lower implantation rate and pregnancy rate. Though pregnancies have been reported at 4 and 5 mm it is apparent that an endometrial thickness <6 mm is associated with a trend toward lower probability of pregnancy. Hormone replacement therapy – frozen embryo transfer (FET cycles appear to give better results due to an improvement in endometrial receptivity (ER. The etiology of thin endometrium plays a significant part in its receptivity. A number of treatments have been tried to improve endometrial growth, but none has been validated so far. Confirming ER of a thin endometrium by an ER array test before FET offers reassurance.

  5. Direct Observation of Magnetic Field Induced Ferroelectric Domain Evolution in Self-Assembled Quasi (0-3) BiFeO3-CoFe2O4 Thin Films.

    Science.gov (United States)

    Li, Linglong; Lu, Lu; Zhang, Dawei; Su, Ran; Yang, Guang; Zhai, Junyi; Yang, Yaodong

    2016-01-13

    Strain-mediated magnetoelectric (ME) coupling effect is expected in self-assembly heterostructures engineered by ferroelectric and ferromagnetic materials, contributing to the enhanced overall magnetoelectric effect. Microstructures as well as the connectivity configuration are considered to play a significant role in achieving efficient magnetoelectric properties. Different from the conventional (1-3) and (2-2) type composite films, we fabricate BiFeO3-CoFe2O4 (BFO-CFO) composite thin films with a novel quasi (0-3) type connectivity via a dual-target pulsed laser deposition process. The self-assembly growth mechanism has been studied, which demonstrates that the perovskite (BFO) matrix segments the connectivity of spinel (CFO) resulting in a quasi (0-3) composite. Direct observation of ferroelectric domain wall motion under external magnetic fields proves a strong magnetoelectric coupling effect in these (0-3) thin films. Our preliminary findings reveal the promising application potential of this new structure as multiferroic domain wall devices. PMID:26698906

  6. Obese people's perceptions of the thin ideal.

    Science.gov (United States)

    Couch, Danielle; Thomas, Samantha L; Lewis, Sophie; Blood, R Warwick; Holland, Kate; Komesaroff, Paul

    2016-01-01

    The media play a key role in promoting the thin ideal. A qualitative study, in which we used in depth interviews and thematic analysis, was undertaken to explore the attitudes of 142 obese individuals toward media portrayals of the thin ideal. Participants discussed the thin ideal as a social norm that is also supported through the exclusion of positive media portrayals of obese people. They perceived the thin ideal as an 'unhealthy' mode of social control, reflecting on their personal experiences and their concerns for others. Participants' perceptions highlighted the intersections between the thin ideal and gender, grooming and consumerism. Participants' personal responses to the thin ideal were nuanced--some were in support of the thin ideal and some were able to critically reflect and reject the thin ideal. We consider how the thin ideal may act as a form of synoptical social control, working in tandem with wider public health panoptical surveillance of body weight. PMID:26685706

  7. Strain effect on the magnetic properties of SrRuO{sub 3} thin films on ferroelectric PMN-PT substrates

    Energy Technology Data Exchange (ETDEWEB)

    Herklotz, Andreas; Kataja, Mikko; Schultz, Ludwig; Doerr, Kathrin [IFW Dresden, IMW, Helmholtzstrasse 20, 01069 Dresden (Germany)

    2011-07-01

    We investigate a two-component multiferroic system consisting of a ferroelectric 0.72PbMg{sub 1/3}Nb{sub 2/3}O{sub 3}-0.28PbTiO{sub 3} (PMN-PT) substrate and ferromagnetic SrRuO{sub 3} (SRO) thin films. The inverse piezoelectric effect of the substrate is used to reversibly vary the strain state of the epitaxial SRO films in order to clarify the strain dependence of the magnetic film properties. Buffer films of Sr{sub 1-x}Ba{sub x}TiO{sub 3} are introduced to vary the as-grown state of the SRO films and to cover a wider range from compressive to tensile strain. High resolution X-ray diffraction is deployed to structurally characterize the films and to determine Poisson's ratio of SRO, which is not known so far. SQUID magnetometry reveals that the Curie temperature is increasing with tensile strain, but starts to decrease again under high strain. Angular-dependent measurements provide that the easy axis orientation shows a complex dependence on strain and temperature. SQUID measurements on conventional substrates like SrTiO{sub 3} and LaAlO{sub 3} and electric transport measurements complete the data.

  8. Photovoltaic properties of Aurivillius phase Bi{sub 5}FeTi{sub 3}O{sub 15} thin films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kooriyattil, Sudheendran [Department of Physics and Institute for Functional Nanomaterials, University of Puerto Rico, P.O. Box 70377, San Juan, Puerto Rico 00936-8377 (United States); Department of Physics, Sree Kerala Varma College, Thrissur 680011, Kerala (India); Katiyar, Rajesh K.; Pavunny, Shojan P., E-mail: rkatiyar@uprrp.edu, E-mail: shojanpp@gmail.com; Morell, Gerardo; Katiyar, Ram S., E-mail: rkatiyar@uprrp.edu, E-mail: shojanpp@gmail.com [Department of Physics and Institute for Functional Nanomaterials, University of Puerto Rico, P.O. Box 70377, San Juan, Puerto Rico 00936-8377 (United States)

    2014-08-18

    We report a remarkable photovoltaic effect in pulsed laser deposited multiferroic aurivillius phase Bi{sub 5}FeTi{sub 3}O{sub 15} (BFTO) thin films sandwiched between ZnO:Al transparent conductive oxide top electrode and SrRuO{sub 3} bottom electrode fabricated on amorphous fused silica substrates. The structural and micro structural properties of these films were analysed by X-ray diffraction and atomic force microscopy techniques. The films were showing a photo sensitive ferroelectric behaviour with a notable apparent polarization in the range of 10–15 μC/cm{sup 2}. These films also exhibited a switchable photo-response and this parameter was observed to be sensitive to polarisation field and the polarization direction. The device shows a large ON/OFF photo current ratio with an open circuit voltage of 0.14 V. The photo response at zero bias of this BFTO based heterostructures showed rapid increase to a saturation value of 6 μA at zero bias.

  9. [Obesity and thinness in painting].

    Science.gov (United States)

    Schüller Pérez, Amador

    2004-01-01

    The obesity, serious frequenty sanitary problem, cause of complications that effects to the expectation of life, with aesthetic repercussion and with an increase in the last decades. Admitted the obesity android, gynoide, central or abdominal, wide aesthetic repercussion and physiopathologic like hyperdislipemias, metabolic alterations (diabetes mellitus, etc...), arterial hypertension, column arthrosis and outlying. Ethiopathologics co-factors, sedentariness, genotypic predisposition, endocrine alterations and of the leptina secretion. Illustrative cases of obesity in the painting of those that characteristic models are exposed, from slight grades to intense affecting to both genders. The thinness counterpoint of the obesity, multicausal process, less frequent than the obesity with aesthetic and psychological repercussion. It is the formed aesthetic thinness to the diverse types physiopathologic, without forgetting the constitutional and family form and the anorexy, the serial ones to disasters, wars, famines, etc..., the mystic thinness of saints and ascetics, and the serial one to consuming processes. PMID:15997591

  10. Biogas production from thin stillage

    OpenAIRE

    Moestedt, Jan

    2015-01-01

    The biogas plant in Norrköping (Tekniska verken i Linköping AB, publ.), Sweden, operates with thin stillage, a residue from bio-ethanol fermentation, as the main feedstock. Thin stillage is energy-rich due to its high protein content, but due to its high nitrogen and sulphate content is a somewhat complicated feedstock. The high nitrogen concentration results in inhibition of the microbial process and also selects for nitrogen-tolerant, but slow-growing, syntrophic acetate-oxidising bacteria ...

  11. Thin-film ternary superconductors

    International Nuclear Information System (INIS)

    Physical properties and preparation methods of thin film ternary superconductors, (mainly molybdenum chalcogenides) are reviewed. Properties discussed include the superconducting critical fields and critical currents, resistivity and the Hall effect. Experimental results at low temperatures, together with electron microscopy data are used to determine magnetic flux pinning mechanisms in films. Flux pinning results, together with an empirical model for pinning, are used to get estimates for possible applications of thin film ternary superconductors where high current densities are needed in the presence of high magnetic fields. The normal state experimental data is used to derive several Fermi surface parameters, e.g. the Fermi velocity and the effective Fermi surface area. (orig.)

  12. The endometrium in assisted reproductive technology: How thin is thin?

    OpenAIRE

    Nalini Mahajan; Sharma, S.

    2016-01-01

    A thin endometrium is encountered infrequently (2.4%) in assisted reproductive technology cycles. When it does occur it is a cause of concern as it is associated with lower implantation rate and pregnancy rate. Though pregnancies have been reported at 4 and 5 mm it is apparent that an endometrial thickness

  13. Enhanced multiferroic properties in (1–y)BiFeO3–yNi0.50Cu0.05Zn0.45Fe2O4 composites

    International Nuclear Information System (INIS)

    Multiferroic composites (1–y)BiFeO3–yNi0.50Cu0.05Zn0.45Fe2O4 (y=0.0, 0.1, 0.2, 0.3 and 0.4) are synthesized by the standard solid state reaction method. The X-ray diffraction analysis affirms the formation of both the component phases and also reveals that there is no chemical reaction between them. From the energy-dispersive X-ray spectroscopy study it is observed that the percentage of the elements in the component phases is well consistent with the nominal composition of the composites. Field Emission Scanning Electron Microscopy analysis shows almost homogeneous mixture of the two phases. The real part of the initial permeability increases (up to 67%) and the loss decreases with the ferrite content in the composites which is important in application point of view. Dielectric constant (ε′), loss tangent and AC conductivity are measured as a function of frequency at room temperature. The highest ε′ is obtained for 0.6BiFeO3–0.4Ni0.50Cu0.05Zn0.45Fe2O4 composite. The dielectric dispersion at lower frequency (<105 Hz) is due to the interfacial polarization. The complex impedance spectroscopy is used to correlate between the electrical properties of the studied samples with their microstructures. Two semicircular arcs corresponding to both grain and grain boundary contribution to electrical properties have been observed in all the studied samples. The maximum magnetoelectric voltage coefficient is found to be ∼38 mV cm−1 Oe−1 for the composite with 80% ferroelectric+20% ferrite phases. The present composite might be a promising candidate as multiferroic materials showing effective electric and magnetic properties. - Highlights: • XRD shows coexistance of ferroelectric and ferrimagnetic phases and no third phase. • The multiferroic composites show enhanced initial permeability and low loss. • Dielectric constant exhibits excellent high frequency stability. • Enhanced ME effect (∼38 mVcm−1Oe−1) is observed for 0.8BFO–0.2NCZFO composite

  14. Multiferroic and magnetoelectric properties of CoFe{sub 2}O{sub 4}/Pb{sub 1−x}Sr{sub x}TiO{sub 3} composite films

    Energy Technology Data Exchange (ETDEWEB)

    Negi, N. S., E-mail: nainjeet12@gmail.com; Bala, Kanchan [Department of Physics, Himachal Pradesh University, Shimla 171005 (India); Yadav, Akash; Kotnala, R. K. [CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India)

    2015-04-28

    To realize multiferroic and magnetoelectric properties, bi-layered nanocomposite films consisting of CoFe{sub 2}O{sub 4} (CFO)/Pb{sub 1−x}Sr{sub x}TiO{sub 3} (PST) phases (x = 0.1, 0.2, and 0.3) have been deposited on Pt/TiO{sub 2}/SiO{sub 2}/Si substrate by using a metallo-organic decomposition process. Both the PST perovskite and the CFO spinel phases are confirmed from X-ray diffraction patterns and Raman spectra of the composite films. The composite films exhibit room temperature multiferroic properties. The values of saturation magnetization (M{sub s}), remanent magnetization (M{sub r}), and coercive field (H{sub c}) of the composite films are in the range of 108–119 kA/m, 42–51 kA/m, and 44.5–64.1 kA/m, respectively. In addition, the saturation polarization (P{sub s}), remanent polarization (P{sub r}), and electrical coercive field (E{sub c}) are observed in the range of 11.3–14.4 μC/cm{sup 2}, 2.9–4.8 μC/cm{sup 2}, and 56–59.5 kV/cm, respectively. The dielectric response in the presence of applied magnetic field, H{sub dc} ∼ 238.6 kA/m shows a high magnetocapacitance value ∼385% at frequency 100 kHz for CFO/PST composite film with x = 0.1. The maximum magnetoelectric voltage co-efficient value, α{sub E} ∼ 380 kV/(m × T) has been achieved in the composite films with x = 0.1. The influence of elastic/and or interfacial strain on multiferroic magnetoelectric properties is evident from the results.

  15. Lead nitroprusside: A new precursor for the synthesis of the multiferroic Pb{sub 2}Fe{sub 2}O{sub 5,} an anion-deficient perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Gil, Diego M. [Instituto de Química Inorgánica, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 471, 4000 San Miguel de Tucumán (Argentina); Nieva, Gladys [Centro Atómico Bariloche, Instituto Balseiro, Comisión Nacional de Energía Atómica, Universidad Nacional de Cuyo, 8400 San Carlos de Bariloche (Argentina); Franco, Diego G. [Centro Atómico Bariloche, Instituto Balseiro, Comisión Nacional de Energía Atómica, Universidad Nacional de Cuyo, 8400 San Carlos de Bariloche (Argentina); Instituto de Investigaciones en Fisicoquímica de Córdoba (INFIQC – CONICET), Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba (Argentina); Gómez, María Inés [Instituto de Química Inorgánica, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 471, 4000 San Miguel de Tucumán (Argentina); and others

    2013-08-15

    In order to investigate the formation of multiferroic oxide Pb{sub 2}Fe{sub 2}O{sub 5}, the thermal decomposition of Pb[Fe(CN){sub 5}NO] has been studied. The complex precursor and the thermal decomposition products were characterized by IR and Raman spectroscopy, thermal analysis, powder X-ray diffraction (PXRD), scanning electron microscopy and magnetic measurements. The crystal structure of Pb[Fe(CN){sub 5}NO] was refined by Rietveld analysis. It crystallizes in the orthorhombic system, space group Pnma. The thermal decomposition in air produces highly pure Pb{sub 2}Fe{sub 2}O{sub 5} as final product. This oxide is an anion deficient perovskite with an incommensurate superstructure. The magnetic measurements confirm that Pb{sub 2}Fe{sub 2}O{sub 5} shows a weak ferromagnetic signal probably due to disorder in the perfect antiferromagnetic structure or spin canting. The estimated ordering temperature from the fit of a phenomenological model was 520 K. The SEM images reveal that the thermal decomposition of Pb[Fe(CN){sub 5}NO] produces Pb{sub 2}Fe{sub 2}O{sub 5} with small particle size. - Highlights: • Pb[Fe(CN){sub 5}NO] was synthesized and characterized. • Pb[Fe(CN){sub 5}NO] belongs to orthorhombic crystal system, space group Pnma. • Pb{sub 2}Fe{sub 2}O{sub 5} was obtained by thermal decomposition of Pb[Fe(CN){sub 5}NO]. • Pb{sub 2}Fe{sub 2}O{sub 5} is a weak ferromagnet due to spin canting. • Ordering temperature of Pb{sub 2}Fe{sub 2}O{sub 5} from the fit of a phenomenological model was 520 K. - Graphical abstract: Field cooling (FC) and zero field cooling (ZFC) magnetization curves at H = 10 and 1000 Oe for Pb{sub 2}Fe{sub 2}O{sub 5} obtained at 750 °C. Remnant magnetization after applying H = 1 T, FC procedure at 0.8 Oe. The fitted expression (see text) yield an ordering temperature T{sub o} = 520 K. Display Omitted.

  16. Ferromagnetic, ferroelectric and dielectric properties of Pb(Zr0.53Ti0.47)O3/CoFe2O4 multiferroic composite thick films

    International Nuclear Information System (INIS)

    Pb(Zr0.53Ti0.47)O3/CoFe2O4 (abbreviated as PZT/CFO) multiferroic composite thick films have been prepared on the Pt/Ti/SiO2/Si substrate by using a hybrid sol-gel process. The thick films were finally annealed at 650 0C in air and the ferromagnetic, ferroelectric and dielectric properties of these films were investigated. Both the PZT pervoskite phase and the CFO spinel phase were detected from x-ray diffraction. The thickness of the film was measured to be about 3.55 μm using a surface profiler and was confirmed with scanning electron microscopy. Effective saturated magnetization (Mes) estimated from the measured saturated magnetization (Ms) was defined and the result shows that the Mes of the film fabricated in this work is larger than that of the thickest PZT/CFO film reported so far, so are the coercive magnetic fields (Hc). The properties of the films can be attributed to less constraints from the substrate to the composite thick films. The remanent polarization (Pr) of 12.5 μC cm-2 is comparable to that of the thickest PZT/CFO film reported so far due to the lack of polyvinylpyrrolidone (PVP), while the coercive electric field (Ec) of 252.8 kV cm-1 is much larger than it. In addition, the PZT/CFO thick films exhibit a smaller dielectric permittivity of about 200 within the whole measured frequency range due to the introduction of the low dielectric permittivity CFO phase. Furthermore, dielectric loss decreases to ∼0.01 with increasing frequency to 1 MHz, even lower than that of the PZT thick films. Although the ferroelectric properties and the dielectric constant of the PZT/CFO thick film were degraded compared with a pure PZT thick film, the coexistence of a promising ferromagnetic and ferroelectric response with a lower loss indicated that the PZT/CFO film is a good candidate for future applications in a reasonably high frequency range.

  17. Stability of charged thin shells

    International Nuclear Information System (INIS)

    In this article we study the mechanical stability of spherically symmetric thin shells with charge, in Einstein-Maxwell and Einstein-Born-Infeld theories. We analyze linearized perturbations preserving the symmetry, for shells around vacuum and shells surrounding noncharged black holes.

  18. Size effects in thin films

    CERN Document Server

    Tellier, CR; Siddall, G

    1982-01-01

    A complete and comprehensive study of transport phenomena in thin continuous metal films, this book reviews work carried out on external-surface and grain-boundary electron scattering and proposes new theoretical equations for transport properties of these films. It presents a complete theoretical view of the field, and considers imperfection and impurity effects.

  19. Capillary thinning of polymeric filaments

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Szabo, Peter

    1999-01-01

    The capillary thinning of filaments of a Newtonian polybutene fluid and a viscoelastic polyisobutylene solution are analyzed experimentally and by means of numerical simulation. The experimental procedure is as follows. Initially, a liquid sample is placed between two cylindrical plates. Then, th...

  20. Capillary thinning of polymeric filaments

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Szabo, Peter; Hassager, Ole

    The capillary thinning of a polymeric filament is analysed experimentally as well as by means of numerical simulation. The experimental procedure is as follows. Initially a liquid sample is kept between two cylindrical plates. Then the bottom plate is lowered under gravity to yield a given strain...