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Sample records for bi2fecro6 multiferroic thin

  1. 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.

  2. 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.

  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. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. Magnetoelectric coupling of multiferroic chromium doped barium titanate thin film probed by magneto-impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Jyoti, E-mail: shah.jyoti1@gmail.com; Kotnala, Ravinder K., E-mail: rkkotnala@nplindia.org, E-mail: rkkotnala@gmail.com [Multiferroic and Magnetics Laboratory, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India)

    2014-04-07

    Thin film of BaTiO{sub 3} doped with 0.1 at. % Cr (Cr:BTO) has been prepared by pulsed laser deposition technique. Film was deposited on Pt/SrTiO{sub 3} substrate at 500 °C in 50 mTorr Oxygen gas pressure using KrF (298 nm) laser. Polycrystalline growth of single phase Cr:BTO thin film has been confirmed by grazing angle X-ray diffraction. Cr:BTO film exhibited remnant polarization 6.4 μC/cm{sup 2} and 0.79 MV/cm coercivity. Magnetization measurement of Cr:BTO film showed magnetic moment 12 emu/cc. Formation of weakly magnetic domains has been captured by magnetic force microscopy. Theoretical impedance equation fitted to experimental data in Cole-Cole plot for thin film in presence of transverse magnetic field resolved the increase in grain capacitance from 4.58 × 10{sup −12} to 5.4 × 10{sup −11} F. Film exhibited high value 137 mV/cm-Oe magneto-electric (ME) coupling coefficient at room temperature. The high value of ME coupling obtained can reduce the typical processing steps involved in multilayer deposition to obtain multiferrocity in thin film. Barium titanate being best ferroelectric material has been tailored to be multiferroic by non ferromagnetic element, Cr, doping in thin film form opens an avenue for more stable and reliable spintronic material for low power magnetoelectric random excess memory applications.

  13. 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.

  14. 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.

  15. 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.)

  16. 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

  17. 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.

  18. 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

  19. 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

    2016-08-01

    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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Multiferroic YCrO3 thin films grown on glass substrate: Resistive switching characteristics

    Science.gov (United States)

    Seo, Jeongdae; Ahn, Yoonho; Son, Jong Yeog

    2016-01-01

    Polycrystalline YCrO3 thin films were deposited on (111) Pt/Ta/glass substrates by pulsed laser deposition. The YCrO3 thin films exhibited good ferroelectric properties with remnant polarization of about 5 µC/cm2. Large leakage current was observed by I- V curve and ferroelectric hysteresis loop. The YCrO3 resistive random access memory (RRAM) capacitor showed unipolar switching behaviors with SET and RESET voltages higher than those of general NiO RRAM capacitors. [Figure not available: see fulltext.

  5. 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.

  6. 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.

  7. Analysis of multiferroic properties in BiMnO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Grizalez, M [Universidad de la Amazonia, Florencia (Colombia); Mendoza, G A [Department of Physics, Universidad Nacional de Colombia, Bogota (Colombia); Prieto, P, E-mail: pprieto@calima.univalle.edu.c [Center of Excellence on Novel Materials - CENM (Colombia)

    2009-05-01

    Textured BiMnO{sub 3} [111] thin films on SrTiO{sub 3} (100) and Pt/TiO{sub 2}/SiO{sub 2} substrates were grown via r.f. magnetron sputtering (13.56 MHz). The XRD spectra confirmed a monoclinic structure and high-quality textured films for the BiMnO{sub 3} films. The films grown on SrTiO{sub 3} (100) showed higher crystalline quality than those developed on Pt/TiO{sub 2}/SiO{sub 2}. Through optimized oxygen pressure of 5x10{sup -2} mbar during the r.f. sputtering deposition, the crystalline orientation of the BiMnO{sub 3} film was improved with respect to the previously reported value of 2x10{sup -1} mbar. The values of spontaneous polarization (P{sub s}), remnant polarization (P{sub r}), and coercive field (F{sub c}) from ferroelectric hysteresis loops (P-E) at different temperatures were also obtained. Samples with higher crystalline order revealed better dielectric properties (high P{sub s} and P{sub r} values and a low F{sub c}). For films on both types of substrates, the ferroelectric behavior was found to persist up to 400K. Measurements at higher temperatures were difficult to obtain given the increased conductivity of the films. Magnetic hysteresis loops from 5K to 120K were obtained for BiMnO{sub 3} films grown on SrTiO{sub 3} and Pt/TiO{sub 2}/SiO{sub 2} substrates. The results suggested that the coexistence of the magnetic and electric phases persists up to 120K.

  8. 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.

  9. 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.

  10. Engineering Nanoscale Multiferroic Composites for Memory Applications with Atomic Layer Deposition of Pb(ZrxTi1-x)O3 Thin Films

    Science.gov (United States)

    Chien, Diana

    This work focuses on the development of atomic layer deposition (ALD) for lead zirconate titanate, Pb(ZrxTi1-x)O 3 (PZT). Leveraging the surface-reaction controlled process based on alternating self-limiting surface reactions, PZT can be synthesized not only with elemental precision to realize the desired composition (Zr/Ti = 52/48) but also with outstanding conformality. The latter enables the integration of PZT with a ferromagnetic phase to realize multiferroism (MF) and magnetoelectric (ME) effect. Since PZT is one of the best known ferroelectric and piezoelectric materials due the large displacements of the Pb ions at the morphotropic phase boundary, PZT based MF composites could lead to stronger ME coupling through strain coupling at the interface. Specifically, ALD PZT thin films were synthesized by using beta-diketonate metalorganic precursors Pb(TMHD)2, Zr(TMHD)4, and Ti(O.i-Pr) 2(TMHD)2 and H2O. The number of local cycles and global cycles were regulated to achieve the desired stoichiometry and thickness, respectively. ALD of PZT was studied to obtain (100) textured PZT on Pt (111) oriented platinized silicon substrates. In order to attain a highly oriented PZT thin film, a (100) textured PbTiO3 seed layer was required because PZT orientation is governed by nucleation. MF nanocomposites were engineered using ALD PZT thin films to achieve controlled complex nanoscale structures, enabling porosity to be studied as a new additional parameter for nanocomposite architectures to enhance ME effect. Specifically, 3--6 nm-thick ALD PZT thin films were deposited to uniformly coat the walls of mesoporous cobalt ferrite (CFO) template. The PZT/CFO nanocomposites were electrically poled ex-situ and the change in magnetic moment was measured. The inverse magnetoelectric coupling coefficient, a, was determined to be 85.6 Oe-cm/mV. The in-plane results show no significant change in magnetization (1--4%) as a function of electric field, which was expected due to the effect

  11. 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.

  12. 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...

  13. 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...

  14. 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)

  15. 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.

  16. 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.

  17. Multiferroic grain boundaries in oxygen-deficient ferroelectric lead titanate.

    Science.gov (United States)

    Shimada, Takahiro; Wang, Jie; Ueda, Taku; Uratani, Yoshitaka; Arisue, Kou; Mrovec, Matous; Elsässer, Christian; Kitamura, Takayuki

    2015-01-14

    Ultimately thin multiferroics arouse remarkable interest, motivated by the diverse utility of coexisting ferroelectric and (anti)ferromagnetic order parameters for novel functional device paradigms. However, the ferroic order is inevitably destroyed below a critical size of several nanometers. Here, we demonstrate a new path toward realization of atomically thin multiferroic monolayers while resolving a controversial origin for unexpected "dilute ferromagnetism" emerged in nanocrystals of nonmagnetic ferroelectrics PbTiO3. The state-of-the-art hybrid functional of Hartree-Fock and density functional theories successfully identifies the origin and underlying physics; oxygen vacancies interacting with grain boundaries (GBs) bring about (anti)ferromagnetism with localized spin moments at the neighboring Ti atoms. This is due to spin-polarized defect states with broken orbital symmetries at GBs. In addition, the energetics of oxygen vacancies indicates their self-assembling nature at GBs resulting in considerably high concentration, which convert the oxygen-deficient GBs into multiferroic monolayers due to their atomically thin interfacial structure. This synthetic concept that realizes multiferroic and multifunctional oxides in a monolayered geometry through the self-assembly of atomic defects and grain boundary engineering opens a new avenue for promising paradigms of novel functional devices. PMID:25485474

  18. 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.

  19. 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

  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. Voltage control of the magnetic coercive field: Multiferroic coupling or artifact?

    Science.gov (United States)

    Vopsaroiu, M.; Cain, M. G.; Woolliams, P. D.; Weaver, P. M.; Stewart, M.; Wright, C. D.; Tran, Y.

    2011-03-01

    The ability to dynamically tune the coercive field of magnetic thin films is a powerful tool for applications, including in magnetic recording disk technologies. Recently, a number of papers have reported the electrical voltage control of the coercive field of various magnetic thin films in multiferroic composites. Theoretically, this is possible in magneto-electric (ME) multiferroics due to the piezoferroelectric component that can be electrically activated to dynamically modify the properties of the magnetic component of the composite via a direct or strain mediated ME coupling. In this paper we fabricated and examined such structures and we determined that the magnetic coercive field reduction is most likely due to a heating effect. We concluded that this effect is probably an artifact that cannot be attributed to a multiferroic coupling.

  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. 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.

  5. 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

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

    NARCIS (Netherlands)

    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 mi

  7. Voltage control of magnetism in multiferroic heterostructures.

    Science.gov (United States)

    Liu, Ming; Sun, Nian X

    2014-02-28

    Electrical tuning of magnetism is of great fundamental and technical importance for fast, compact and ultra-low power electronic devices. Multiferroics, simultaneously exhibiting ferroelectricity and ferromagnetism, have attracted much interest owing to the capability of controlling magnetism by an electric field through magnetoelectric (ME) coupling. In particular, strong strain-mediated ME interaction observed in layered multiferroic heterostructures makes it practically possible for realizing electrically reconfigurable microwave devices, ultra-low power electronics and magnetoelectric random access memories (MERAMs). In this review, we demonstrate this remarkable E-field manipulation of magnetism in various multiferroic composite systems, aiming at the creation of novel compact, lightweight, energy-efficient and tunable electronic and microwave devices. First of all, tunable microwave devices are demonstrated based on ferrite/ferroelectric and magnetic-metal/ferroelectric composites, showing giant ferromagnetic resonance (FMR) tunability with narrow FMR linewidth. Then, E-field manipulation of magnetoresistance in multiferroic anisotropic magnetoresistance and giant magnetoresistance devices for achieving low-power electronic devices is discussed. Finally, E-field control of exchange-bias and deterministic magnetization switching is demonstrated in exchange-coupled antiferromagnetic/ferromagnetic/ferroelectric multiferroic hetero-structures at room temperature, indicating an important step towards MERAMs. In addition, recent progress in electrically non-volatile tuning of magnetic states is also presented. These tunable multiferroic heterostructures and devices provide great opportunities for next-generation reconfigurable radio frequency/microwave communication systems and radars, spintronics, sensors and memories.

  8. 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

  9. 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).

  10. 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

  11. 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.

  12. 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.

  13. 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...

  14. 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.

  15. Graphene-multiferroic interfaces for spintronics applications

    Science.gov (United States)

    Zanolli, Zeila

    2016-08-01

    Graphene and magnetoelectric multiferroics are promising materials for spintronic devices with high performance and low energy consumption. A very long spin diffusion length and high carrier mobility make graphene attractive for spintronics. The coupling between ferroelectricity and magnetism, which characterises magnetoelectrics, opens the way towards unique device architectures. In this work, we combine the features of both materials by investigating the interface between graphene and BaMnO3, a magnetoelectric multiferroic. We show that electron charge is transferred across the interface and magnetization is induced in the graphene sheet due to the strong interaction between C and Mn. Depending on the relative orientation of graphene and BaMnO3, a quasi-half-metal or a magnetic semiconductor can be obtained. A remarkably large proximity induced spin splitting of the Dirac cones (~300 meV) is achieved. We also show how doping with acceptors can make the high-mobility region of the electronic bands experimentally accessible. This suggests a series of possible applications in spintronics (e.g. spin filters, spin injectors) for hybrid organic-multiferroic materials and reveals hybrid organic-multiferroics as a new class of materials that may exhibit exotic phenomena such as the quantum anomalous Hall effect and a Rashba spin-orbit induced topological gap.

  16. 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.

  17. Thermal conductivity and multiferroics of electroactive polymers and polymer composites

    Science.gov (United States)

    Jin, Jiezhu

    Electronically conducting polymers and electromechanical polymers are the two important branches of the cutting-edge electroactive polymers. They have shown significant impact on many modern technologies such as flat panel display, energy transport, energy conversion, sensors and actuators. To utilize conducting polymers in microelectronics, optoelectronics and thermoelectrics, it is necessary to have a comprehensive study of their thermal conductivity since thermal conductivity is a fundamental materials property that is particularly important and sometimes a determining factor of the device performance. For electromechanical polymers, larger piezoelectric effect will contribute to the improvement of magnetoelectric (ME) coupling efficiency in their multiferroic composites. This dissertation is devoted to characterizing electronically conducting polymers for their electrical and thermal conductivity, and developing new classes of electromechanical polymers and strain-mediated electromechanical polymer-based multiferroic ME composites. Conducting polymers opened up new possibilities for devices combining novel electrical and thermal properties, but there has been limited understanding of the length-scale effect of the electrical and thermal conductivity, and the mechanism underlying the electricity and heat transport behavior. In this dissertation, the analytical model and experimental technique are presented to measure the in-plane thermal conductivity of polyaniline thin films. For camphorsulfonic acid doped polyaniline patterned on silicon oxide/silicon substrate using photolithography and reactive ion etching, the thermal conductivity of the film with thickness of 20 nm is measured to be 0.0406 W/m˙K, which significantly deviates from their bulk (> 0.26 W/m˙K). The size effect on thermal conductivity at this scale is attributed to the significant phonon boundary scattering. When the film goes up to 130 nm thick, the thermal conductivity increases to 0.166 W

  18. 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...

  19. High pressure and multiferroics materials: a happy marriage.

    Science.gov (United States)

    Gilioli, Edmondo; Ehm, Lars

    2014-11-01

    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.

  20. 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.

  1. 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.

  2. Hexagonal phase stabilization and magnetic orders of multiferroic L u1 -xS cxFe O3

    Science.gov (United States)

    Lin, L.; Zhang, H. M.; Liu, M. F.; Shen, Shoudong; Zhou, S.; Li, D.; Wang, X.; Yan, Z. B.; Zhang, Z. D.; Zhao, Jun; Dong, Shuai; Liu, J.-M.

    2016-02-01

    Hexagonal LuFe O3 has drawn a lot of research attention due to its contentious room-temperature multiferroicity. Due to the instability of hexagonal phase in the bulk form, most experimental studies focused on LuFe O3 thin films which can be stabilized by strain using proper substrates. Here we report on the hexagonal phase stabilization, magnetism, and magnetoelectric coupling of bulk LuFe O3 by partial Sc substitution of Lu. First, our first-principles calculations show that the hexagonal structure can be stabilized by partial Sc substitution, while the multiferroic properties, including the noncollinear magnetic order and geometric ferroelectricity, remain robustly unaffected. Therefore, L u1 -xS cxFe O3 can act as a platform to check the multiferroicity of LuFe O3 and related materials in the bulk form. Second, the magnetic characterizations on bulk L u1 -xS cxFe O3 demonstrate a magnetic anomaly (probable antiferromagnetic ordering) above room temperature, ˜425-445 K, followed by magnetic transitions in low temperatures (˜167-172 K). In addition, a magnetoelectric response is observed in the low-temperature region. Our study provides useful information on the multiferroic physics of hexagonal R Fe O3 and related systems.

  3. 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.

  4. 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...

  5. 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.

  6. New design strategy for realizing multiferroic materials

    Science.gov (United States)

    Puggioni, Danilo; Giovannetti, Gianluca; Capone, Massimo; Rondinelli, James

    Ferroelectricity is a property that only insulating materials can exhibit. For this reason, nearly all searches for new multiferroic compounds, those simultaneously exhibiting ferroelectric and magnetic order, have focused on insulating magnetic oxides. Here, we propose a different approach: Start from a conducting oxide with broken inversion symmetry and search for routes to induce long-range magnetic order. Using density-functional and dynamical mean-field theories, we investigate the electronic properties of the polar metallic oxide LiOsO3. We show that a multiferroic state can be engineered by enclosing LiOsO3 between an insulating material, LiNbO3. We predict that the 1/1 superlattice of LiOsO3 and LiNbO3 exhibits strong coupling between magnetic and ferroelectric degrees of freedom with a ferroelectric polarization of 41.2 μCcm-2, Curie temperature of 927 K, and Néel temperature of 379 K. Our results show that one can start with polar metallic oxides to make multiferroics.

  7. 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)

  8. Deterministic control of ferroelastic switching in multiferroic materials

    NARCIS (Netherlands)

    Balke, N.; Choudhury, S.; Jesse, S.; Huijben, M.; Chu, Y.-H.; Baddorf, A.P.; Chen, L.Q.; Ramesh, R.; Kalinin, S.V.

    2009-01-01

    Multiferroic materials showing coupled electric, magnetic and elastic orderings provide a platform to explore complexity and new paradigms for memory and logic devices. Until now, the deterministic control of non-ferroelectric order parameters in multiferroics has been elusive. Here, we demonstrate

  9. 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.

  10. Multi-ferroic and magnetoelectric materials and interfaces.

    Science.gov (United States)

    Velev, J P; Jaswal, S S; Tsymbal, E Y

    2011-08-13

    The existence of multiple ferroic orders in the same material and the coupling between them have been known for decades. However, these phenomena have mostly remained the theoretical domain owing to the fact that in single-phase materials such couplings are rare and weak. This situation has changed dramatically recently for at least two reasons: first, advances in materials fabrication have made it possible to manufacture these materials in structures of lower dimensionality, such as thin films or wires, or in compound structures such as laminates and epitaxial-layered heterostructures. In these designed materials, new degrees of freedom are accessible in which the coupling between ferroic orders can be greatly enhanced. Second, the miniaturization trend in conventional electronics is approaching the limits beyond which the reduction of the electronic element is becoming more and more difficult. One way to continue the current trends in computer power and storage increase, without further size reduction, is to use multi-functional materials that would enable new device capabilities. Here, we review the field of multi-ferroic (MF) and magnetoelectric (ME) materials, putting the emphasis on electronic effects at ME interfaces and MF tunnel junctions. PMID:21727115

  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. Reliable switching in MRAM and multiferroic logic

    Science.gov (United States)

    Munira, Kamaram; Bandyopadhyay, Supriyo; Atulasimha, Jayasimha; Chen, Eugene; Ghosh, Avik W.

    2012-02-01

    Low reliable writing in spintronic devices limits their applicability in the automotive and defense industries. Coupling stochastic macromagnetic simulator with quantum transport, we show how greater reliable switching can be achieved in MRAM and multiferroic logic. Using a combination of spin-transfer torque and small applied perpendicular field in MRAM, the error rate can be considerably reduced for a given voltage pulse. In multiferroic logic, strain plays the role of the magnetic field. Information is passed along an array of nanomagnets (NM) (magnetostrictive + piezoelectric layers) through dipole coupling with neighboring NMs. A low voltage applied to the piezoelectric element causes the NM's magnetization to switch to its hard axis. Upon releasing the stress, the magnetization of the NM relaxes to the easy axis, with its final orientation determined by the dipolar coupling with the left NM, thus achieving a low power Bennett clocked computation. In the face of stagnation points along the potential energy landscape, the success rate of the straintronic switching can be controlled with by how fast the stress is removed from the NM. (Funding: DARPA, GRANDIS, NSF-NEB).

  13. 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.

  14. 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.

  15. 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.

  16. Landau model for the multiferroic delafossite antiferromagnets

    Science.gov (United States)

    Ribeiro, J. L.; Perez-Mato, J. M.; Vieira, L. G.

    2016-10-01

    A symmetry based framework is used to describe the complex phase diagrams observed in the multiferroic delafossite compounds. A free energy Landau functional is derived from the analysis of the transformation properties of the most general incommensurate magnetic spin order parameter. A principle of maximal symmetry is invoked and the stability of each of the different higher symmetry phases considered. The competition between different potential ground states is analysed within the scope of a simplified model, which emphasizes the role of the symmetry allowed phase dependent biquadratic couplings. The cross-over between the different competing states is also discussed. The results show that the diverse set of phase diagrams that are experimentally observed in this class of triangular lattice antiferromagnets and, in particular, the stabilization of magnetically induced ferroelectric states, can be well interpreted and described within this integrated phenomenological approximation.

  17. 多铁性十年回眸%Decade of multiferroic researches

    Institute of Scientific and Technical Information of China (English)

    刘俊明; 南策文

    2014-01-01

    多铁性研究可上溯至1950年代,作为凝聚态与材料物理的一个研究方向也算历史悠久;但大规模研究则主要受2003年两项里程碑性成果驱动,距今正好十年。所谓“十年树木”,古训赋予我们回眸十年多铁研究的一个理由。这两项成果之一是BiFeO3外延薄膜制备及磁电耦合观测,主要贡献在于将互无交叠的磁电耦合唯象理论与多铁性微观物理框架通过铁性畴层次有机结合,触发多铁性薄膜与异质结的广泛研究。另一项成果是发现TbMnO3中巨大的磁电耦合效应,开启探索一大类具有崭新物理内涵的多铁性物质之路。对多铁性薄膜异质结的研究深入细致,体现了层层盘剥、细嚼慢咽的风格。而单相多铁性的探索则百花齐放、只争朝夕。前者如能工巧匠,其足迹是精湛研究技术方法与物理理论相结合的图画。后者如春潮奔腾,所到之处气象万千,其大观是科学发现与新材料探索的范例。文章基于粗略框架,对多铁性研究十年图景粗作描绘。有关多铁性各方面的详细论述则见诸本专题之隽文秀语。多铁性研究经历分而春秋的黄金十年,正出现久分必合的迹象,令人不忍释手。%Multiferroicity as one of favorable topics in condensed matters and materials physics has been receiving attentions since 1950s. Intensive research activities, however, were re-vived by two milestones as accomplished in 2003, sustaining for more than ten years. One of the milestones is the preparation of epitaxial BiFeO3 thin films and demonstration of the magnetoelec-tric effect. The physics at the multiferroic domain level is believed to fill the gap between the phe-nomenological theories and microscopic mechanisms. The other goes to the colossal magnetoelec-tric effect in manganite TbMnO3, which has paved a roadmap towards a class of multiferroic com-pounds with substantial significance of physics

  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. 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.

  20. 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

  1. Synthesis of Multiferroic BiFeO3

    Institute of Scientific and Technical Information of China (English)

    WU; Mei-mei; WANG; Wei; LIU; Rong-deng; LIU; Yun-tao; CHEN; Dong-feng

    2012-01-01

    <正>Multiferroic materials exhibit simultaneous presence of ferroelectricity, ferromagnetism and ferroelasticity in the same phase, and have potential applications in information storage, spintronics, sensors etc. BiFeO3 is one such material with ferroelectric and antiferromagnetic behavior above room

  2. The origin of photovoltaic responses in BiFeO3 multiferroic ceramics.

    Science.gov (United States)

    Tu, C-S; Hung, C-M; Schmidt, V H; Chien, R R; Jiang, M-D; Anthoninappen, J

    2012-12-12

    Multiferroic BiFeO(3) (BFO) ceramics with electrodes of indium tin oxide (ITO) and Au thin films exhibit significant photovoltaic effects under near-ultraviolet illumination (λ = 405 nm) and show strong dependences on light wavelength, illumination intensity, and sample thickness. The correlation between photovoltaic responses and illumination intensity can be attributed to photo-excited and thermally generated charge carriers in the interface depletion region between BFO ceramic and ITO thin film. A theoretical model is developed to describe the open-circuit photovoltage and short-circuit photocurrent density as a function of illumination intensity. This model can be applied to the photovoltaic effects in p-n junction type BFO thin films and other systems. The BFO ceramic exhibits stronger photovoltaic responses than the ferroelectric Pb(1-x)La(x)(Zr(y)Ti(1-y))(1-x/4)O(3) (PLZT) ceramics under near-ultraviolet illumination. Comparisons are made with other systems and models for the photovoltaic effect.

  3. 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.

  4. 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.

  5. 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.

  6. Modeling of efficient solid-state cooler on layered multiferroics.

    Science.gov (United States)

    Starkov, Ivan; Starkov, Alexander

    2014-08-01

    We have developed theoretical foundations for the design and optimization of a solid-state cooler working through caloric and multicaloric effects. This approach is based on the careful consideration of the thermodynamics of a layered multiferroic system. The main section of the paper is devoted to the derivation and solution of the heat conduction equation for multiferroic materials. On the basis of the obtained results, we have performed the evaluation of the temperature distribution in the refrigerator under periodic external fields. A few practical examples are considered to illustrate the model. It is demonstrated that a 40-mm structure made of 20 ferroic layers is able to create a temperature difference of 25K. The presented work tries to address the whole hierarchy of physical phenomena to capture all of the essential aspects of solid-state cooling.

  7. Multiferroic materials based on organic transition-metal molecular nanowires.

    Science.gov (United States)

    Wu, Menghao; Burton, J D; Tsymbal, Evgeny Y; Zeng, Xiao Cheng; Jena, Puru

    2012-09-01

    We report on the density functional theory aided design of a variety of organic ferroelectric and multiferroic materials by functionalizing crystallized transition-metal molecular sandwich nanowires with chemical groups such as -F, -Cl, -CN, -NO(2), ═O, and -OH. Such functionalized polar wires exhibit molecular reorientation in response to an electric field. Ferroelectric polarizations as large as 23.0 μC/cm(2) are predicted in crystals based on fully hydroxylized sandwich nanowires. Furthermore, we find that organic nanowires formed by sandwiching transition-metal atoms in croconic and rhodizonic acids, dihydroxybenzoquinone, dichloro-dihydroxy-p-benzoquinone, or benzene decorated by -COOH groups exhibit ordered magnetic moments, leading to a multiferroic organometallic crystal. When crystallized through hydrogen bonds, the microscopic molecular reorientation translates into a switchable polarization through proton transfer. A giant interface magnetoelectric response that is orders of magnitude greater than previously reported for conventional oxide heterostructure interfaces is predicted. PMID:22881120

  8. 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

  9. 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...

  10. 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...

  11. 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.

  12. Photocreating supercooled spiral-spin states in a multiferroic manganite

    Science.gov (United States)

    Sheu, Y. M.; Ogawa, N.; Kaneko, Y.; Tokura, Y.

    2016-08-01

    We demonstrate that the dynamics of the a b -spiral-spin order in a magnetoelectric multiferroic Eu0.55Y0.45MnO3 can be unambiguously probed through optical second harmonic signals, generated via spin-induced ferroelectric polarization. In the case of weak excitation, the ferroelectric and the spiral-spin order remains interlocked, both relaxing through spin-lattice relaxation in the nonequilibrium state. When the additional optical pulse illuminating the sample is intense enough to induce a local phase transition thermally, the system creates a metastable state of the b c -spiral-spin order (with the electric polarization P ∥c ) via supercooling across the first-order phase transition between the a b and b c spiral. The supercooled state of the b c -spiral spin is formed in the thermodynamical ground state of the a b spiral (P ∥a ), displaying a prolonged lifetime with strong dependence on the magnetic field along the a axis. The observed phenomena provide a different paradigm for photoswitching between the two distinct multiferroic states, motivating further research into a direct observation of the photocreated supercooled b c -spiral spin in multiferroic manganites.

  13. Nanoscale structural modulation and enhanced room-temperature multiferroic properties.

    Science.gov (United States)

    Sun, Shujie; Huang, Yan; Wang, Guopeng; Wang, Jianlin; Fu, Zhengping; Peng, Ranran; Knize, Randy J; Lu, Yalin

    2014-11-21

    Availability of a single-phase multiferroic material functional at room temperature poses a big challenge, although it is very important to both fundamental physics and application development. Recently, layered Aurivillius oxide materials, one of the most promising candidates, have attracted considerable interest. In this work, we investigated the nanoscale structural evolution of the six-layer Bi7Fe(3-x)Co(x)Ti3O21 when substituting excessive Co. Nanoscale structural modulation (NSM) occurred at the boundaries when changing the material gradually from the originally designed six-layer nanoscale architecture down to five and then four, when increasing the Co content, inducing a previously unidentified analogous morphotropic transformation (AMT) effect. The AMT's net contribution to the enhanced intrinsic multiferroic properties at room temperature was confirmed by quantifying and deducting the contribution from the existing impurity phase using derivative thermo-magneto-gravimetry measurements (DTMG). Significantly, this new AMT effect may be caused by a possible coupling contribution from co-existing NSM phases, indicating a potential method for realizing multiferroic materials that function at room temperature.

  14. 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.

  15. 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.

  16. 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

  17. Oxyhalides: A new class of high-T C multiferroic materials.

    Science.gov (United States)

    Zhao, Li; Fernández-Díaz, Maria Teresa; Tjeng, Liu Hao; Komarek, Alexander C

    2016-05-01

    Magnetoelectric multiferroics have attracted enormous attention in the past years because of their high potential for applications in electronic devices, which arises from the intrinsic coupling between magnetic and ferroelectric ordering parameters. The initial finding in TbMnO3 has triggered the search for other multiferroics with higher ordering temperatures and strong magnetoelectric coupling for applications. To date, spin-driven multiferroicity is found mainly in oxides, as well as in a few halogenides. We report multiferroic properties for synthetic melanothallite Cu2OCl2, which is the first discovery of multiferroicity in a transition metal oxyhalide. Measurements of pyrocurrent and the dielectric constant in Cu2OCl2 reveal ferroelectricity below the Néel temperature of ~70 K. Thus, melanothallite belongs to a new class of multiferroic materials with an exceptionally high critical temperature. Powder neutron diffraction measurements reveal an incommensurate magnetic structure below T N, and all magnetic reflections can be indexed with a propagation vector [0.827(7), 0, 0], thus discarding the claimed pyrochlore-like "all-in-all-out" spin structure for Cu2OCl2, and indicating that this transition metal oxyhalide is, indeed, a spin-induced multiferroic material. PMID:27386552

  18. 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.

  19. A neutron diffraction study of RMn2O5 multiferroics

    Science.gov (United States)

    Radaelli, P. G.; Chapon, L. C.

    2008-10-01

    The magnetic properties of RMn2O5 multiferroics as obtained by unpolarized and polarized neutron diffraction experiments are reviewed. We discuss the qualitative features of the magnetic phase diagram in both zero magnetic field and in field and analyze the commensurate magnetic structure and its coupling to an applied electric field. The origin of ferroelectricity is discussed based on calculations of the ferroelectric polarization predicted by different microscopic coupling mechanisms (exchange-striction and cycloidal spin-orbit models). A minimal model containing a small set of parameters is also presented in order to understand the propagation of the magnetic structure along the c-direction.

  20. 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.

  1. 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.

  2. 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.

  3. Monte Carlo simulation of charge mediated magnetoelectricity in multiferroic bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz-Álvarez, H.H. [Universidad de Caldas, Manizales (Colombia); Universidad Nacional de Colombia Sede Manizales, Manizales, Caldas (Colombia); Bedoya-Hincapié, C.M. [Universidad Nacional de Colombia Sede Manizales, Manizales, Caldas (Colombia); Universidad Santo Tomás, Bogotá (Colombia); Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.co [Universidad Nacional de Colombia Sede Manizales, Manizales, Caldas (Colombia)

    2014-12-01

    Simulations of a bilayer ferroelectric/ferromagnetic multiferroic system were carried out, based on the Monte Carlo method and Metropolis dynamics. A generic model was implemented with a Janssen-like Hamiltonian, taking into account magnetoelectric interactions due to charge accumulation at the interface. Two different magnetic exchange constants were considered for accumulation and depletion states. Several screening lengths were also included. Simulations exhibit considerable magnetoelectric effects not only at low temperature, but also at temperature near to the transition point of the ferromagnetic layer. The results match experimental observations for this kind of structure and mechanism.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. Designing room-temperature multiferroic materials in a single-phase solid-solution film

    Science.gov (United States)

    Mao, H. J.; Song, C.; Cui, B.; Peng, J. J.; Li, F.; Xiao, L. R.; Pan, F.

    2016-09-01

    The search for multiferroic materials with simultaneous ferroelectric and ferromagnetic properties in a single phase at room temperature continues to be fuelled from the perspective of developing multifunctional devices. Here we design a single-phase multiferroic La0.67Sr0.33MnO3-BaTiO3 film, which possesses epitaxial single-crystal and solid-solution structure, high magnetic Curie temperature (~640 K) as well as switchable ferroelectric polarization. Moreover, a notable strain-mediated magnetoelectric coupling at room temperature in the way of modulating the magnetism with an external applied voltage is also observed. The synthetic solid-solution multiferroic film may open an extraordinary avenue for exploring a series of room-temperature multiferroic materials.

  9. 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.

  10. 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...

  11. 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.

  12. Magnetoelectric and multiferroic properties in layered 3D transition metal oxides

    Science.gov (United States)

    Hwang, Jungmin

    Functional ferroelectric and magnetic materials have played an important role of modern technology in the sensor or storage device industries. Ferroelectricity and ferromagnetism emerge from different origins. However, it is discovered that these two seemingly unrelated phenomena can actually coexist in materials called multiferroics. Since current trends toward device miniaturization have increased interests in combining electronic and magnetic properies into multifunctional materials, multiferroics have attracted great attention. Ferromagnetic ferroelectric multiferroics are especially fascinating not only because they have both ferroic properties, but also because of the magnetoelectric coupling which leads the interaction between the magnetic and electric polarization. Recent theoretical breakthroughs in understanding the coexistence of magnetic and electrical ordering have regenerated a great interests in research of such magnetoelectric multiferroics. The long-sought control of electric polarization by magnetic fields was recently discovered in 'frustrated magnets', for example the perovskites RMnO3, RMn 2O5 (R: rare earth elements), Ni3V 2O8, delafossite CuFeO2, spinel CoCr2O 4, MnWO4, etc. In this dissertation, I have explored several magnetoelectric materials and multiferroics, which show significant magnetoelectric interactions between electric and magnetic orderings. The objects of my projects are focused on understanding the origins of such magnetoelectric couplings and establishing the magnetic/electric phase diagrams and the spin structures. I believe that my works would help to understand the mechanisms of magnetoelectric effects and multiferroics.

  13. 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.

  14. Engineering multiferroism in CaMnO3.

    Science.gov (United States)

    Bhattacharjee, Satadeep; Bousquet, Eric; Ghosez, Philippe

    2009-03-20

    Structural instabilities of CaMnO3 are investigated from first principles. We point out that, on top of a strong antiferrodistortive instability responsible for its orthorhombic ground state, the cubic perovskite structure of CaMnO3 also exhibits a weak ferroelectric instability. Although ferroelectricity is suppressed by antiferrodistortive motions, we show that it can be favored using strain or chemical engineering in order to make CaMnO3 multiferroic. We finally highlight that the ferroelectric instability of CaMnO3 is Mn-dominated. This illustrates that, contrary to common belief, ferroelectricity and magnetism are not necessarily exclusive but can be driven by the same cation.

  15. 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)

  16. 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.

  17. 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.

  18. Tuning magnetoelectric coupling using porosity in multiferroic nanocomposites of ALD-grown Pb(Zr,Ti)O3 and templated mesoporous CoFe2O4

    Science.gov (United States)

    Chien, Diana; Buditama, Abraham N.; Schelhas, Laura T.; Kang, Hye Yeon; Robbennolt, Shauna; Chang, Jane P.; Tolbert, Sarah H.

    2016-09-01

    In this manuscript, we examine ways to create multiferroic composites with controlled nanoscale architecture. We accomplished this by uniformly depositing piezoelectric lead zirconate titanate (PZT) into templated mesoporous, magnetostrictive cobalt ferrite (CFO) thin films to form nanocomposites in which strain can be transferred at the interface between the two materials. To study the magnetoelectric coupling, the nanostructure was electrically poled ex situ prior to magnetic measurements. No samples showed a change in in-plane magnetization as a function of voltage due to substrate clamping. Out-of-plane changes were observed, but contrary to expectations based on total PZT volume fraction, mesoporous CFO samples partially filled with PZT showed more change in out-of-plane magnetization than the sample with fully filled pores. This result suggests that residual porosity in the composite adds mechanical flexibility and results in greater magnetoelectric coupling.

  19. Microfluidic synthesis of multiferroic Janus particles with disk-like compartments

    Science.gov (United States)

    Yu, Xiaolei; Zhang, Cancan; You, Sujian; Liu, Huiqin; Zhang, Lingling; Liu, Wei; Guo, Shi-Shang; Zhao, Xing-Zhong

    2016-02-01

    Aiming to synthesize multiferroic materials in microscale, a microfluidic device capable of generating multiferroic Janus microparticles is demonstrated. Through bonding two polydimethylsiloxane (PDMS) layers "face to face," laminar flow containing an upper layer and a lower layer can be realized. Accordingly, poly(vinylidene fluoride-trifluoroethylene) ferroelectric polymers and Fe3O4 ferromagnetic particles are separately encapsulated in the two layers of a single droplet. Numerical simulation enables the analysis of cross-mixing between the two counterparts and helps to find an optimized location for adding subsequent ultraviolet treatment, which will polymerize the droplets into Janus particles without any side effect. By modulation of the flow rate, the size of the Janus particles can be precisely tuned. Finally, the ferroelectricity and magnetism of the Janus particles are verified by the magnetization and polarization measurements, indicating the multiferroic nature.

  20. Combining intra- and intermolecular charge-transfer: a new strategy towards molecular ferromagnets and multiferroics.

    Science.gov (United States)

    Di Maiolo, Francesco; Sissa, Cristina; Painelli, Anna

    2016-01-21

    Organic ferroelectric materials are currently a hot research topic, with mixed stack charge transfer crystals playing a prominent role with their large, electronic-in-origin polarization and the possibility to tune the transition temperature down to the quantum limit and/or to drive the ferroelectric transition via an optical stimulus. By contrast, and in spite of an impressive research effort, organic ferromagnets are rare and characterized by very low transition temperatures. Coexisting magnetic and electric orders in multiferroics offer the possibility to control magnetic (electric) properties by an applied electric (magnetic) field with impressive technological potential. Only few examples of multiferroics are known today, based on inorganics materials. Here we demonstrate that, by decorating mixed stack charge transfer crystals with organic radicals, a new family of robust molecular ferromagnets can be designed, stable up to ambient temperature, and with a clear tendency towards multiferroic behaviour.

  1. Phonon excitations and magnetoelectric coupling in multiferroic RMn2O5

    Science.gov (United States)

    Golrokh Bahoosh, Safa; Wesselinowa, Julia M.; Trimper, Steffen

    2013-05-01

    Multiferroic rare-earth manganites are theoretically studied by focusing on the coupling to the lattice degrees of freedom. We demonstrate analytically that the phonon excitations in the multiferroic phase are strongly affected by the magnetoelectric coupling, the spin-phonon interaction and the anharmonic phonon-phonon interaction. Based on a microscopic model, the temperature dependence of the phonon dispersion relation is analyzed. It offers an anomaly at both the ferroelectric and the magnetic transition indicating the mutual coupling between multiferroic orders and lattice distortions. Depending on the sign of the spin-phonon coupling the phonon modes become softer or harder in accordance with experimental observations. We show that the phonon spectrum can be also controlled by an external magnetic field. The phonon energy is enhanced by increasing that field. The applied Green's function technique allows the calculation of the macroscopic magnetization depending on both the phonon-phonon and the spin-phonon couplings.

  2. Evidence for room temperature electric polarization in RMn(2)O(5) multiferroics.

    Science.gov (United States)

    Balédent, V; Chattopadhyay, S; Fertey, P; Lepetit, M B; Greenblatt, M; Wanklyn, B; Saouma, F O; Jang, J I; Foury-Leylekian, P

    2015-03-20

    It is established that the multiferroics RMn(2)O(5) crystallize in the centrosymmetric Pbam space group and that the magnetically induced electric polarization appearing at low temperature is accompanied by a symmetry breaking. However, both our present x-ray study-performed on compounds with R=Pr,Nd,Gd,Tb, and Dy-and first-principles calculations unambiguously rule out this picture. Based on structural refinements, geometry optimization, and physical arguments, we demonstrate in this Letter that the actual space group is likely to be Pm. This turns out to be of crucial importance for RMn(2)O(5) multiferroics since Pm is not centrosymmetric. Ferroelectricity is thus already present at room temperature, and its enhancement at low temperature is a spin-enhanced process. This result is also supported by direct observation of optical second harmonic generation. This fundamental result calls into question the actual theoretical approaches that describe the magnetoelectric coupling in this multiferroic family.

  3. 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 ...

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

    Science.gov (United States)

    Chapon, L. C.

    2012-03-01

    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.

  5. 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.

  6. Magnetic and ferroelectric properties of multiferroic RMn2O5

    Science.gov (United States)

    Noda, Y.; Kimura, H.; Fukunaga, M.; Kobayashi, S.; Kagomiya, I.; Kohn, K.

    2008-10-01

    The magnetic and ferroelectric properties of multiferroic RMn2O5 (R = Y, Tb, Ho, Er, Tm) are reviewed based on recent neutron diffraction and dielectric measurements. Successive phase transitions of magnetic and dielectric ordering were found to occur simultaneously in this system. The characteristic magnetic ordering of the system exhibits an incommensurate-commensurate phase transition, and again transitions to an incommensurate phase. Special attention is given to the magnetic structure in order to discuss the mechanism for the introduction of ferroelectric polarization. For all the compounds examined, the spin configuration for Mn4+ and Mn3+ ions in the commensurate magnetic phase, where spontaneous electric polarization occurs, was determined to be a transverse spiral spin structure propagating along the c-axis. By contrast, the alignment of the induced 4f moment of R3+ ions showed variation, depending on the character of each of the elements. Corresponding responses to external fields such as a magnetic field, hydrostatic pressure etc at low temperature are strongly dependent on the rare earth element present in the RMn2O5 system. The so-called colossal magnetoelectric effect in this system can be easily interpreted by the phase transition from the magnetic incommensurate and weak ferroelectric phase to the commensurate and ferroelectric phase.

  7. 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.

  8. 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)

  9. 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.

  10. 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.

  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. 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

  13. Hydrodynamics of domain walls in ferroelectrics and multiferroics: Impact on memory devices

    Science.gov (United States)

    Scott, J. F.; Evans, D. M.; Gregg, J. M.; Gruverman, A.

    2016-07-01

    The standard "Kittel Law" for the thickness and shape of ferroelectric, ferroelastic, or ferromagnet domains assumes mechanical equilibrium. The present paper shows that such domains may be highly nonequilibrium, with unusual thicknesses and shapes. In lead germanate and multiferroic lead zirconate titanate iron tantalate domain wall instabilities resemble hydrodynamics (Richtmyer-Meshkov and Helfrich-Hurault, respectively).

  14. Structural Anomalies and Multiferroic Behavior in Magnetically Frustrated TbMn2O5

    NARCIS (Netherlands)

    Chapon, L.C.; Blake, G.R.; Gutmann, M.J.; Park, S.; Hur, N.; Radaelli, P.G.; Cheong, S-W.

    2004-01-01

    We have studied the magnetostructural phase diagram of multiferroic TbMn2O5 as a function of temperature and magnetic field by neutron diffraction. Dielectric and magnetic anomalies are found to be associated with steps in the magnetic propagation vector, including a rare example of a commensurate-i

  15. Multiferroic BiFeO3 thin films for multifunctional devices.

    Science.gov (United States)

    Singh, Manish K; Yang, Yi; Takoudis, Christos G; Tatarenko, A; Srinivasan, G; Kharel, P; Lawes, G

    2010-09-01

    We report the metalorganic chemical vapor deposition of crystalline BiFeO3 films on platinized silicon substrates using n-butylferrocene, triphenylbismuth and oxygen. Based on thermogravimetric analysis data, the suitability of these two precursors for depositing BiFeO3 is discussed. The deposited films were characterized for structure and morphology using X-ray diffraction and scanning electron microscopy. Composition analysis using X-ray photoelectron spectroscopy revealed that the films were stoichiometric BiFeO3. Electrostatic force microscopy indicated that the film had polarizable domains that showed no deterioration in polarization over time long after electric poling. The film showed a saturation magnetization of 10 +/- 1 emu/cm3 at room temperature.

  16. 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.

  17. Direct observation of multiferroic vortex domains in YMnO3.

    Science.gov (United States)

    Zhang, Qinghua; Tan, Guotai; Gu, Lin; Yao, Yuan; Jin, Changqing; Wang, Yanguo; Duan, Xiaofeng; Yu, Richeng

    2013-01-01

    Topological vortices with swirling ferroelectric, magnetic and structural anti-phase relationship in hexagonal RMnO3 (R = Ho to Lu, Y, and Sc) have attracted much attention because of their intriguing behaviors. Herein, we report the structure of multiferroic vortex domains in YMnO3 at atomic scale using state-of-the-art aberration-corrected scanning transmission electron microscopy (STEM). Two types of displacements were identified among six domain walls (DWs); six translation-ferroelectric domains denoted by α+, γ-, β+, α-, γ+ and β-, respectively, were recognized, demonstrating the interlocking nature of the anti-vortex domain. We found that the anti-vortex core is about four unit cells wide. In addition, we reconstructed the vortex model with three swirling pairs of DWs along the [001] direction. These results are very critical for the understanding of topological behaviors and unusual properties of the multiferroic vortex.

  18. 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.

  19. Chemically modulated multiferroicity in Dy-doped Gd2Ti2O7

    Science.gov (United States)

    Lin, L.; Zhao, Z. Y.; Liu, D.; Xie, Y. L.; Dong, S.; Yan, Z. B.; Liu, J.-M.

    2013-05-01

    The ferroelectricity and magnetoelectric coupling of Gd2Ti2O7 and Gd2-xDyxTi2O7 with Dy3+ substitution of Gd3+ are investigated. For Gd2Ti2O7, a ferroelectric polarization emerges at ˜30 K and is only ˜1.80 μC/m2 at 2 K, while the magnetoelectric response is quite weak. The Dy3+ substitution in Gd2-xDyxTi2O7, however, results in significant enhancement of polarization with remarkable magnetoelectric response up to 35% at 2 K under a magnetic field of 9 T, suggesting the multiferroicity of Gd2-xDyxTi2O7. It is understood that the chemical modulation of the multiferroicity is basically related to the extreme sensitivity of the spin-spin interactions in this highly frustrated system.

  20. 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.

  1. 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)

  2. Lattice dynamics and spin-phonon interactions in multiferroic RMn2O5: Shell model calculations

    Science.gov (United States)

    Litvinchuk, A. P.

    2009-08-01

    The results of the shell model lattice dynamics calculations of multiferroic RMn2O5 materials (space group Pbam) are reported. Theoretical even-parity eigenmode frequencies are compared with those obtained experimentally in polarized Raman scattering experiments for R=Ho,Dy. Analysis of displacement patterns allows to identify vibrational modes which facilitate spin-phonon coupling by modulating the Mn-Mn exchange interaction and provides explanation of the observed anomalous temperature behavior of phonons.

  3. 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...

  4. 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.

  5. 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.

  6. 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

  7. Atomically engineered ferroic layers yield a room-temperature magnetoelectric multiferroic.

    Science.gov (United States)

    Mundy, Julia A; Brooks, Charles M; Holtz, Megan E; Moyer, Jarrett A; Das, Hena; Rébola, Alejandro F; Heron, John T; Clarkson, James D; Disseler, Steven M; Liu, Zhiqi; Farhan, Alan; Held, Rainer; Hovden, Robert; Padgett, Elliot; Mao, Qingyun; Paik, Hanjong; Misra, Rajiv; Kourkoutis, Lena F; Arenholz, Elke; Scholl, Andreas; Borchers, Julie A; Ratcliff, William D; Ramesh, Ramamoorthy; Fennie, Craig J; Schiffer, Peter; Muller, David A; Schlom, Darrell G

    2016-01-01

    Materials that exhibit simultaneous order in their electric and magnetic ground states hold promise for use in next-generation memory devices in which electric fields control magnetism. Such materials are exceedingly rare, however, owing to competing requirements for displacive ferroelectricity and magnetism. Despite the recent identification of several new multiferroic materials and magnetoelectric coupling mechanisms, known single-phase multiferroics remain limited by antiferromagnetic or weak ferromagnetic alignments, by a lack of coupling between the order parameters, or by having properties that emerge only well below room temperature, precluding device applications. Here we present a methodology for constructing single-phase multiferroic materials in which ferroelectricity and strong magnetic ordering are coupled near room temperature. Starting with hexagonal LuFeO3-the geometric ferroelectric with the greatest known planar rumpling-we introduce individual monolayers of FeO during growth to construct formula-unit-thick syntactic layers of ferrimagnetic LuFe2O4 (refs 17, 18) within the LuFeO3 matrix, that is, (LuFeO3)m/(LuFe2O4)1 superlattices. The severe rumpling imposed by the neighbouring LuFeO3 drives the ferrimagnetic LuFe2O4 into a simultaneously ferroelectric state, while also reducing the LuFe2O4 spin frustration. This increases the magnetic transition temperature substantially-from 240 kelvin for LuFe2O4 (ref. 18) to 281 kelvin for (LuFeO3)9/(LuFe2O4)1. Moreover, the ferroelectric order couples to the ferrimagnetism, enabling direct electric-field control of magnetism at 200 kelvin. Our results demonstrate a design methodology for creating higher-temperature magnetoelectric multiferroics by exploiting a combination of geometric frustration, lattice distortions and epitaxial engineering. PMID:27652564

  8. 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

  9. 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

  10. 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.

    2016-08-01

    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.

  11. 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.

  12. 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

  13. 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)

  14. 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.

  15. Electric-field control of electromagnon propagation and spin-wave injection in a spiral multiferroic/ferromagnet composite

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hong-Bo [Institut für Physik, Martin-Luther Universität Halle-Wittenberg, D-06120 Halle (Germany); Zhejiang Institute of Modern Physics and Department of Physics, Zhejiang University, Hangzhou 310027 (China); Li, You-Quan [Zhejiang Institute of Modern Physics and Department of Physics, Zhejiang University, Hangzhou 310027 (China); Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093 (China); Berakdar, Jamal [Institut für Physik, Martin-Luther Universität Halle-Wittenberg, D-06120 Halle (Germany)

    2015-01-28

    We consider theoretically a composite chain consisting of a multiferroic helimagnet coupled to a conventional ferromagnet and inspect the conversion of electromagnon excitation into spin waves and vice versa. We demonstrate an electric-field control of spin-wave injection realized by electrically exciting an electromagnon that propagates with an intrinsic frequency larger than the gap of the spin wave in the ferromagnet. The efficiency of the conversion of the electromagnon into spin waves depends strongly on the strength of the magnetoelectric coupling at the interface and the intrinsic frequency of the multiferroic helimagnets. The phenomena predicted here suggest that a multiferroic/ferromagnet composite offers new opportunities for spin-wave injection, conversion, and control using electric field.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. A Local Approach to Solid State Problems: Pseudo Jahn-Teller origin of Ferroelectricity and Multiferroicity

    Science.gov (United States)

    Bersuker, I. B.

    2013-04-01

    This is a partially review paper in which, in continuation of previous work, it is shown that in perovskite crystals of ABO3 type the spontaneous polarization is triggered by local vibronic interactions, the pseudo Jahn-Teller effect (PJTE). The driving force of the latter is added covalency by distortion, which is essentially of local (chemical) origin. The local origin of polar instability in crystals is confirmed by the theorem of structural instability proved earlier. For crystals of BaTiO3 type local PJT interactions of the metal ion with the oxygen environment results in a peculiar adiabatic potential energy surface (APES) which has eight trigonal [111] type minima, twelve [110] type saddle points between them, six higher in energy [100] type saddle points at the top of the barrier connecting four minima, and a maximum at the cubic symmetry. The temperature dependence of the free energy with this potential explains the origin of all the four phases in such crystals; only the lowest rhombohedral phase is fully ordered, the other two ones at higher temperatures are partially disordered, and the paraelectric phase is fully (three-dimensionally) disordered. For BaTiO3 this picture is confirmed by numerical estimates and ab initio DFT calculations. An important further development of this theory was reached recently by showing that not only B ions with electronic d0 configurations are subject to the PJTE instability to produce ferroelectricity in perovskite crystals ("the d0 mystery"), but some other specific dn configurations with unpaired electrons may be dipolar active too, the crystal being thus both magnetic and ferroelectric (multiferroic), and the necessary conditions for such multiferroicity are formulated for the whole d0-dn variety of perovskites. Moreover, the condition of multiferroicity was shown to depend also on the spin state, high-spin or low-spin, which in conditions of spin crossover leads to a magnetic-ferroelectric crossover that can be

  1. 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

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

    Directory of Open Access Journals (Sweden)

    Gollapudi Sreenivasulu

    2016-02-01

    Full Text Available 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.

  3. 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

    2016-02-20

    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.

  4. 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

  5. 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...

  6. 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

  7. Electronic Correlations Decimate the Ferroelectric Polarization of Multiferroic HoMn2O5

    Science.gov (United States)

    Giovannetti, Gianluca; van den Brink, Jeroen

    2008-06-01

    We show that electronic correlations decimate the intrinsic ferroelectric polarization of multiferroic manganites RMn2O5, where R is a rare earth element. Such is manifest from ab initio band structure computations that account for the Coulomb interactions between the manganese 3d electrons—the root of magnetism in RMn2O5. Including these leads to an amplitude and direction of polarization of HoMn2O5 that agree with experiment. The decimation is caused by a near cancellation of the ionic polarization induced by the lattice and the electronic one due to valence charge redistributions.

  8. Fast 180° magnetization switching in a strain-mediated multiferroic heterostructure driven by a voltage

    Science.gov (United States)

    Peng, Ren-Ci; Hu, Jia-Mian; Momeni, Kasra; Wang, Jian-Jun; Chen, Long-Qing; Nan, Ce-Wen

    2016-06-01

    Voltage-driven 180° magnetization switching provides a low-power alternative to current-driven magnetization switching widely used in spintronic devices. Here we computationally demonstrate a promising route to achieve voltage-driven in-plane 180° magnetization switching in a strain-mediated multiferroic heterostructure (e.g., a heterostructure consisting of an amorphous, slightly elliptical Co40Fe40B20 nanomagnet on top of a Pb(Zr,Ti)O3 film as an example). This 180° switching follows a unique precessional path all in the film plane, and is enabled by manipulating magnetization dynamics with fast, local piezostrains (rise/release time spintronics.

  9. 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 ...

  10. Magnetoelectric coupling in multiferroic BaTiO3-CoFe2O4 composite nanofibers via electrospinning

    Science.gov (United States)

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

    2015-07-01

    Magnetoelectric (ME) coupling in Pb-based multiferroic composites has been widely investigated due to the excellent piezoelectric property of lead zirconate titanate (PZT). In this letter, we report a strategy to create a hybrid Pb-free ferroelectric and ferromagnetic material and detect its ME coupling at the nanoscale. Hybrid Pb-free multiferroic BaTiO3-CoFe2O4 (BTO-CFO) composite nanofibers (NFs) were generated by sol-gel electrospinning. The perovskite structure of BTO and the spinel structure of CFO nanograins were homogenously distributed in the composite NFs and verified by bright-field transmission electron microscopy observations along the perovskite [111] zone axis. Multiferroicity was confirmed by amplitude-voltage butterfly curves and magnetic hysteresis loops. ME coupling was observed in terms of a singularity on a dM/dT curve at the ferroelectric Curie temperature (TC) of BaTiO3. The lateral ME coefficient was investigated by the evolution of the piezoresponse under an external magnetic field of 1000 Oe and was estimated to be α31 =0.78× 104 \\text{mV cm}-1 \\text{Oe}-1 . These findings could enable the creation of nanoscale Pb-free multiferroic composite devices.

  11. Enhanced magnetodielectric and multiferroic properties of Er-doped bismuth ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, A.; Banerjee, M. [Department of Physics, National Institute of Technology, Durgapur 713209 (India); Basu, S., E-mail: soumen.basu@phy.nitdgp.ac.in [Department of Physics, National Institute of Technology, Durgapur 713209 (India); Mukadam, M.D.; Yusuf, S.M. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Pal, M. [CSIR-Central Glass & Ceramic Research Institute, Kolkata 700032 (India)

    2015-07-15

    An enhancement in multiferroic properties has been achieved for chemically prepared BFO nanoparticles by doping with erbium (Er). XRD along with electron microscopy study reveals the phase purity and nanocrystalline nature of BFO. Enhancement of both the magnetic moment and resistivity is observed by virtue of Er doping. The observed enhanced magnetic moment is considered to be associated with smaller crystallite whereas increase of resistivity may be attributed to a decrease of oxygen vacancies. Doping also display an improvement of leakage behaviour and dielectric constant in nanocrystalline BFO, reflected in well-developed P-E loop. In addition, large enhancement in magnetodielectric coefficient is observed because of Er doping. Therefore, the results provide interesting approaches to improve the multiferroic properties of BFO, which has great implication towards its applications. - Highlights: • Synthesis of pure Er-doped BFO nanoparticles by chemical route. • Large increase in magnetic moment and resistivity due to Er doping. • Er doping produce well developed P-E loop and enhance polarization. • Drastic increase in dielectric constant as well as magnetodielectric coefficient observes because of Er doping.

  12. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Charnaya, E.V., E-mail: charnaya@live.com [Department of Physics, National Cheng Kung University, Tainan 701, Taiwan (China); Institute of Physics, St. Petersburg State University, Petrodvorets, St. Petersburg 198904 (Russian Federation); Lee, M.K. [Department of Physics, National Cheng Kung University, Tainan 701, Taiwan (China); Tien, C. [Department of Physics, National Cheng Kung University, Tainan 701, Taiwan (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701 Taiwan (China); Pak, V.N.; Formus, D.V. [Herzen State Pedagogical University of Russia, 6 Kazanskaya, St. Petersburg 191186 (Russian Federation); Pirozerskii, A.L.; Nedbai, A.I. [Institute of Physics, St. Petersburg State University, Petrodvorets, St. Petersburg 198904 (Russian Federation); Ubyivovk, E.V. [Interdisciplinary Resource Center for Nanotechnology, St. Petersburg State University, Petrodvorets, St. Petersburg 198904 (Russian Federation); Baryshnikov, S.V. [Blagoveschensk State Pedagogical University, Blagoveschensk, 675002 (Russian Federation); Chang, L.J. [Department of Physics, National Cheng Kung University, Tainan 701, Taiwan (China)

    2012-09-15

    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: Black-Right-Pointing-Pointer CuO nanoparticles embedded into porous glass compared to bulk. Black-Right-Pointing-Pointer ZFC and FC magnetizations bifurcate in the nanocomposite and bulk CuO. Black-Right-Pointing-Pointer Dc magnetization suggests a reduction of the temperature T{sub N1} till about 190 K. Black-Right-Pointing-Pointer Temperature T{sub N2} of the transition into multiferroic phase did not change.

  14. Pronounced multiferroicity in oleic acid stabilized BiFeO3 nanocrystals at room temperature.

    Science.gov (United States)

    Mahesh, Dabbugalla; Mandal, Swapan K; Mahato, Bipul K; Rana, Bivas; Barman, Anjan

    2013-06-01

    We report on the experimental observation of pronounced multiferroicity in BiFeO3 nanocrystals (size approximately 40 nm) at room temperature. Large scale BiFeO3 nanocrystals are synthesized using a low temperature chemical route and further stabilized with oleic acid. The nanocrystals exhibit a significant distortion in lattice parameter c compared to the bulk. Oleic acid plays an important role in reducing oxygen vacancies and Fe2+ ions at the nanocrystal surface giving rise to a high resistivity (approximately 10(10) omega-cm at 300 K) of the sample. The direct band gap of nanocrystals is measured to be approximately 4.2 eV (about 1.5 times the bulk value) suggesting a strong quantum confinement effect. The nanocrystals show a remarkably high spontaneous saturation magnetization approximately 4.39 emu/g along with a prominent ferroelectric hysteresis loop at room temperature. Particle size effect leading to the appearance of large number of uncompensated spins and suppression of modulated spin structure have resulted a strong spontaneous magnetization in such nanoscale multiferroic materials. PMID:23862453

  15. Tunneling magnetoresistance and electroresistance in Fe/PbTiO3/Fe multiferroic tunnel junctions

    Science.gov (United States)

    Dai, Jian-Qing

    2016-08-01

    We perform first-principles electronic structure and spin-dependent transport calculations for a Fe/PbTiO3/Fe multiferroic tunnel junction with asymmetric TiO2- and PbO-terminated interfaces. We demonstrate that the interfacial electronic reconstruction driven by the in situ screening of ferroelectric polarization, in conjunction with the intricate complex band structure of barrier, play a decisive role in controlling the spin-dependent tunneling. Reversal of ferroelectric polarization results in a transition from insulating to half-metal-like conducting state for the interfacial Pb 6pz orbitals, which acts as an atomic-scale spin-valve by releasing the tunneling current in antiparallel magnetization configuration as the ferroelectric polarization pointing to the PbO-terminated interface. This effect produces large change in tunneling conductance. Our results open an attractive avenue in designing multiferroic tunnel junctions with excellent performance by exploiting the interfacial electronic reconstruction originated from the in situ screening of ferroelectric polarization.

  16. 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.

  17. 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.

  18. Single-domain multiferroic BiFeO3 films

    Science.gov (United States)

    Kuo, C.-Y.; Hu, Z.; Yang, J. C.; Liao, S.-C.; Huang, Y. L.; Vasudevan, R. K.; Okatan, M. B.; Jesse, S.; Kalinin, S. V.; Li, L.; Liu, H. J.; Lai, C.-H.; Pi, T. W.; Agrestini, S.; Chen, K.; Ohresser, P.; Tanaka, A.; Tjeng, L. H.; Chu, Y. H.

    2016-09-01

    The strong coupling between antiferromagnetism and ferroelectricity at room temperature found in BiFeO3 generates high expectations for the design and development of technological devices with novel functionalities. However, the multi-domain nature of the material tends to nullify the properties of interest and complicates the thorough understanding of the mechanisms that are responsible for those properties. Here we report the realization of a BiFeO3 material in thin film form with single-domain behaviour in both its magnetism and ferroelectricity: the entire film shows its antiferromagnetic axis aligned along the crystallographic b axis and its ferroelectric polarization along the c axis. With this we are able to reveal that the canted ferromagnetic moment due to the Dzyaloshinskii-Moriya interaction is parallel to the a axis. Furthermore, by fabricating a Co/BiFeO3 heterostructure, we demonstrate that the ferromagnetic moment of the Co film does couple directly to the canted moment of BiFeO3.

  19. 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.

  20. 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.

  1. 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.

  2. A study of the dielectric and magnetic properties of multiferroic materials using the Monte Carlo method

    Directory of Open Access Journals (Sweden)

    A. Sosa

    2012-03-01

    Full Text Available A study of the dielectric and magnetic properties of multiferroic materials using the Monte Carlo (MC method is presented. Two different systems are considered: the first, ferroelectric-antiferromagnetic (FE-AFM recently studied by X. S. Gaoand J. M. Liu and the second antiferroelectric-ferromagnetic (AFE-FM. Based on the DIFFOUR-Ising hybrid microscopic model developed by Janssen, a Hamiltonian that takes into account the magnetoelectric coupling in both ferroic phases is proposed. The obtained results show that the existence of such coupling modifies the ferroelectric and magnetic ordering in both phases. Additionally, it is shown that the presence of a magnetic or an electric field influences the electric polarization and the magnetization, respectively, making evident the magnetoelectric effect.

  3. Spiral Spin Structure in the Commensurate Magnetic Phase of Multiferroic RMn2O5

    Science.gov (United States)

    Kimura, Hiroyuki; Kobayashi, Satoru; Fukuda, Yoshikazu; Osawa, Toshihiro; Kamada, Youichi; Noda, Yukio; Kagomiya, Isao; Kohn, Kay

    2007-07-01

    Crystal and magnetic structure analyses have been performed for single crystals of multiferroic materials RMn2O5 (R = Y, Ho, Er) using the neutron diffraction technique. For all the compounds, the magnetic structure in the commensurate magnetic phase, where spontaneous electric polarization occurs, was determined to be a transverse spiral spin structure propagating along the c-axis. The results demonstrate that the spin configuration for Mn4+ and Mn3+ ions is essentially the same in all three materials, suggesting that the ferroelectricity of the commensurate magnetic phase originates from the spin configurations of Mn ions. By contrast, the alignment of the induced 4 f-moment of Ho3+ ions is quite different from that of Er3+ ions, which might give a rich variety of magnetic field response for magnetic and dielectric properties in the RMn2O5 system.

  4. Measurement of complicated temperature-dependent polarization of multiferroic RMn2O5

    Science.gov (United States)

    Fukunaga, Mamoru; Noda, Yukio

    2011-09-01

    We have measured the temperature-dependent electric polarization P(T) of multiferroic rare-earth (R) manganese oxides RMn2O5 using both typical pyroelectric measurements and hysteresis loops with the double-wave method (DWM), and revealed the complicated behavior of the P(T). RMn2O5 single crystal samples often exhibit a tendency to macroscopically polarize without applying an external electric field. We have found that the tendency appeared in P(T) by the pyroelectric measurement can be measured by the DWM loops. The tendency to polarize is equivalent to asymmetric non-hystersis loops obtained by the DWM. We clarify the relationship between P(T) by pyroelectric measurement and that by the DWM loops, which can warrant the measured P(T).

  5. Magnetic domains in multiferroic YMn$2O5 probed by Spherical Neutron Polarimetry under electric field

    Science.gov (United States)

    Vecchini, Carlo; Chapon, Laurent; Radaelli, Paolo; Daoud-Aladine, Aziz; Brown, Jane; Chatterji, Tapan; Park, Soonyong; Cheong, Sang-Wook

    2008-03-01

    Precise determination of the magnetic structures in multiferroics RMn2O5 (R: Y, Ho, Bi) have been obtained by single crystal neutron diffraction. The analysis shows the presence of zig-zag antiferromagnetic chains in the ab-plane. An additional weak magnetic component parallel to the c-axis was detected which is modulated in phase quadrature with the a-b components. The nature and population of the coexisting antiferromagnetic domains in YMn2O5 have been determined by Spherical Neutron Polarimetry under an external electric field. We have proved that reversing the electrical polarity results in the inversion of the population of two types of antiferromagnetic domains, with opposite in-plane spin components. This analysis strongly supports theories in which the coupling of the magnetic configuration to the ferroelectric polarisation is due to magnetic exchange striction and likely not related to the small cycloidal modulation in the bc-plane.

  6. Spin chirality and electric polarization in multiferroic compounds RMn2O5 ( R=Ho, Er)

    Science.gov (United States)

    Wakimoto, Shuichi; Kimura, Hiroyuki; Fukunaga, Mamoru; Nishihata, Keisuke; Takeda, Masayasu; Kakurai, Kazuhisa; Noda, Yukio; Tokura, Yoshinori

    2009-09-01

    Polarized neutron diffraction experiments have been performed on multiferroic materials RMn2O5 ( R=Ho, Er) under electric fields in the ferroelectric commensurate (CM) and the low-temperature incommensurate (LT-ICM) phases, where the former has the highest electric polarization and the latter has reduced polarization. It is found that, after cooling in electric fields down to the CM phase, the magnetic chirality is proportional to the electric polarization. Also we confirmed that the magnetic chirality can be switched by the polarity of the electric polarization in both the CM and LT-ICM phases. These facts suggest an intimate coupling between the magnetic chirality and the electric polarization. However, upon the transition from the CM to LT-ICM phase, the reduction of the electric polarization is not accompanied by any reduction of the magnetic chirality, implying that the CM and LT-ICM phases contain different mechanisms of the magnetoelectric coupling.

  7. An effective model of magnetoelectricity in multiferroics RMn2O5

    Science.gov (United States)

    Fang, Chen; Hu, Jiangping

    2008-06-01

    An effective model is developed to explain the phase diagram and the mechanism of magnetoelectric coupling in multiferroics, RMn2O5. We show that the nature of magnetoelectric coupling in RMn2O5 is a coupling between two Ising-type orders, namely, the ferroelectric order in the b-axis, and the.coupled magnetic order between two frustrated antiferromagnetic chains. The frustrated magnetic structure drives the system to a commensurate-incommensurate phase transition, which can be understood as a competition between a collinear order stemming from the "order by disorder" mechanism and a chiral symmetry order. The low-energy excitation is calculated and it quantitatively matches experimental results. Distinct features and the effects of external magnetic field in the electromagnon spectra in the incommensurate phase are predicted.

  8. Electromagnons in multiferroic RMn2O5 compounds and their microscopic origin

    Science.gov (United States)

    Sushkov, A. B.; Mostovoy, M.; Valdés Aguilar, R.; Cheong, S.-W.; Drew, H. D.

    2008-10-01

    We summarize the existing experimental data on electromagnons in multiferroic RMn2O5 compounds, where R denotes a rare earth ion, Y or Bi, and discuss a realistic microscopic model of these materials based on the assumption that the microscopic mechanism of magnetically induced ferroelectricity and electromagnon absorption relies entirely on the isotropic Heisenberg exchange and magnetostrictive coupling of spins to a polar lattice mode and does not involve relativistic effects. This model explains many magnetic and optical properties of RMn2O5 manganites, such as the spin re-orientation transition, magnetically induced polarization, appearance of the electromagnon peak in the non-collinear spin state and the polarization of light for which this peak is observed. We compare experimental and theoretical results on electromagnons in RMn2O5 and RMnO3 compounds.

  9. 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)

  10. Spin-state crossover in multiferroic Ca3Co2-xMnxO6

    Science.gov (United States)

    Flint, R.; Yi, H.-T.; Chandra, P.; Cheong, S.-W.; Kiryukhin, V.

    2010-03-01

    Ca3Co2-xMnxO6 (x˜0.96) is a multiferroic with spin-chains of alternating Co2+ and Mn4+ ions. The spin state of Co2+ remains unresolved due to a discrepancy between high-temperature x-ray absorption (S=(3)/(2)) and low-temperature neutron (S=(1)/(2)) measurements. Using a combination of magnetic modeling and crystal-field analysis, we show that the existing low temperature data cannot be reconciled within a high spin scenario by invoking spin-orbit or Jahn-Teller distortions. To unify the experimental results, we propose a spin-state crossover with specific experimental predictions.

  11. Electric field control of magnon-induced magnetization dynamics in multiferroics.

    Science.gov (United States)

    Risinggård, Vetle; Kulagina, Iryna; Linder, Jacob

    2016-01-01

    We consider theoretically the effect of an inhomogeneous magnetoelectric coupling on the magnon-induced dynamics of a ferromagnet. The magnon-mediated magnetoelectric torque affects both the homogeneous magnetization and magnon-driven domain wall motion. In the domains, we predict a reorientation of the magnetization, controllable by the applied electric field, which is almost an order of magnitude larger than that observed in other physical systems via the same mechanism. The applied electric field can also be used to tune the domain wall speed and direction of motion in a linear fashion, producing domain wall velocities several times the zero field velocity. These results show that multiferroic systems offer a promising arena to achieve low-dissipation magnetization rotation and domain wall motion by exciting spin-waves. PMID:27554064

  12. 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.

  13. 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.

  14. Electric field control of magnon-induced magnetization dynamics in multiferroics

    Science.gov (United States)

    Risinggård, Vetle; Kulagina, Iryna; Linder, Jacob

    2016-08-01

    We consider theoretically the effect of an inhomogeneous magnetoelectric coupling on the magnon-induced dynamics of a ferromagnet. The magnon-mediated magnetoelectric torque affects both the homogeneous magnetization and magnon-driven domain wall motion. In the domains, we predict a reorientation of the magnetization, controllable by the applied electric field, which is almost an order of magnitude larger than that observed in other physical systems via the same mechanism. The applied electric field can also be used to tune the domain wall speed and direction of motion in a linear fashion, producing domain wall velocities several times the zero field velocity. These results show that multiferroic systems offer a promising arena to achieve low-dissipation magnetization rotation and domain wall motion by exciting spin-waves.

  15. Electric field control of magnon-induced magnetization dynamics in multiferroics

    Science.gov (United States)

    Risinggård, Vetle; Kulagina, Iryna; Linder, Jacob

    2016-01-01

    We consider theoretically the effect of an inhomogeneous magnetoelectric coupling on the magnon-induced dynamics of a ferromagnet. The magnon-mediated magnetoelectric torque affects both the homogeneous magnetization and magnon-driven domain wall motion. In the domains, we predict a reorientation of the magnetization, controllable by the applied electric field, which is almost an order of magnitude larger than that observed in other physical systems via the same mechanism. The applied electric field can also be used to tune the domain wall speed and direction of motion in a linear fashion, producing domain wall velocities several times the zero field velocity. These results show that multiferroic systems offer a promising arena to achieve low-dissipation magnetization rotation and domain wall motion by exciting spin-waves. PMID:27554064

  16. 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.

  17. Magnetoelectric coupling effect in transition metal modified polycrystalline BiFeO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sreenivas Puli, Venkata, E-mail: pvsri123@gmail.com [Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70118 (United States); Department of Physics and Institute of Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00936 (United States); Kumar Pradhan, Dhiren [Department of Physics and Institute of Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00936 (United States); Gollapudi, Sreenivasulu [Department of Physics, Oakland University, Rochester, MI 48309-4401 (United States); Coondoo, Indrani [Department of Materials and Ceramic and CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Panwar, Neeraj [Department of Physics, Central University of Rajasthan, Bandar Sindri, Kishangarh 305801, Rajasthan (India); Adireddy, Shiva; Chrisey, Douglas B. [Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70118 (United States); Katiyar, Ram S. [Department of Physics and Institute of Functional Nanomaterials, University of Puerto Rico, San Juan, PR 00936 (United States)

    2014-11-15

    Rare-earth (Sm) and transition metal (Co) modified polycrystalline BiFeO{sub 3} (BFO) thin films have been deposited on Pt/TiO{sub 2}/SiO{sub 2}/Si substrate successfully through pulsed laser deposition (PLD) technique. Piezoelectric, leakage current and temperature dependent dielectric and magnetic behaviour were investigated for the films. Typical “butterfly-shaped” loop were observed in BSFCO films with an effective piezoelectric constant (d{sub 33}) ∼94 pm/V at 0.6 MV/cm. High dielectric constant ∼900 and low dielectric loss ∼0.25 were observed at room temperature. M–H loops have shown relatively high saturation magnetization ∼35 emu/cm{sup 3} at a maximum field of H ∼20 kOe. Enhanced magnetoelectric coupling response is observed under applied magnetic field. The multiferroic, piezoelectric, leakage current behaviours were explored. Such studies should be helpful in designing multiferroic materials based on BSFCO films. - Highlights: • Transition metal modified polycrystalline BiFeO{sub 3} thin films prepared using PLD. • High ME-coupling response was observed in co-substituted BiFeO{sub 3} thin films. • High magnetization ∼35 emu/cm{sup 3} at a maximum field of H ∼20 kOe. • Low leakage current might be due to co-substitution in BiFeO{sub 3} thin films. • A notable piezoelectric constant d{sub 33} ∼94 pm/V was found in BiFeO{sub 3} thin films.

  18. 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.

  19. 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

  20. 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

  1. Hyperfine and crystal field interactions in multiferroic HoCrO3

    Science.gov (United States)

    Kumar, C. M. N.; Xiao, Y.; Nair, H. S.; Voigt, J.; Schmitz, B.; Chatterji, T.; Jalarvo, N. H.; Brückel, Th

    2016-11-01

    We report a comprehensive specific heat and inelastic neutron scattering study to explore the possible origin of multiferroicity in HoCrO3. We have performed specific heat measurements in the temperature range 100 mK-290 K and inelastic neutron scattering measurements were performed in the temperature range 1.5-200 K. From the specific heat data we determined hyperfine splitting at 22.5(2) μeV and crystal field transitions at 1.379(5) meV, 10.37(4) meV, 15.49(9) meV and 23.44(9) meV, indicating the existence of strong hyperfine and crystal field interactions in HoCrO3. Further, an effective hyperfine field is determined to be 600(3) T. The quasielastic scattering observed in the inelastic scattering data and a large linear term γ =6.3(8) mJ mol-1  K-2 in the specific heat is attributed to the presence of short range exchange interactions, which is understood to be contributing to the observed ferroelectricity. Further the nuclear and magnetic entropies were computed to be, ˜17.2 Jmol-1 K-1 and  ˜34 Jmol-1 K-1, respectively. The entropy values are in excellent agreement with the limiting theoretical values. An anomaly is observed in the peak position of the temperature dependent crystal field spectra around 60 K, at the same temperature an anomaly in the pyroelectric current is reported. From this we could elucidate a direct correlation between the crystal electric field excitations of Ho3+ and ferroelectricity in HoCrO3. Our present study, along with recent reports, confirm that HoCrO3, and RCrO3 (R  =  rare earth) in general, possess more than one driving force for the ferroelectricity and multiferroicity.

  2. 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.

  3. Exchange-striction induced giant ferroelectric polarization in copper-based multiferroic material α -Cu2V2O7

    Science.gov (United States)

    Sannigrahi, J.; Bhowal, S.; Giri, S.; Majumdar, S.; Dasgupta, I.

    2015-06-01

    We report α -Cu2V2O7 to be an improper multiferroic with the simultaneous development of electric polarization and magnetization below TC=35 K . The observed spontaneous polarization of 0.55 μ C cm-2 magnitude is highest among copper-based improper multiferroic materials. Our study demonstrates a sizable amount of magnetoelectric coupling below TC, even with a low magnetic field. The theoretical calculations based on density functional theory indicate magnetism in α -Cu2V2O7 is a consequence of ferro-orbital ordering driven by a polar lattice distortion due to the unique pyramidal (CuO5) environment of Cu. Spin-orbit coupling further stabilizes orbital ordering and is crucial for magnetism. The calculations indicate that the origin of the giant ferroelectric polarization is primarily due to the symmetric exchange-striction mechanism and is corroborated by temperature-dependent x-ray studies.

  4. 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.

  5. 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.

  6. 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.

  7. 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)

  8. 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...

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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...

  15. 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.

  16. 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...

  17. 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...

  18. 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

  19. 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.

  20. Understanding the multiferroicity in TmMn2O5 by a magnetically induced ferrielectric model

    Science.gov (United States)

    Yang, L.; Li, X.; Liu, M. F.; Li, P. L.; Yan, Z. B.; Zeng, M.; Qin, M. H.; Gao, X. S.; Liu, J.-M.

    2016-01-01

    The magnetically induced electric polarization behaviors in multiferroic TmMn2O5 in response to varying temperature and magnetic field are carefully investigated by means of a series of characterizations including the high precision pyroelectric current technique. Here polycrystalline rather than single crystal samples are used for avoiding the strong electrically self-polarized effect in single crystals, and various parallel experiments on excluding the thermally excited current contributions are performed. The temperature-dependent electric polarization flop as a major character is identified for different measuring paths. The magneto-current measurements indicate that the electric polarization in the low temperature magnetic phase region has different origin from that in the high temperature magnetic phase. It is suggested that the electric polarization does have multiple components which align along different orientations, including the Mn3+-Mn4+-Mn3+ exchange striction induced polarization PMM, the Tm3+-Mn4+-Tm3+ exchange striction induced polarization PTM, and the low temperature polarization PLT probably associated with the Tm3+ commensurate phase. The observed electric polarization flop can be reasonably explained by the ferrielectric model proposed earlier for DyMn2O5, where PMM and PTM are the two antiparallel components both along the b-axis and PLT may align along the a-axis. Finally, several issues on the unusual temperature dependence of ferroelectric polarizations are discussed. PMID:27713482

  1. 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.

  2. 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

  3. 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.

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

    Science.gov (United States)

    Bahoosh, Safa Golrokh; Wesselinowa, Julia M.; Trimper, Steffen

    2015-08-01

    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.

  5. Magnetic structure and physical properties of the multiferroic compound PrMn2O5

    Science.gov (United States)

    Doubrovsky, C.; André, G.; Bouquet, F.; Elkaim, E.; Li, M.; Greenblatt, M.; Foury-Leylekian, P.

    2012-06-01

    RMn2O5 (R=lanthanide, Bi, Y) multiferroic compounds are intensively studied for their potential application in the spintronic field. In these systems, the key issue is to understand the origin of the strong coupling between the ferroelectric and magnetic orders and to investigate the influence of the nature of the R ions in this coupling. While the phase diagram of RMn2O5 compounds with small R size is well established, this of large R size compounds is missing due to the lack of samples originating with difficulties of synthesis. We present in this paper the first investigation of the thermodynamic, structural and magnetic properties of high quality polycrystalline PrMn2O5 samples. Our work shows that PrMn2O5 presents two magnetic transitions corresponding to commensurate magnetic orderings. We also evidence a weak lattice effect coupled to the magnetic order. Our results point out that the physical properties of PrMn2O5 differ from those of the parent compounds with magnetic R ions.

  6. Local structure studies of multiferroic RMn2O5 (R=Bi, Pr, Gd)

    Science.gov (United States)

    Fabbris, G.; Massa, N. E.; Granado, E.; Maciel, G. A.; Souza, J. A.; Alonso, J. A.; Martinez, M. J.; Azevedo, G. M.

    2009-03-01

    EXAFS measurements from 20 K to 300K were used to investigate the local structure of multiferroic RMn2O5 (R = Bi, Pr, Gd, TM TC 40K) in transmission mode at the Mn K- and R L3- edges in the XAFS2-LNLS beamline and analyzed using the IFEFFIT and FEFF codes. For BiMn2O5, Mn K-edge reveals very small temperature dependence of the Debye-Waller factor (DWF) and an Einstein temperature (ET) from Mn-O bonds of 675±22 K, suggesting that MnO polyhedra are rigid. We find structural distortions in the first coordination shell at the Bi L3-edge associated to vibrational anomalies in the Bi-O bonds. The quantitative analysis relates the origin of such distortions to two very distinct values of DWT and ET (294±7K and 462±28K) for these bonds on first shell. Similar behavior is observed for PrMn2O5, and GdMn2O5.

  7. Pressure effect on ferroelectric properties of multiferroics RMn2O5, (R = Gd, Tm)

    Science.gov (United States)

    Poudel, Narayan; Gooch, Melissa; Lorenz, Bernd; Chu, Ching-Wu; Kim, Jaewook; Cheong, Sang-Wook

    The pressure effect on the ferroelectric properties of the multiferroics GdMn2O5 and TmMn2O5 is studied up to 18.2 kbar. Unlike in RMn2O5 (R= Tb, Ho, Y), no significant change in polarization is observed in TmMn2O5 up to 16.6 kbar . However, a new ferroelectric phase is observed in GdMn2O5 above a critical pressure, Pc = 10 kbar at higher temperature. Our result indicates that pressure decouples the Gd moment from the Mn spin system and splits the ferroelectric phase. Thermal expansion data shows a large increase of the c axis at the ambient-pressure ferroelectric transition. The pressure-induced contraction of the c lattice parameter is found to be the cause for splitting of ferroelectric phase by decoupling of two spin systems above Pc. The pressure-temperature phase diagram is derived based on dielectric and ferroelectric properties.

  8. Nature of unusual spontaneous and field-induced phase transitions in multiferroics RMn 2O 5

    Science.gov (United States)

    Pyatakov, A. P.; Kadomtseva, A. M.; Vorob'ev, G. P.; Popov, Yu. F.; Krotov, S. S.; Zvezdin, A. K.; Lukina, M. M.

    2009-04-01

    Complex magnetic, magnetoelectric and magnetoelastic studies of spontaneous and field-induced phase transitions in TmMn 2O 5 were carried out. In the vicinity of spontaneous phase transition temperatures (35 and 25 K) the magnetoelectric and magnetoelastic dependences demonstrated the jumps of polarization and magnetostriction induced by the field ˜150 kOe. These anomalies can be attributed to the influence of magnetic field on the conditions of incommensurate-commensurate phase transition at 35 K and the reverse one at 25 K. In b-axis dependences the magnetic field-induced spin-reorientation phase transition was also observed below 20 K. Finally the magnetoelectric anomaly associated with metamagnetic transition is observed below the temperature of rare-earth subsystem ordering at relatively small critical fields of 5 kOe. This variety of spontaneous and induced phase transitions in RMn 2O 5 stems from the interplay of three magnetic subsystems: Mn 3+, Mn 4+, R 3+. The comparison with YMn 2O 5 highlights the role of rare earth in low-temperature region (metamagnetic and spin-reorientation phase transitions), while the phase transition at higher temperatures between incommensurate and commensurate phases should be ascribed to the different temperature dependences of Mn 3+ and Mn 4+ ions. The strong correlation of magnetoelastic and magnetoelectric properties observed in the whole class of RMn 2O 5 highlights their multiferroic nature.

  9. Magnetic structure and electric field effects in multiferroic YMn2O5

    Science.gov (United States)

    de Souza, R. A.; Staub, U.; Scagnoli, V.; Garganourakis, M.; Bodenthin, Y.; Huang, S.-W.; García-Fernández, M.; Ji, S.; Lee, S.-H.; Park, S.; Cheong, S.-W.

    2011-09-01

    The magnetic structure of multiferroic RMn2O5 (R = Y, Er) has been investigated by means of resonant soft x-ray diffraction. Energy, temperature, and azimuthal angle scans were performed in addition to reciprocal space maps on the magnetic reflection in the different magnetic phases of YMn2O5. We also investigated the orbital magnetic moment at the oxygen K-edge for RMn2O5 with both, R = Y and R = Er compositions. These moments reflect the strong hybridization between Mn 3d and oxygen 2p states. Experiments with applied electric fields are additionally presented, showing that the helical component of the magnetic structure in the CM phase of YMn2O5 can be reversed by the application of an electric field. However, the incommensurate magnetic reflection in the high-temperature phase is unaffected. Interestingly, this is observed only in the presence of a small electrical current, indicative of a current-induced/-enhanced switching of magnetic domains.

  10. Thermodynamic and neutron diffraction studies on multiferroic NdMn{sub 2}O{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, S.; Balédent, V.; Auban-Senzier, P.; Pasquier, C.; Doubrovsky, C. [Laboratoire de Physique des Solides, Université Paris-Sud, CNRS-UMR 8502, 91405 Orsay (France); Greenblatt, M. [Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); Foury-Leylekian, P., E-mail: pascale.foury@u-psud.fr [Laboratoire de Physique des Solides, Université Paris-Sud, CNRS-UMR 8502, 91405 Orsay (France)

    2015-03-01

    Magnetically frustrated RMn{sub 2}O{sub 5} oxides have attracted considerable attention in recent years, because most of the members of this family show spin ordering induced dielectric polarization along with strong magneto-electric coupling. Although the true origin of the ferroelectricity is still a matter of debate, it has been observed that the magneto-electric phase diagram can be substantially tuned with the variation of rare earth elements. In this work, we have chosen NdMn{sub 2}O{sub 5} as the compound of our interest since it lies exactly in between the ferroelectric and non-ferroelectric members of this family and also, because there are few investigations performed on RMn{sub 2}O{sub 5} systems with large rare earth atoms . With the combination of heat capacity, magnetic susceptibility, dielectric permittivity, powder X-ray diffraction, and powder neutron diffraction measurements, it has been found that NdMn{sub 2}O{sub 5} undergoes an incommensurate magnetic ordering around 30 K followed by a possible ferroelectric-like transition at ∼26 K. Another lock-in kind of magnetic transition appears when the temperature is decreased to ∼15 K. With further lowering of temperature, an antiferromagnetic ordering, which is presumably associated with the Nd{sup 3+}, is achieved near 4 K. This study thus sheds light on a new compound of the RMn{sub 2}O{sub 5} series presenting different multiferroic properties.

  11. Thermodynamic and neutron diffraction studies on multiferroic NdMn2O5

    Science.gov (United States)

    Chattopadhyay, S.; Balédent, V.; Auban-Senzier, P.; Pasquier, C.; Doubrovsky, C.; Greenblatt, M.; Foury-Leylekian, P.

    2015-03-01

    Magnetically frustrated RMn2O5 oxides have attracted considerable attention in recent years, because most of the members of this family show spin ordering induced dielectric polarization along with strong magneto-electric coupling. Although the true origin of the ferroelectricity is still a matter of debate, it has been observed that the magneto-electric phase diagram can be substantially tuned with the variation of rare earth elements. In this work, we have chosen NdMn2O5 as the compound of our interest since it lies exactly in between the ferroelectric and non-ferroelectric members of this family and also, because there are few investigations performed on RMn2O5 systems with large rare earth atoms . With the combination of heat capacity, magnetic susceptibility, dielectric permittivity, powder X-ray diffraction, and powder neutron diffraction measurements, it has been found that NdMn2O5 undergoes an incommensurate magnetic ordering around 30 K followed by a possible ferroelectric-like transition at ∼26 K. Another lock-in kind of magnetic transition appears when the temperature is decreased to ∼15 K. With further lowering of temperature, an antiferromagnetic ordering, which is presumably associated with the Nd3+, is achieved near 4 K. This study thus sheds light on a new compound of the RMn2O5 series presenting different multiferroic properties.

  12. Spin-driven ferroelectricity in the multiferroic compounds of RMn2O5

    Science.gov (United States)

    Kimura, H.; Noda, Y.; Kohn, K.

    2009-04-01

    Neutron diffraction studies under magnetic field as well as under hydrostatic pressure for microscopic magnetism on multiferroic RMn2O5 ( R=rare-earth, Bi, and Y) are reviewed to discuss about the relevance between the magnetic property and dielectric property in detail. Without any external fields, a series of RMn2O5 shows successive magnetic phase transitions of incommensurate-commensurate-incommensurate as temperature decreases, in which the dielectric phase transitions concomitantly occur. At the lowest temperature phase of HoMn2O5, the magnetic transition from the incommensurate phase to the commensurate one is induced by applying both magnetic field and hydrostatic pressure. At this field-induced magnetic transition, a spontaneous electric polarization simultaneously induced, indicating that the ferroelectricity in this material is magnetically controlled. Competition of multiple magnetic ground states due to intensional magnetic frustration in this system can be easily tuned by applying external fields, which give rise to the rich variety of spin-driven dielectric transitions.

  13. Classification and Interpretation of the Polarization of Multiferroic RMn2O5

    Science.gov (United States)

    Fukunaga, Mamoru; Noda, Yukio

    2010-05-01

    We have collected and compared temperature-dependent polarization data of multiferroic RMn2O5 for 11 kinds of rare earths (R) from the literature and our own measurements. Although the reported data are inconsistent, it was found that the maximum polarization values for R=Y, Dy, Ho, Er, and Tm are almost equal above 30 K except for the phase transition temperature where the polarization disappears. The findings suggest a standard polarization value for RMn2O5 of 100-120 nC/cm2 at 30 K in a commensurate magnetic (CM) phase. We discuss the nature and issues of the measured polarization of RMn2O5 from the data and our detailed measurement results for YMn2O5. Temperature-dependent ferroelectric hysteresis loops of YMn2O5 by the double-wave method reveal that an antiferroelectric-like high-temperature incommensurate magnetic (ICM) phase and a ferroelectric low-temperature ICM phase, while the intermediate CM phase is ferrielectric.

  14. Material Designs and Combinational Growth Techniques to Enable Novel Multiferroic Devices

    Science.gov (United States)

    Cole, Melanie; Ngo, Eric; Ivill, Mathew; Hirsch, S.; Hubbard, Cliff; Toonen, Ryan; Sarney, Wendy; Integrated Electromagnetic Materials Research Group Collaboration

    2013-03-01

    Voltage control of magnetism in magnetic/ferroelectric bilayers has been most recently demonstrated in ultrathin metallic magnetic films through an electric field induced spin polarized charge screening effect. Voltage-controlled magnetism in magnetic/ferroelectric multilayers would provide a unique opportunity for integrating voltage-tunable RF/microwave magnetic devices on integrated circuits. It has been theoretically predicted that the voltage-control of magnetism in ferromagnetic/ferroelectric heterostructures can be significantly enhanced by utilizing high-K dielectrics. The critical challenge is how to enhance the permittivity of the ferroelectric film while maintaining low loss and low leakage characteristics and accomplishing this in an affordable manner by employing industry standard processing methods and large area low cost substrates. In this work we demonstrate the achievement of high-k, low loss and low leakage BST films utilizing optimized sputtered SrTiO3 buffer layers combined with a MOSD grown Mg-doped Ba0.60Sr0.40TiO3 overgrowth film on affordable large area substrates. Results of this research serves to promote enhanced EM coupling to enable a new class of charge mediated integratable voltage control multiferroic devices exploiting the converse ME effect.

  15. 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

  16. 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)

  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. Pulse and quench induced dynamical phase transition in a chiral multiferroic spin chain

    Science.gov (United States)

    Azimi, M.; Sekania, M.; Mishra, S. K.; Chotorlishvili, L.; Toklikishvili, Z.; Berakdar, J.

    2016-08-01

    Quantum dynamics of magnetic order in a chiral multiferroic chain is studied. We consider two different scenarios: ultrashort terahertz excitations or a sudden electric field quench. Performing analytical and numerical exact diagonalization calculations, we trace the pulse induced spin dynamics and extract quantities that are relevant to quantum information processing. In particular, we analyze the dynamics of the system chirality, the von Neumann entropy, and the pairwise and many-body entanglement. If the characteristic frequencies of the generated states are noncommensurate, then a partial loss of pair concurrence occurs. Increasing the system size, this effect becomes even more pronounced. Many-particle entanglement and chirality are robust and persist in the incommensurate phase. To analyze the dynamical quantum transitions for the quenched and pulsed dynamics we combined the Weierstrass factorization technique for entire functions and the Lanczos exact diagonalization method. For a small system we obtained analytical results including the rate function of the Loschmidt echo. Exact numerical calculations for a system up to 40 spins confirm phase transition. Quench-induced dynamical transitions have been extensively studied recently. Here we show that related dynamical transitions can be achieved and controlled by appropriate electric field pulses.

  19. 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.

  20. 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.

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

    Science.gov (United States)

    Dhir, Gitanjali; Uniyal, Poonam; Verma, N. K.

    2015-06-01

    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.

  2. Calcination temperature influenced multiferroic properties of Ca-doped BiFeO{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Dhir, Gitanjali, E-mail: gitanjali.thaprian@gmail.com; Uniyal, Poonam; Verma, N. K. [Nano Research Lab, School of Physics and Materials Science, Thapar University, Patiala-147004 (India)

    2015-06-24

    The influence of Ca-doping and particle size on structural, morphological and magnetic properties of BiFeO{sub 3} 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.

  3. Phase formation, dielectric and magnetic properties of bismuth ferrite–lead magnesium niobate multiferroic composites

    Energy Technology Data Exchange (ETDEWEB)

    Wongmaneerung, R., E-mail: re_nok@yahoo.com [Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Padchasri, J.; Tipakontitikul, R. [Department of Physics, Ubonratchathani University, Ubonratchathani 31490 (Thailand); Loan, T.H. [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, No. 1, Dai Co Viet, Hanoi (Viet Nam); Jantaratana, P. [Department of Physics, Kasetsart University, Bangkok 10900 (Thailand); Yimnirun, R. [School of Physics, Institute of Science, and NANOTEC-SUT Center of Excellence of Advanced Functional Nanomaterials, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Ananta, S. [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2014-09-01

    Highlights: • A bimodal particle size concept was designed in the production of BF–PMN composites. • A very abnormal diffuse dielectric pattern is observed during the heating process. • BF–PMN composites show highly saturated magnetization. - Abstract: Binary multiferroic composites (1−x)BiFeO{sub 3}–xPb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3} (BF–PMN; x = 0.0–50 wt%) were fabricated through a traditional ceramic process. The effect of the PMN contents on the phase assemblage, microstructure, dielectric and magnetic properties of the samples were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), LCR meter and vibrating sample magnetometer (VSM), respectively. The results indicate that all composites show that perovskite structure and PMN phase is compatible with the BF phase. The microstructure displays the mix phases between BF, PMN, Bi-rich BF and Fe-rich BF phases. Dielectric anomalies of these composites are totally different from BiFeO{sub 3} single phase. Moreover, the dielectric constant is found to increase as the content of PMN decreases. Magnetic transition temperatures are in the range of 270–440 °C. Interestingly, the M–H hysteresis loop measurements indicated that all composites exhibited weak ferromagnetism behavior at room temperature. The maximum remanent magnetization M{sub r} is observed for x = 30 wt% and then decreases when the PMN content is more than 40 wt%.

  4. Structural and magnetic properties of geometrically frustrated multiferroic ErMnO{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Raneesh, B. [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, Kerala 686 560 (India); Saha, A.; Das, D. [UGC-DAE Consortium for Scientific Research, Kolkata 700 098 (India); Kalarikkal, Nandakumar, E-mail: nkkalarikkal@mgu.ac.in [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, Kerala 686 560 (India); Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala 686 560 (India)

    2013-02-25

    Highlights: Black-Right-Pointing-Pointer Nano crystalline multiferroic ErMnO{sub 3} has been synthesized by the sol-gel method. Black-Right-Pointing-Pointer Significant size effect of antiferromagnetic transition in ErMnO{sub 3} nanoparticles was demonstrated by the ({chi}-T) magnetic measurements. Black-Right-Pointing-Pointer Indications of weak ferromagnetism in the form of a narrow hysteresis loop at 5 K. Black-Right-Pointing-Pointer A very weak magneto electric effect which was detected by a dynamic lock-in amplifier technique. - Abstract: Single phase hexagonal nanocrystalline ErMnO{sub 3} has been synthesized by the sol-gel method to study their structural and magnetic properties. Rietveld refinement of the X-ray powder diffraction data shows that the sample is single phase and crystallized in a hexagonal structure belonging to the P6{sub 3}cm space group. The magnetic characterization indicates that antiferromagnetic ordering of the Mn sublattice occurs at T{sub N} = 65 K. Indications of weak ferromagnetism in the form of a narrow hysteresis loop at 5 K and a very weak magnetoelectric (ME) coupling in ErMnO{sub 3} nanoparticles are attributed to intrinsic effects.

  5. 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.

  6. 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...

  7. 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 ...

  8. 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.

  9. 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.

  10. 多铁性材料BiFeO3的磁学、电学性质及磁电耦合效应%Magnetism, Ferroelectricity and Magnetoelectric Coupling of Multiferroic BiFeO3

    Institute of Scientific and Technical Information of China (English)

    张金星; 于浦

    2013-01-01

    The coexistence and coupling of the electric and magnetic order parameters can provide a novel platform to probe magne-toelectric effects in multiferroics. The potential applications of magnetoelectric coupling on future high-density, high-speed and low-energy-cost electronic devices stimulate material scientists and condense matter physicists to revisit multiferroic systems over the past decades. Owing to the high ferroelectric and Néel transition temperatures, BiFeO3 (BFO) appears to be one of the most promising candidates in the on-chip integrated magnetoelectronic devices and attracts people’s interests since 1960s. Especially, the appearance of high-quality BFO epitaxial thin films in 2003 has triggered the study of its intrinsic properties and physics behind. This article re-views the BFO research history and focuses on the cutting-edge achievements in BFO-related projects in the past decade. We mainly introduce the emerging physical phenomena from the aspects of crystalline structures, electrical/magnetic behaviors and magnetoelec-tric coupling in this multiferroic BFO, accompanying with a brief outlook in the conclusion.%  磁电多铁性材料中电荷和自旋序参量共存,并相互耦合在一起,产生磁电耦合效应。由于磁电耦合效应在未来高密度、低能耗、高读写速率器件的重要应用前景,近10年来,多铁性材料的研究成为了材料科学以及凝聚态物理领域的热点之一。BiFeO3不仅是为数不多的铁电反铁磁的多铁性材料之一,更难能可贵的是它的铁电Curie温度和反铁磁Néel温度都远高于室温。正因为如此,BiFeO3早在60多年前就受到人们的关注;但是直到2003年高质量外延薄膜的出现,才真正掀起了人们对其卓越性能和新奇物理现象研究的热潮。正是在这个背景下回顾BiFeO3的发展历史,着重介绍近10年此领域的研究成果:从晶体结构、电学性质(巨大铁电极化、电致阻

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Reversing ferroelectric polarization in multiferroic DyMn2O5 by nonmagnetic Al substitution of Mn

    Science.gov (United States)

    Zhao, Z. Y.; Liu, M. F.; Li, X.; Wang, J. X.; Yan, Z. B.; Wang, K. F.; Liu, J.-M.

    2014-08-01

    The multiferroic RMn2O5 family, where R is rare-earth ion or Y, exhibits rich physics of multiferroicity which has not yet well understood. DyMn2O5 is a representative member of this family. The ferroelectric polarization of DyMn2O5 is claimed to be magnetically relevant and have more than one component. Therefore, the polarization reversal upon the sequent magnetic transitions is expected. We investigate the evolution of the ferroelectric polarization upon a partial substitution of Mn3+ by nonmagnetic Al3+ in order to tailor the Mn3+-Mn4+ interactions and then to modulate the polarization in DyMn2-x/2Alx/2O5. It is revealed that the polarization can be successfully reversed by Al-substitution via substantially suppressing the Mn3+-Mn4+ interactions, while the Dy3+-Mn4+ interactions can sustain against the substitution until a level as high as x = 0.2. In addition, the independent Dy spin ordering is shifted remarkably down to an extremely low temperature due to the Al3+ substitution. The present work unveils the possibility of tailoring the Mn3+-Mn4+ and Dy3+-Mn4+ interactions independently, and thus reversing the ferroelectric polarization.

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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

    2016-08-01

    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.

  2. 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.

  3. New features from transparent thin films of EuTiO3

    Science.gov (United States)

    Stuhlhofer, B.; Logvenov, G.; Górny, M.; Roleder, K.; Boris, A.; Pröpper, D.; Kremer, R. K.; Köhler, J.; Bussmann-Holder, A.

    2016-08-01

    The almost multiferroic perovskite EuTiO3 (ETO) has been prepared as films on substrates of SrTiO3. For all prepared film thicknesses highly transparent insulating films with atomically flat surfaces and excellent orientation have been grown. They were characterized by X-ray diffraction, magnetic susceptibility and birefringence measurements and found to exhibit bulk properties, namely an antiferromagnetic transition at TN = 5.1 K and a structural transition at TS = 282 K. The latter could only be identified due to the high transparency of the samples since the optical band gap is of the order of 4.5 eV and larger than observed before for any bulk and thin film samples.

  4. 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.

  5. Probing ultrafast spin dynamics through a magnon resonance in the antiferromagnetic multiferroic HoMnO3

    Science.gov (United States)

    Bowlan, P.; Trugman, S. A.; Bowlan, J.; Zhu, J.-X.; Hur, N. J.; Taylor, A. J.; Yarotski, D. A.; Prasankumar, R. P.

    2016-09-01

    We demonstrate an approach for directly tracking antiferromagnetic (AFM) spin dynamics by measuring ultrafast changes in a magnon resonance. We test this idea on the multiferroic HoMnO3 by optically photoexciting electrons, after which changes in the spin order are probed with a THz pulse tuned to a magnon resonance. This reveals a photoinduced change in the magnon line shape that builds up over 5-12 picoseconds, which we show to be the spin-lattice thermalization time, indicating that electrons heat the spins via phonons. We compare our results to previous studies of spin-lattice thermalization in ferromagnetic manganites, giving insight into fundamental differences between the two systems. Our work sheds light on the microscopic mechanism governing spin-phonon interactions in AFMs and demonstrates a powerful approach for directly monitoring ultrafast spin dynamics.

  6. Magnetically frustrated behavior in multiferroics RMn2O5 (R =Bi, Eu, and Dy): A Raman scattering study

    Science.gov (United States)

    García-Flores, A. F.; Granado, E.; Martinho, H.; Rettori, C.; Golovenchits, E. I.; Sanina, V. A.; Oseroff, S. B.; Park, S.; Cheong, S.-W.

    2007-05-01

    A temperature dependent Raman scattering study in multiferroic single crystals RMn2O5 (R =Bi, Eu, and Dy) was performed. The Raman spectra were measured in the range from 150to450cm-1 involving mostly Mn-O-Mn bending vibrations, complementing our previous work in a higher frequency range involving Mn-O stretching modes. A number of studied phonons present anomalous frequency behavior below a characteristic temperature, T*˜60-65K, such as that found for the stretching modes. The sign and magnitude of such anomalous behavior appear to be correlated with the ionic radius of R, being softening for R =Bi and hardening for R =Eu and Dy in the range between TC/TN and T*. The anomalous phonon behaviors in both bending and stretching modes are consistent with an interpretation in terms of the spin-phonon coupling in a scenario of strong magnetic correlations.

  7. Electronic structure of multiferroic BiFeO3 by resonant soft-x-ray emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Higuchi, Tohru; Higuchi, T.; Liu, Y.-S.; Yao, P.; Glans, P.-A.; Guo, Jinghua; Chang, C.; Wu, Z.; Sakamoto, W.; Itoh, N.; Shimura, T.; Yogo, T.; Hattori, T.

    2008-07-11

    The electronic structure of multiferroic BiFeO{sub 3} has been studied using soft-X-ray emission spectroscopy. The fluorescence spectra exhibit that the valence band is mainly composed of O 2p state hybridized with Fe 3d state. The band gap corresponding to the energy separation between the top of the O 2p valence band and the bottom of the Fe 3d conduction band is 1.3 eV. The soft-X-ray Raman scattering reflects the features due to charge transfer transition from O 2p valence band to Fe 3d conduction band. These findings are similar to the result of electronic structure calculation by density functional theory within the local spin-density approximation that included the effect of Coulomb repulsion between localized d states.

  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. Electronic and crystal structure changes induced by in-plane oxygen vacancies in multiferroic YMn O3

    Science.gov (United States)

    Cheng, Shaobo; Li, Menglei; Meng, Qingping; Duan, Wenhui; Zhao, Y. G.; Sun, X. F.; Zhu, Yimei; Zhu, Jing

    2016-02-01

    The widely spread oxygen vacancies (VO) in multiferroic materials can strongly affect their physical properties. However, their exact influence has rarely been identified in hexagonal manganites. Here, with the combined use of transmission electron microscopy (TEM) and first-principles calculations, we have systematically studied the electronic and crystal structure modifications induced by VO located at the same Mn atomic plane (in-plane VO). Our TEM experiments reveal that the easily formed in-plane VO not only influence the electronic structure of YMn O3 but alter the in-plane Wyckoff positions of Mn ions, which may subsequently affect the intraplane and interplane exchange interaction of Mn ions. The ferroelectricity is also impaired due to the introduction of VO. Further calculations confirm these electronic and structural changes and modifications. Our results indicate that the electronic and crystal structure of YMn O3 can be manipulated by the creation of VO.

  11. 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)

  12. Enhancement of multiferroic properties of nanocrystalline BiFeO{sub 3} powder by Gd-doping

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, A. [Department of Physics, National Institute of Technology, Durgapur 713209 (India); Basu, S., E-mail: soumen.basu@phy.nitdgp.ac.in [Department of Physics, National Institute of Technology, Durgapur 713209 (India); Manna, P.K.; Yusuf, S.M. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Pal, M. [CSIR-Central Mechanical Engineering Research Institute, Durgapur 713209 (India)

    2014-06-15

    Highlights: • Large increase in magnetic moment. • Tremendous enhancement in resistivity. • Appreciable increase in dielectric constant. • P–E hysteresis loop at room temperature with enhanced polarizibility. • Appreciable increase in magneto-dielectric constant. - Abstract: Large leakage current and a very low magnetic moment are the two most disadvantages of BiFeO{sub 3} (BFO), which hinder the possibilities of its application in modern devices. An enhancement of the multiferroic properties of BFO is a real challenge to the scientific community. We are able to achieve improve magnetic, electric and magneto-dielectric (MD) properties of sol–gel prepared nanocrystalline BFO by virtue of the beneficial effect of gadolinium doping. The phase-purity and nanocrystalline nature of the samples have been confirmed by the X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. Both dc and ac electrical properties were measured to understand the detail charge transport mechanism. The dc electrical resistivity was found to arise due to a variable range hopping conduction mechanism. The variation of ac-conductivity, as a function of frequency in the range (20 Hz–1 MHz) and temperature (298–523 K), was explained on the basis of the correlated barrier hoping (CBH) conduction mechanism. The origin of the improved magnetic and electrical properties have been attributed to a possible suppression of the inhomogeneous magnetic spin structure and/or broken periodicity of the spin cycloid of BFO due to smaller crystallite size, and a decrease of the oxygen vacancies. Our findings demonstrate the fundamental importance of doping in enhancing the multiferroic properties, which would open up the possibility of using BFO in designing spintronic devices.

  13. Reversing ferroelectric polarization in multiferroic DyMn{sub 2}O{sub 5} by nonmagnetic Al substitution of Mn

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Z. Y.; Liu, M. F.; Li, X.; Wang, J. X.; Yan, Z. B.; Wang, K. F.; Liu, J.-M. [Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2014-08-07

    The multiferroic RMn{sub 2}O{sub 5} family, where R is rare-earth ion or Y, exhibits rich physics of multiferroicity which has not yet well understood. DyMn{sub 2}O{sub 5} is a representative member of this family. The ferroelectric polarization of DyMn{sub 2}O{sub 5} is claimed to be magnetically relevant and have more than one component. Therefore, the polarization reversal upon the sequent magnetic transitions is expected. We investigate the evolution of the ferroelectric polarization upon a partial substitution of Mn{sup 3+} by nonmagnetic Al{sup 3+} in order to tailor the Mn{sup 3+}-Mn{sup 4+} interactions and then to modulate the polarization in DyMn{sub 2−x/2}Al{sub x/2}O{sub 5}. It is revealed that the polarization can be successfully reversed by Al-substitution via substantially suppressing the Mn{sup 3+}-Mn{sup 4+} interactions, while the Dy{sup 3+}-Mn{sup 4+} interactions can sustain against the substitution until a level as high as x = 0.2. In addition, the independent Dy spin ordering is shifted remarkably down to an extremely low temperature due to the Al{sup 3+} substitution. The present work unveils the possibility of tailoring the Mn{sup 3+}-Mn{sup 4+} and Dy{sup 3+}-Mn{sup 4+} interactions independently, and thus reversing the ferroelectric polarization.

  14. Ferrielectricity in DyMn2O5: A golden touchstone for multiferroicity of RMn2O5 family

    Science.gov (United States)

    Liu, J.-M.; Dong, S.

    2015-06-01

    The RMn2O5 manganite compounds represent one class of multiferroic family with magnetic origins, which has been receiving continuous attention in the past decade. So far, our understanding of the magnetic origins for ferroelectricity in RMn2O5 is associated with the nearly collinear antiferromagnetic structure of Mn ions, while the exchange striction induced ionic displacements are the consequence of the spin frustration competitions. While this scenario may be applied to almost all RMn2O5 members, its limitation is either clear: the temperature-dependent behaviors of electric polarization and its responses to external stimuli are seriously materials dependent. These inconsistences raise substantial concern with the state-of-the-art physics of ferroelectricity in RMn2O5. In this mini-review, we present our recent experimental results on the roles of the 4f moments from R ions which are intimately coupled with the 3d moments from Mn ions. DyMn2O5 is a golden figure for illustrating these roles. It is demonstrated that the spin structure accommodates two nearly collinear sublattices which generate respectively two ferroelectric (FE) sublattices, enabling DyMn2O5 an emergent ferrielectric (FIE) system rarely identified in magnetically induced FEs. The evidence is presented from several aspects, including FIE-like phenomena and magnetoelectric responses, proposed structural model, and experimental check by nonmagnetic substitutions of the 3d and 4f moments. Additional perspectives regarding possible challenges in understanding the multiferroicity of RMn2O5 as a generalized scenario are discussed.

  15. 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.

  16. 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.

  17. Direct observation of temperature dependent magnetic domain structure of the multiferroic La{sub 0.66}Sr{sub 0.34}MnO{sub 3}/BiFeO{sub 3} bilayer system by x-ray linear dichroism- and x-ray magnetic circular dichroism-photoemission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mix, C.; Finizio, S.; Jakob, G.; Kläui, M. [Institut für Physik, Johannes Gutenberg Universität Mainz, Staudingerweg 7, D-55128 Mainz (Germany); Buzzi, M.; Nolting, F. [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Kronast, F. [Helmholtz-Zentrum-Berlin für Materialien und Energie GmbH, Albert-Einstein Straße 15, D-12489 Berlin (Germany)

    2014-05-21

    Low-thickness La{sub 0.66}Sr{sub 0.34}MnO{sub 3} (LSMO)/BiFeO{sub 3} (BFO) thin film samples deposited on SrTiO{sub 3} were imaged by high resolution x-ray microscopy at different temperatures. The ultra-thin thickness of the top layer allows to image both the ferromagnetic domain structure of LSMO and the multiferroic domain structure of the buried BFO layer, opening a path to a direct observation of coupling at the interface on a microscopic level. By comparing the domain size and structure of the BFO and LSMO, we observed that, in contrast to LSMO single layers, LSMO/BFO multilayers show a strong temperature dependence of the ferromagnetic domain structure of the LSMO. Particularly, at 40 K, a similar domain size for BFO and LSMO is observed. This indicates a persistence of exchange coupling on the microscopic scale at a temperature, where the exchange bias as determined by magnetometer measurements is vanishing.

  18. 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.

  19. 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.

  20. 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.

  1. Magnetic transition from the paramagnetic to long-period structure in RMn2O5 multiferroics: Renormalization group analysis of critical behavior

    Science.gov (United States)

    Men'shenin, V. V.

    2013-06-01

    A transition from the paramagnetic state to a long-period magnetic structure with an incommensurate wave vector along one crystallographic axis in RMn2O5 multiferroics is considered. An effective Hamiltonian for these oxides is constructed with allowance for spin fluctuations. Critical points are found, and their stability is analyzed using the renormalization group approach. It is shown that critical fluctuations in these compounds admit a second-order phase transition with respect to a multicomponent order parameter.

  2. Magnetoelectric coupling and spin-dependent tunneling in Fe/PbTiO3/Fe multiferroic heterostructure with a Ni monolayer inserted at one interface

    Science.gov (United States)

    Dai, Jian-Qing; Zhang, Hu; Song, Yu-Min

    2015-08-01

    We report on first-principles calculations of a Ni monolayer inserted at one interface in the epitaxial Fe/PbTiO3/Fe multiferroic heterostructure, focusing on the magnetoelectric coupling and the spin-dependent transport properties. The results of magnetoelectric coupling calculations reveal an attractive approach to realize cumulative magnetoelectric effects in the ferromagnetic/ferroelectric/ferromagnetic superlattices. The underlying physics is attributed to the combinations of several different magnetoelectric coupling mechanisms such as interface bonding, spin-dependent screening, and different types of magnetic interactions. We also demonstrate that inserting a Ni monolayer at one interface in the Fe/PbTiO3/Fe multiferroic tunnel junction is an efficient method to produce considerable tunneling electroresistance effect by modifying the tunnel potential barrier and the interfacial electronic structure. Furthermore, coexistence of tunneling magnetoresistance and tunneling electroresistance leads to the emergence of four distinct resistance states, which can be served as a multistate-storage device. The complicated influencing factors including bulk properties of the ferromagnetic electrodes, decay rates of the evanescent states in the tunnel barrier, and the specific interfacial electronic structure provide us promising opportunities to design novel multiferroic tunnel junctions with excellent performances.

  3. Magnetoelectric coupling and spin-dependent tunneling in Fe/PbTiO{sub 3}/Fe multiferroic heterostructure with a Ni monolayer inserted at one interface

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Jian-Qing, E-mail: djqkust@sina.com; Zhang, Hu; Song, Yu-Min [School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China)

    2015-08-07

    We report on first-principles calculations of a Ni monolayer inserted at one interface in the epitaxial Fe/PbTiO{sub 3}/Fe multiferroic heterostructure, focusing on the magnetoelectric coupling and the spin-dependent transport properties. The results of magnetoelectric coupling calculations reveal an attractive approach to realize cumulative magnetoelectric effects in the ferromagnetic/ferroelectric/ferromagnetic superlattices. The underlying physics is attributed to the combinations of several different magnetoelectric coupling mechanisms such as interface bonding, spin-dependent screening, and different types of magnetic interactions. We also demonstrate that inserting a Ni monolayer at one interface in the Fe/PbTiO{sub 3}/Fe multiferroic tunnel junction is an efficient method to produce considerable tunneling electroresistance effect by modifying the tunnel potential barrier and the interfacial electronic structure. Furthermore, coexistence of tunneling magnetoresistance and tunneling electroresistance leads to the emergence of four distinct resistance states, which can be served as a multistate-storage device. The complicated influencing factors including bulk properties of the ferromagnetic electrodes, decay rates of the evanescent states in the tunnel barrier, and the specific interfacial electronic structure provide us promising opportunities to design novel multiferroic tunnel junctions with excellent performances.

  4. 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.

  5. 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

  6. 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

  7. 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

  8. 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...

  9. 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

  10. 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.

  11. Observation of spontaneous ferroelectric polarization reversal in multiferroic Mn{sub 1−x}Ni{sub x}WO{sub 4} (x ≈ 0.16)

    Energy Technology Data Exchange (ETDEWEB)

    Song, Young-Sang; Chung, Jae-Ho, E-mail: jaehc@korea.ac.kr [Department of Physics, Korea University, Seoul 136-713 (Korea, Republic of); Woo Shin, Kwang; Hoon Kim, Kee [CeNSCMR, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Hwan Oh, In [Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-06-23

    In this Letter, we report the effect of replacing Mn{sup 2+} ions with Ni{sup 2+} on the ferroelectricity of multiferroic MnWO{sub 4} 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 T{sub C}. 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.

  12. 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.

  13. 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.

  14. The low-temperature crystal structure of the multiferroic melilite Ca2CoSi2O7.

    Science.gov (United States)

    Sazonov, Andrew; Hutanu, Vladimir; Meven, Martin; Roth, Georg; Kézsmárki, István; Murakawa, Hiroshi; Tokura, Yoshinori; Náfrádi, Bálint

    2016-02-01

    In the antiferromagnetic ground state, below TN ≃ 5.7 K, Ca2CoSi2O7 exhibits strong magnetoelectric coupling. For a symmetry-consistent theoretical description of this multiferroic phase, precise knowledge of its crystal structure is a prerequisite. Here we report the results of single-crystal neutron diffraction on Ca2CoSi2O7 at temperatures between 10 and 250 K. The low-temperature structure at 10 K was refined assuming twinning in the orthorhombic space group P2(1)2(1)2 with a 3 × 3 × 1 supercell [a = 23.52 (1), b = 23.52 (1), c = 5.030 (3) Å] compared with the high-temperature normal state [tetragonal space group P42(1)m, a = b ≃ 7.86, c ≃ 5.03 Å]. The precise structural parameters of Ca2CoSi2O7 at 10 K are presented and compared with the literature X-ray diffraction results at 130 and 170 K (low-temperature commensurate phase), as well as at ∼ 500 K (high-temperature normal phase). PMID:26830804

  15. 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

  16. 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

  17. Enhancement of magnetic and ferroelectric behaviour in (Ca, Co) co-doped HoMnO3 multiferroics

    Science.gov (United States)

    Rout, P. P.; Pradhan, S. K.; Das, S. K.; Samantaray, S.; Roul, B. K.

    2013-11-01

    The effect of sintering temperature on structural, electrical and magnetic behaviours of polycrystalline samples of Ho0.9Ca0.1Mn0.9Co0.1O3 prepared by the solid state reaction route sintered at three different temperature 1250 °C, 1350 °C, 1450 °C for 10 h are investigated. XRD, SEM, magnetization, dielectric and ferroelectric measurements were carried out. Experimental results showed the nucleation of orthorhombic phase as the sintering temperature increases from 1250 °C to 1450 °C. Ferroelectric (Tc) and antiferromagnetic transition temperature (TN) increases with increase in sintering temperature. Strong bifurcation of FC and ZFC curve in sample sintered at 1450 °C showed a clear onset of ferromagnetic state around 165 °K, which is confirmed from M to H graph at 165 °K. All the sample showed ferroelectric behaviour at room temperature which are leaky in nature. Sintering temperature along with Ca and Co doping in HoMnO3 ceramics plays an important role in phase transformation along with enhancement in multiferroic properties.

  18. 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.

  19. Room-temperature electric polarization induced by phase separation in multiferroic GdMn2O5

    Science.gov (United States)

    Khannanov, B. Kh.; Sanina, V. A.; Golovenchits, E. I.; Scheglov, M. P.

    2016-02-01

    It was generally accepted until recently that multiferroics RMn2O5 crystallized in the centrosymmetric space group Pbam and ferroelectricity in them could exist only at low temperatures due to the magnetic exchange striction. Recent comprehensive structural studies [V. Baledent et al., Phys. Rev. Lett. 114, 117601 (2015)] have shown that the actual symmetry of RMn2O5 at room temperature is a noncentrosymmetric monoclinic space group Pm, which allows room temperature ferroelectricity to exist. However, such a polarization has not yet been found. Our electric polarization loop studies of GdMn2O5 have revealed that a polarization does exist up to room temperature. This polarization occurs mainly in restricted polar domains that arise in the initial GdMn2O5 matrix due to phase separation and charge carrier self-organization. These domains are selfconsistent with the matrix, which leads to the noncentrosymmetricity of the entire crystal. The polarization is controlled by a magnetic field, thereby demonstrating the presence of magnetoelectric coupling. The lowtemperature ferroelectricity enhances the restricted polar domain polarization along the b axis.

  20. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Huong Giang, D.T., E-mail: giangdth@vnu.edu.vn [Nano Magnetic Materials and Devices Department, Faculty of Engineering Physics and Nanotechnology, VNU University of Engineering and Technology, Vietnam National University, Hanoi E3 Building, 144 Xuan Thuy Road, Cau Giay, Hanoi (Viet Nam); Thuc, V.N.; Duc, N.H. [Nano Magnetic Materials and Devices Department, Faculty of Engineering Physics and Nanotechnology, VNU University of Engineering and Technology, Vietnam National University, Hanoi E3 Building, 144 Xuan Thuy Road, Cau Giay, Hanoi (Viet Nam)

    2012-07-15

    Electric field-induced magnetic anisotropy has been realized in the spin-valve-based {l_brace}Ni{sub 80}Fe{sub 20}/Cu/Fe{sub 50}Co{sub 50}/IrMn{r_brace}/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: Black-Right-Pointing-Pointer Investigate electric field-induced magnetic anisotropy in spin-valve/piezoelectric. Black-Right-Pointing-Pointer Magnetization, magnetoresistance changes under electric field across piezoelectric. Black-Right-Pointing-Pointer Magnetization in magnetostrictive FeCo-layer rotates under a compressive stress. Black-Right-Pointing-Pointer This advance shows great implications for low-power electronics and spintronics.

  2. Structural, electrical, dielectric and magnetic properties of Mn-Nd substituted CoFeO3 nano sized multiferroics

    Directory of Open Access Journals (Sweden)

    Abdul Aziz

    2016-08-01

    Full Text Available A series of MnxCo1−xFe1−yNdyO3 (where x=0.0–1.0 & y=0.0–0.1 multiferroic nanocrystals was synthesized via sol-gel auto-combustion technique. The structure was confirmed by X-ray diffraction (XRD while morphology was investigated by scanning electron microscopy (SEM. The electrical resistivity was observed to increase from 2.14×107 to 8.77×109 Ω-cm and activation energy was found to increase from 0.64 to 0.75 eV, while the drift mobility decreased from 4.75×10−13 to 1.27×10−15 cm2 V−1 S−1 by the substitution of Mn and Nd contents. The dielectric constant, dielectric loss and dielectric loss factor decrease with frequency and Mn-Nd contents. The saturation magnetization was increased from 34 to 70 emu g−1 while the coercivity decreased from 705 to 262 Oe with the increase of substituents. The increase in electrical resistivity and saturation magnetization while decrease in dielectric parameters and coercivity make these nanomaterials suitable for applications in microwave devices and longitudinal magnetic recording media.

  3. 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.

  4. Strain mediated magnetoelectric coupling in a NiFe2O4–BaTiO3 multiferroic composite

    Science.gov (United States)

    Gorige, Venkataiah; Kati, Raju; Yoon, D. H.; Kumar, P. S. Anil

    2016-10-01

    In this paper we demonstrate significant magnetoelectric coupling in ferrimagnetic, NiFe2O4, and ferroelectric, BaTiO3, multiferroic composite bulk materials by measuring temperature dependent magnetization. X-ray diffraction, scanning electron microscopy and high resolution transmission electron microscopy data show that the two phases coexist with a highly crystalline and sharp interface without any detectable impurities, which enables significant magnetoelectric (ME) coupling. The temperature dependent magnetization data of the composite clearly show the jumps in magnetization curves at the structural phase transitions of BaTiO3, thereby indicating their origin in ME coupling. The change in coercivity of composite sample in different ferroelectric phases of BaTiO3 has been observed compared to the NiFe2O4 sample. The different lattice strains corresponding to different ferroelectric phases of BaTiO3 could be the driving force for modulating the magnetization and coercivity of the composite material. This is clear evidence of strain mediated ME coupling in ferrimagnetic and ferroelectric composite materials.

  5. Direct evidence for the spin cycloid in strained nanoscale bismuth ferrite thin films

    Science.gov (United States)

    Bertinshaw, Joel; Maran, Ronald; Callori, Sara J.; Ramesh, Vidya; Cheung, Jeffery; Danilkin, Sergey A.; Lee, Wai Tung; Hu, Songbai; Seidel, Jan; Valanoor, Nagarajan; Ulrich, Clemens

    2016-09-01

    Magnonic devices that utilize electric control of spin waves mediated by complex spin textures are an emerging direction in spintronics research. Room-temperature multiferroic materials, such as bismuth ferrite (BiFeO3), would be ideal candidates for this purpose. To realize magnonic devices, a robust long-range spin cycloid with well-known direction is desired, since it is a prerequisite for the magnetoelectric coupling. Despite extensive investigation, the stabilization of a large-scale uniform spin cycloid in nanoscale (100 nm) thin BiFeO3 films has not been accomplished. Here, we demonstrate cycloidal spin order in 100 nm BiFeO3 thin films through the careful choice of crystallographic orientation, and control of the electrostatic and strain boundary conditions. Neutron diffraction, in conjunction with X-ray diffraction, reveals an incommensurate spin cycloid with a unique [11] propagation direction. While this direction is different from bulk BiFeO3, the cycloid length and Néel temperature remain equivalent to bulk at room temperature.

  6. 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)

  7. 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).

  8. 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-...

  9. 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 ...

  10. 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...

  11. 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

  12. 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.

  13. 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.

  14. 'Active' Thin Sections

    NARCIS (Netherlands)

    De Rooij, M.R.; Bijen, J.M.J.M.

    1999-01-01

    Optical microscopy using thin sections has become more and more important over the last decade to study concrete. Unfortunately, this technique is not capable of studying actually hydrating cement paste. At Delft University of Technology a new technique has been developed using 'active' thin section

  15. Thin films on cantilevers

    NARCIS (Netherlands)

    Nazeer, Hammad

    2012-01-01

    The main goal of the work compiled in this thesis is to investigate thin films for integration in micro electromechanical systems (MEMS). The miniaturization of MEMS actuators and sensors without compromising their performance requires thin films of different active materials with specific propertie

  16. 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.

  17. 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}.

  18. 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.

  19. 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

  20. Effect of rare-earth (Er and Gd) substitution on the magnetic and multiferroic properties of DyFe0.5Cr0.5O3

    Science.gov (United States)

    Sharma, Mohit K.; Basu, Tathamay; Mukherjee, K.; Sampathkumaran, E. V.

    2016-10-01

    We report the results of our investigations on the influence of partial substitution of Er and Gd for Dy on the magnetic and magnetoelectric properties of DyFe0.5Cr0.5O3, which is known to be a multiferroic system. Magnetic susceptibility and heat capacity data, apart from confirming the occurrence of magnetic transitions at ~121 and 13 K in DyFe0.5Cr0.5O3, bring out that the lower transition temperature only is suppressed by rare-earth substitution. Multiferroic behavior is found to persist in Dy0.4Ln0.6Fe0.5Cr0.5O3 (Ln  =  Er and Gd). There is an evidence for magnetoelectric coupling in all these materials with qualitative differences in its behavior as the temperature is changed across these two transitions. Remnant electric polarization is observed for all the compounds. The most notable observation is that electric polarization is seen to get enhanced as a result of rare-earth substitution with respect to that in DyFe0.5Cr0.5O3. Interestingly, a similar trend is seen in the magnetocaloric effect, consistent with the existence of magnetoelectric coupling. The results thus provide evidence for the tuning of magnetoelectric coupling by rare-earth substitution in this family of oxides.

  1. Effect of rare-earth (Er and Gd) substitution on the magnetic and multiferroic properties of DyFe0.5Cr0.5O3.

    Science.gov (United States)

    Sharma, Mohit K; Basu, Tathamay; Mukherjee, K; Sampathkumaran, E V

    2016-10-26

    We report the results of our investigations on the influence of partial substitution of Er and Gd for Dy on the magnetic and magnetoelectric properties of DyFe0.5Cr0.5O3, which is known to be a multiferroic system. Magnetic susceptibility and heat capacity data, apart from confirming the occurrence of magnetic transitions at ~121 and 13 K in DyFe0.5Cr0.5O3, bring out that the lower transition temperature only is suppressed by rare-earth substitution. Multiferroic behavior is found to persist in Dy0.4Ln0.6Fe0.5Cr0.5O3 (Ln  =  Er and Gd). There is an evidence for magnetoelectric coupling in all these materials with qualitative differences in its behavior as the temperature is changed across these two transitions. Remnant electric polarization is observed for all the compounds. The most notable observation is that electric polarization is seen to get enhanced as a result of rare-earth substitution with respect to that in DyFe0.5Cr0.5O3. Interestingly, a similar trend is seen in the magnetocaloric effect, consistent with the existence of magnetoelectric coupling. The results thus provide evidence for the tuning of magnetoelectric coupling by rare-earth substitution in this family of oxides. PMID:27588356

  2. 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.

  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. 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.

  5. 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 $p \\in (0,1)$.

  6. 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.

  7. Thermodynamic theory of strain-mediated direct magnetoelectric effect in multiferroic film-substrate hybrids

    Energy Technology Data Exchange (ETDEWEB)

    Kukhar, V G [Visual Trading Systems LLC, St Petersburg Branch, 194044 St Petersburg (Russian Federation); Pertsev, N A [A F Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St Petersburg (Russian Federation); Kholkin, A L, E-mail: pertsev.domain@mail.ioffe.ru [Center for Research in Ceramics and Composite Materials (CICECO) and Department of Ceramics and Glass Engineering, University of Aveiro, 3810-193 Aveiro (Portugal)

    2010-07-02

    A nonlinear thermodynamic theory is developed for the strain-mediated direct magnetoelectric (ME) effect displayed by ferroelectric-ferromagnetic nanostructures. This effect results from transmission of magnetic-field-induced deformations of a thick ferromagnetic substrate to a thin ferroelectric overlayer, where the polarization changes due to lattice strains. The strain-dependent polarization and permittivity of an epitaxial nanolayer (few tens of nm thick) are calculated using the thermodynamic theory of single-domain ferroelectric films. The substrate magnetostrictive deformations are described phenomenologically, taking into account their nonlinear variation with magnetic field. The calculations show that ME polarization and voltage coefficients strongly depend on the initial strain state of the film. For BaTiO{sub 3} and PbTiO{sub 3} films deposited on Co{sub 0.8}Zn{sub 0.2}Fe{sub 2}O{sub 4}, the out-of-plane polarization and related ME coefficients are calculated numerically as a function of magnetic field parallel to the interface. For films stabilized in the monoclinic phase, this transverse ME response depends on the orientation of magnetic field relative to their in-plane crystallographic axes. The longitudinal ME coefficient is also evaluated and, for a substrate geometry minimizing the demagnetizing field, predicted to be comparable to the transverse one. For BaTiO{sub 3} and PbTiO{sub 3} films deposited on Terfenol-D, the calculations yield high ME polarization coefficients {approx} 10{sup -7} s m{sup -1} and giant ME voltage coefficients {approx} 50 V cm{sup -1} Oe{sup -1}.

  8. 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...

  9. 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...

  10. 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.

  11. VELO RF foil thinning

    CERN Document Server

    Van Dieten, Derk

    2013-01-01

    An overview of the project in thinning an aluminium foil for the VELO section of the LHCb experiment. The foil was to be thinned from 0.3 mm to 0.1 mm and this report describes the very first tests. Approximate etching was used and a vacuum test and metrology test was performed. The first results look promising as the piece remains vacuum tight after etching and the first metrology data shows a good etch with further development required

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. Magnetic, ferroelectric, and spin phonon coupling studies of Sr3Co2Fe24O41 multiferroic Z-type hexaferrite

    Science.gov (United States)

    Raju, N.; Shravan Kumar Reddy, S.; Ramesh, J.; Gopal Reddy, Ch.; Yadagiri Reddy, P.; Rama Reddy, K.; Sathe, V. G.; Raghavendra Reddy, V.

    2016-08-01

    The magnetic, Raman, ferroelectric, and in-field 57Fe Mössbauer studies of polycrystalline multiferroic Sr3Co2Fe24O41 are reported in this paper. From the magnetization studies, it is observed that the sample is soft magnetic in nature with low temperature magnetic spin transitions like longitudinal to transverse conical structure around 130 K and change in magnetic crystalline anisotropy from conical to planar structure at 250 K. Ferroelectric studies of the sample exhibit the spontaneous polarization at low temperature. Strong spin phonon and spin lattice coupling is observed through low temperature Raman spectroscopy. From the in-field 57Fe Mössbauer spectroscopy, spin up and spin down site occupations of Fe ions are calculated in the unit cell.

  2. 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.

  3. Resistive switching in ceramic multiferroic Bi{sub 0.9}Ca{sub 0.1}FeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Rubi, Diego, E-mail: rubi@tandar.cnea.gov.ar [GIA and INN, CAC-CNEA, 1650 San Martin (Argentina); Gomez-Marlasca, Fernando [GIA and INN, CAC-CNEA, 1650 San Martin (Argentina); Bonville, Pierre; Colson, Dorothee; Levy, Pablo [CEA Saclay, IRAMIS, SPEC (CNRS URA 2464), F-91191 Gif sur Yvette (France)

    2012-08-15

    We report resistive switching effects in polycrystalline samples of the multiferroic Bi{sub 0.9}Ca{sub 0.1}FeO{sub 3} with silver electrodes. Moessbauer spectroscopy shows that upon Ca-doping the Fe remains in a 3+ valence state, suggesting charge compensation through the creation of large amounts of oxygen vacancies. Electrical characterization shows that the oxide/metal resistance can be switched between high and low resistance states by applying voltage pulses. This process was shown to be forming free and a strong relaxation after switching was found. We rationalize our results by considering oxygen vacancies migration to and from the metal-oxide interface, resulting in variations of the Schottky potential barrier height that modulate the interface resistance.

  4. Magnetic and electrical studies of Ho0.9RE0.1CrO3 (RE = Gd and Yb multiferroics

    Directory of Open Access Journals (Sweden)

    Shubhra Mathur

    2016-09-01

    Full Text Available We report magnetic and electrical studies on multiferroic systems Ho0.9(RE0.1CrO3 where RE symbolizes rare earths like Gd and Yb. Solid state diffusion method has been used to synthesize the samples. Structural phase formation has been confirmed with the help of powder X-ray diffraction. Magnetization measurements show canted antiferromagnetic nature with a weak ferromagnetic phase. Néel temperature for Cr3+–Cr3+ ordering shifts to higher side with increasing radii of rare earth cations. Frequency (100 Hz to 1 MHz and temperature (300–650 K dependent resistivity measurements are suggestive of semiconducting nature of the samples.

  5. 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

  6. 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.

  7. Spin-wave and electromagnon dispersions in multiferroic MnWO4 as observed by neutron spectroscopy: Isotropic Heisenberg exchange versus anisotropic Dzyaloshinskii-Moriya interaction

    Science.gov (United States)

    Xiao, Y.; Kumar, C. M. N.; Nandi, S.; Su, Y.; Jin, W. T.; Fu, Z.; Faulhaber, E.; Schneidewind, A.; Brückel, Th.

    2016-06-01

    High-resolution inelastic neutron scattering reveals that the elementary magnetic excitations in multiferroic MnWO4 consist of low-energy dispersive electromagnons in addition to the well-known spin-wave excitations. The latter can well be modeled by a Heisenberg Hamiltonian with magnetic exchange coupling extending to the 12th nearest neighbor. They exhibit a spin-wave gap of 0.61(1) meV. Two electromagnon branches appear at lower energies of 0.07(1) and 0.45(1) meV at the zone center. They reflect the dynamic magnetoelectric coupling and persist in both the collinear magnetic and paraelectric AF1 phase and the spin spiral ferroelectric AF2 phase. These excitations are associated with the Dzyaloshinskii-Moriya exchange interaction, which is significant due to the rather large spin-orbit coupling.

  8. 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.

  9. 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

  10. 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.

  11. Structural and magnetic studies on (x)PbTiO{sub 3} – (1 − x)SrFe{sub 12}O{sub 19} composite multiferroics

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ajay; Singh, Vishal; Bamzai, K.K., E-mail: kkbamz@yahoo.com

    2015-04-01

    Lead titanate and strontium hexaferrite multiferroic composite with general formula (x)PbTiO{sub 3} – (1 − x)SrFe{sub 12}O{sub 19} (where x = 0.10, 0.20, 0.30 and 0.50) was prepared using solid state sintering method. Lead titanate and strontium hexaferrite phase formation was identified using X-ray diffraction technique, thus establishing diphase system without any secondary phase. Calculation of lattice parameter shows that the composite prefers hexagonal structure. The morphology of the formation of composite was seen through scanning electron microscopic technique. The morphological investigations show that the composites are dense, have fewer pores and ferroelectric grains are homogenously distributed in the ferrite matrix. The ferroelectric and ferromagnetic grains are identified on the basis of energy dispersive spectroscopy (EDS) studies. The magnetic behavior of the composites at room temperature display magnetic hysteresis loop, indicating that the composites are ferromagnetic. The value of saturation magnetization decreases with increase in ferroelectric content from x = 0.10 to 0.30, whereas for x = 0.50 it shows an increase. The magneto-capacitance shows a decrease in its value due to magnetostriction. - Highlights: • Composite multiferroic xPbTiO{sub 3} – (1 − x) SrFe{sub 12}O{sub 19} nanoparticles were prepared by solid state reaction method. • Magnetic hysteresis loop indicates the composite to be ferromagnetic. • Magneto dielectric values decreases due to magnetostriction. • Nanoparticle composite shows a strong magnetoelectric coupling for x = 0.30.

  12. Various properties of the 0.6BaTiO$_3$–0.4Ni$_{0.5}$Zn$_{0.5}$Fe$_2$O$_4$ multiferroic nanocomposite

    Indian Academy of Sciences (India)

    RENUKA CHAUHAN; R C SRIVASTAVA

    2016-10-01

    Structural, magnetic and ferroelectric properties of 0.6BaTiO$_3$–0.4(Ni$_{0.5}Zn$_{0.5}Fe$_2$O$_4$) multiferroic nanocomposite are presented here. The structural properties of the samples were studied by XRD and Raman spectroscopy which confirm the formation of BaTiO$_3$ (BTO) phase with a tetragonal perovskite structure and asmall secondary spinel phase due to the ferrite content. The magnetic and electric orderings were investigated by vibrating sample magnetometer (VSM) and ferroelectric ($P–E$) loop tracer at room temperature. The inceptionof ferroelectric properties is due to barium titanate. The remnant polarization increases ∼5 times for the composite with Ni$_{0.5}$Zn$_{0.5}$Fe$_2$O$_4$ (NZFO) substitution compared to BTO. The remnant polarization is conducive forswitching applications of multiferroic composite.

  13. 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

  14. 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.

  15. Modern Thin-Layer Chromatography.

    Science.gov (United States)

    Poole, Colin F.; Poole, Salwa K.

    1989-01-01

    Some of the important modern developments of thin-layer chromatography are introduced. Discussed are the theory and instrumentation of thin-layer chromatography including multidimensional and multimodal techniques. Lists 53 references. (CW)

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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...

  2. NMR characterization of thin films

    Science.gov (United States)

    Gerald, II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

    2008-11-25

    A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

  3. Electric-Field Control of Magnetism in Co40Fe40B20/(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 Multiferroic Heterostructures with Different Ferroelectric Phases.

    Science.gov (United States)

    Liu, Yan; Zhao, Yonggang; Li, Peisen; Zhang, Sen; Li, Dalai; Wu, Hao; Chen, Aitian; Xu, Yang; Han, X F; Li, Shiyan; Lin, Di; Luo, Haosu

    2016-02-17

    Electric-field control of magnetism in multiferroic heterostructures composed of Co40Fe40B20 (CoFeB) and (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) with different ferroelectric phases via changing composition and temperature is explored. It is demonstrated that the nonvolatile looplike bipolar-electric-field-controlled magnetization, previously found in the CoFeB/PMN-xPT heterostructures with PMN-xPT in the rhombohedral (R) phase around the morphotropic phase boundary (MPB), also occurs for PMN-xPTs with both R phase (far away from MPB) and monoclinic (M) phase, suggesting that the phenomenon is the common feature of CoFeB/PMN-xPT multiferroic heterostructures for PMN-xPT with different phases. The magnitude of the effect changes with increasing temperature and volatile bipolar-electric-field-controlled magnetization with a butterflylike behavior occurs when the ferroelectric phase changes to the tetragonal phase (T). Moreover, for the R-phase sample with x = 0.18, an abrupt and giant increase of magnetization is observed at a characteristic temperature in the temperature dependence of magnetization curve. These results are discussed in terms of coupling between magnetism and ferroelectric domains including macro- and microdomains for different ferroelectric phases. This work is helpful for understanding the phenomena of electric-field control of magnetism in FM/FE multiferroic heterostructures and is also important for applications.

  4. 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

  5. [Spectral emissivity of thin films].

    Science.gov (United States)

    Zhong, D

    2001-02-01

    In this paper, the contribution of multiple reflections in thin film to the spectral emissivity of thin films of low absorption is discussed. The expression of emissivity of thin films derived here is related to the thin film thickness d and the optical constants n(lambda) and k(lambda). It is shown that in the special case d-->infinity the emissivity of thin films is equivalent to that of the bulk material. Realistic numerical and more precise general numerical results for the dependence of the emissivity on d, n(lambda) and k(lambda) are given.

  6. 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.

  7. Thin film superfluid optomechanics

    CERN Document Server

    Baker, Christopher G; McAuslan, David L; Sachkou, Yauhen; He, Xin; Bowen, Warwick P

    2016-01-01

    Excitations in superfluid helium represent attractive mechanical degrees of freedom for cavity optomechanics schemes. Here we numerically and analytically investigate the properties of optomechanical resonators formed by thin films of superfluid $^4$He covering micrometer-scale whispering gallery mode cavities. We predict that through proper optimization of the interaction between film and optical field, large optomechanical coupling rates $g_0>2\\pi \\times 100$ kHz and single photon cooperativities $C_0>10$ are achievable. Our analytical model reveals the unconventional behaviour of these thin films, such as thicker and heavier films exhibiting smaller effective mass and larger zero point motion. The optomechanical system outlined here provides access to unusual regimes such as $g_0>\\Omega_M$ and opens the prospect of laser cooling a liquid into its quantum ground state.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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...

  13. 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

  14. 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...

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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...

  1. 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

  2. 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.

  3. Spin-phonon coupling, high-pressure phase transitions, and thermal expansion of multiferroic GaFeO3: A combined first principles and inelastic neutron scattering study

    Science.gov (United States)

    Gupta, Mayanak Kumar; Mittal, Ranjan; Zbiri, Mohamed; Singh, Ripandeep; Rols, Stephane; Schober, Helmut; Chaplot, Samrath Lal

    2014-10-01

    We have carried out an extensive phonon study on multiferroic GaFeO3 to elucidate its dynamical behavior. Inelastic neutron scattering measurements are performed over a wide temperature range, 150 to 1198 K. First principles lattice dynamical calculations are done for the sake of the analysis and interpretation of the observations. The comparison of the phonon spectra from magnetic and nonmagnetic calculations highlights pronounced differences. The energy range of the vibrational atomistic contributions of the Fe and O ions are found to differ significantly in the two calculation types. Therefore, magnetism induced by the active spin degrees of freedom of Fe cations plays a key role in stabilizing the structure and dynamics of GaFeO3. Moreover, the computed enthalpy in various phases of GaFeO3 is used to gain deeper insights into the high-pressure phase stability of this material. Further, the volume dependence of the phonon spectra is used to determine its thermal expansion behavior.

  4. 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)

  5. 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

  6. 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.

  7. 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)

  8. Helical order and multiferroicity in the S =1/2 quasi-kagome system KCu3As2O7(OD)3

    Science.gov (United States)

    Nilsen, G. J.; Okamoto, Y.; Ishikawa, H.; Simonet, V.; Colin, C. V.; Cano, A.; Chapon, L. C.; Hansen, T.; Mutka, H.; Hiroi, Z.

    2014-04-01

    Several Cu2+ hydroxide minerals have been recently identified as candidate realizations of the S=1/2 kagome Heisenberg model. In this context, we have studied the distorted system KCu3As2O7(OD)3 using neutron scattering and bulk measurements. Although the distortion favors magnetic order over a spin liquid ground state, refinement of the magnetic diffraction pattern below TN1=7.05(5) K yields a complex helical structure with k =(0.77,0,0.11). This structure, as well as the spin excitation spectrum, are well described by a classical Heisenberg model with ferromagnetic nearest neighbor couplings. Multiferroicity is observed below TN1, with an unusual crossover between improper and pseudoproper behavior occurring at TN2=5.5 K. The polarization at T =2 K is P =1.5μCm-2. The properties of KCu3As2O7(OD)3 highlight the variety of physics which arise from the interplay of spin and orbital degrees of freedom in Cu2+ kagome systems.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Exchange bias effect in multiferroic CoCr2O4/Cr2O3 nanogranular system synthesized through a phase segregation route

    Science.gov (United States)

    Tian, Zhaoming; Chen, Jingting; Yuan, Songliu; Tang, Jianbang; Huo, Shaoxin; Duan, Hanning

    2011-09-01

    A nanogranular system of multiferroic CoCr2O4 nanoparticles embedded in an antiferromagnetic Cr2O3 matrix has been synthesized through a high-temperature phase segregation route from a Co-doped Cr2O3 matrix. Magnetic studies show that exchange bias fields (HEB) accompanying vertical magnetization shifts (MShift) are observed at low temperatures after field cooled from 350 K. The corresponding exchange bias field can be as large as 1420 Oe, and the vertical magnetization shift reaches 0.116 emu/g at 10 K. The exchange bias field decreases with temperature increasing and disappears at T ≈ 70 K, while the coercive field (HC) initially increases with the temperature up to 40 K, and thereafter, it decreases to zero at 100 K. This exchange bias behavior is discussed in terms of the existence of exchange coupling between the ferrimagnetic CoCr2O4 core and spin glass-like phase at the interfaces.

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Thin film interconnect processes

    Science.gov (United States)

    Malik, Farid

    Interconnects and associated photolithography and etching processes play a dominant role in the feature shrinkage of electronic devices. Most interconnects are fabricated by use of thin film processing techniques. Planarization of dielectrics and novel metal deposition methods are the focus of current investigations. Spin-on glass, polyimides, etch-back, bias-sputtered quartz, and plasma-enhanced conformal films are being used to obtain planarized dielectrics over which metal films can be reliably deposited. Recent trends have been towards chemical vapor depositions of metals and refractory metal silicides. Interconnects of the future will be used in conjunction with planarized dielectric layers. Reliability of devices will depend to a large extent on the quality of the interconnects.

  2. The religion of thinness

    Directory of Open Access Journals (Sweden)

    Michelle Lelwica

    2011-01-01

    Full Text Available This paper examines the almost religious-like devotion of especially women in pursuing the goal of a thinner body. The quest for a slender body is analysed as a ‘cultural religion’, which the author calls the ‘Religion of Thinness’. The analysis revolves around four observations. The first is that for many women in the US today, the quest for a slender body serves what has historically been a ‘religious’ function: providing a sense of purpose that orients and gives meaning to their lives, especially in times of suffering and uncertainty. Second, this quest has many features in common with traditional religions, including beliefs, myths, rituals, moral codes, and sacred images—all of which encourage women to find ‘salvation’ (i.e., happiness and well-being through the pursuit of a ‘better’ (i.e., thinner body.Third, this secular faith draws so many adherents in large part because it appeals to and addresses what might be referred to as spiritual needs—including the need for a sense of purpose, inspiration, security, virtue, love, and well-being—even though it shortchanges these needs, and, in the long run, fails to deliver the salvation it promises. Fourth, a number of traditional religious ideas, paradigms and motifs tacit­ly inform and support the Religion of Thinness. More specifically, its soteri­ology resurrects and recycles the misogynist, anti-body, other-worldly, and exclusivist aspects of patriarchal religion. Ultimately, the analysis is not only critical of the Religion of Thinness; it also raises suspicions about any clear-cut divisions between ‘religion’, ‘culture’, and ‘the body’. In fact, examining the functions, features, and ideologies embedded in this secular devotion gives us insight into the constitutive role of the body in the production and apprehension of religious and cultural meanings.

  3. 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 ...

  4. 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.

  5. 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...

  6. 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.

  7. 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

  8. 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

  9. Chiral atomically thin films

    Science.gov (United States)

    Kim, Cheol-Joo; Sánchez-Castillo, A.; Ziegler, Zack; Ogawa, Yui; Noguez, Cecilia; Park, Jiwoong

    2016-06-01

    Chiral materials possess left- and right-handed counterparts linked by mirror symmetry. These materials are useful for advanced applications in polarization optics, stereochemistry and spintronics. In particular, the realization of spatially uniform chiral films with atomic-scale control of their handedness could provide a powerful means for developing nanodevices with novel chiral properties. However, previous approaches based on natural or grown films, or arrays of fabricated building blocks, could not offer a direct means to program intrinsic chiral properties of the film on the atomic scale. Here, we report a chiral stacking approach, where two-dimensional materials are positioned layer-by-layer with precise control of the interlayer rotation (θ) and polarity, resulting in tunable chiral properties of the final stack. Using this method, we produce left- and right-handed bilayer graphene, that is, a two-atom-thick chiral film. The film displays one of the highest intrinsic ellipticity values (6.5 deg μm-1) ever reported, and a remarkably strong circular dichroism (CD) with the peak energy and sign tuned by θ and polarity. We show that these chiral properties originate from the large in-plane magnetic moment associated with the interlayer optical transition. Furthermore, we show that we can program the chiral properties of atomically thin films layer-by-layer by producing three-layer graphene films with structurally controlled CD spectra.

  10. Effect of dysprosium substitution on structural and dielectric properties of BiFeO3-PbTiO3 multiferroic composites

    Institute of Scientific and Technical Information of China (English)

    N.K. Mohanty; A.K. Behera; S.K. Satpathy; Banarji Behera; P. Nayak

    2015-01-01

    0.5BiDyxFe1–xO3-0.5PbTiO3(0.5BDxF1–x-0.5PT) (x=0.00, 0.05, 0.10, 0.15, 0.20) multiferroic composites were pre-pared by conventional solid state reaction method. Structural characterization was performed by X-ray diffraction and the mate-rials showed tetragonal structure at room temperature. Surface morphology of the composites was studied by a scanning electron microscope (SEM). Frequency and temperature dependence of dielectric constant(εr)and dielectric loss (tanδ) of 0.5BDxF1–x- 0.5PT were measured in a wide range of frequency (100 Hz to 1 MHz) and temperature (25 to 400 ºC). The analysis of the study showed that theεr and tanδdecreased with increasing frequency in the given range for all the samples which could be explained through the occurrence of dipole relaxation process. The effect of substitution of rare earth element dysprosium (Dy) showed increase inεrin all the samples prepared for different concentrations from 0.00 to 0.20. An explanation for high value ofεr for Dy modified 0.5BiFeO3-0.5PbTiO3 (0.5BF-0.5PT) compared to Gd modified 0.5BF-0.5PT was provided. The variation of AC conductivity with inverse temperature found to obey the Arrhenius equation and the composites showed negative temperature coefficient of resistance (NTCR) behavior. The activation energy was found to be in the range from 0.25 to 0.40 eV for all the studied samples.

  11. Nuclear and magnetic supercells in the multiferroic candidate: Pb{sub 3}TeMn{sub 3}P{sub 2}O{sub 14}

    Energy Technology Data Exchange (ETDEWEB)

    Silverstein, Harlyn J., E-mail: umsilve3@myumanitoba.ca [Department of Chemistry, Parker Building University of Manitoba, Winnipeg, MB, Canada R3T2N2 (Canada); Huq, Ashfia [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6477 (United States); Lee, Minseong; Choi, Eun Sang [National High Magnetic Field Laboratory, Tallahassee, FL 32310-3706 (United States); Zhou, Haidong [Department of Physics and Astronomy, University of Tennessee-Knoxville, Knoxville, TN 37996-1200 (United States); Wiebe, Christopher R. [Department of Chemistry, Parker Building University of Manitoba, Winnipeg, MB, Canada R3T2N2 (Canada); Department of Chemistry, University of Winnipeg, Winnipeg, MB, Canada R3B2E9 (Canada); Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada L8S4M1 (Canada)

    2015-01-15

    The dugganites, Te{sup 6+}-containing members of the langasite series, have attracted recent interest due to their complex low-temperature magnetic unit cells, magnetodielectric, and potentially multiferroic properties. For Pb{sup 2+}-containing dugganites, a large monoclinic supercell was reported and was found to have a profound effect on the low temperature magnetism and spin excitation spectra. Pb{sub 3}TeMn{sub 3}P{sub 2}O{sub 14} is another dugganite previously shown to distort away from the canonical P321 langasite unit cell, although this supercell was never fully solved. Here we report the full crystal and magnetic structure solution of Pb{sub 3}TeMn{sub 3}P{sub 2}O{sub 14} using synchrotron x-ray and neutron diffraction data: a large trigonal supercell is observed in this material, which is believed to be the first supercell of its kind in the langasite family. Here, the magnetic structure, high-magnetic field behavior, and dielectric properties of Pb{sub 3}TeMn{sub 3}P{sub 2}O{sub 14} are presented. In addition to showing weak magnetoelectric behavior similar to other langasites, it was found that a phase transition occurs at 3 T near the antiferromagnetic transition temperature. - Graphical abstract: The nuclear supercell of Pb{sub 3}TeMn{sub 3}P{sub 2}O{sub 14}, found through joint refinements using high resolution synchrotron X-ray and neutron powder diffraction, retains the trigonal symmetry of the subcell. - Highlights: • Large P3 supercell found in Pb{sub 3}TeMn{sub 3}P{sub 2}O{sub 14}. • Complex helical spin structures below T{sub N}=6.6 K. • Phase transition at 3 T found using through dielectric and DC susceptibility measurements. • Moment saturation near 25 T at 1.4 K.

  12. Self-assembly of multiferroic core-shell particulate nanocomposites through DNA-DNA hybridization and magnetic field directed assembly of superstructures

    Directory of Open Access Journals (Sweden)

    Gollapudi Sreenivasulu

    2016-04-01

    Full Text Available 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.

  13. 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.

  14. 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.

  15. 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...

  16. 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.

  17. 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

  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. Ferromagnetic and multiferroic interfaces in granular perovskite composite xLa0.5Sr0.5CoO3-(1-x)BiFeO3

    Science.gov (United States)

    Lohr, Javier H.; López, Carlos A.; Saleta, Martín E.; Sánchez, Rodolfo D.

    2016-08-01

    Nanopowder of ferromagnetic La0.5Sr0.5CoO3 (LSCO) and multiferroic BiFeO3 (BFO) were synthesized by spray pyrolysis method. Different compositions of multiferroic xLSCO-(1-x)BFO composites were synthesized at 800 °C for 2 h. Scanning electron microscopy and energy dispersive spectroscopy elemental mapping were performed to study the morphology of composites. Ferri/ferromagnetic responses above TC (LSCO) are observed, which are associated with the interfaces LSCO/BFO. This interface presents a different behavior compared to the original perovskites, and the magnitude of the magnetization depends on x. Electrical DC conductivity as a function of temperature for LSCO nanopowder (x = 1) presents a different behavior than that reported in bulk material. For x = 1 and 0.9, the model by Glazman and Matveev [Zh. Eksp. Teor. Fiz. 94, 332 (1988)] is proposed to describe the electrical conductivity. On the other hand, x = 0, 0.1, and 0.5 present a variable range hopping behavior. Complex impedance spectroscopy as a function of frequency indicates a pure resistive behavior for x ≥ 0.5 compositions, while a complex resistive-capacitive behavior is observed for low x values (0, 0.1). In these samples, low values of magnetoelectric coupling were measured with an AC lock-in technique.

  20. 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.

  1. 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.

  2. Studies on Thin-shells and Thin-shell Wormholes

    CERN Document Server

    Övgün, Ali

    2016-01-01

    The study of traversable wormholes is very hot topic for the past 30 years. One of the best possible way to make traversable wormhole is using the thin-shells to cut and paste two spacetime which has tunnel from one region of space-time to another, through which a traveler might freely pass in wormhole throat. These geometries need an exotic matter which involves a stress-energy tensor that violates the null energy condition. However, this method can be used to minimize the amount of the exotic matter. The goal of this thesis study is to study on thin-shell and thin-shell wormholes in general relativity in 2+1 and 3+1 dimensions. We also investigate the stability of such objects.

  3. 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.

  4. 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.

  5. Raman scattering spectra, magnetic and ferroelectric properties of BiFeO{sub 3}–CoFe{sub 2}O{sub 4} nanocomposite thin films structure

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, Mintu [School of Physics and Materials Science, Thapar University, Patiala 147004, Punjab (India); Kumari, Mukesh; Chatterjee, Ratnamala [Magnetics and Advanced Ceramics Laboratory, Department of Physics, Indian Institute of Technology, Delhi 110016 (India); Sharma, Puneet, E-mail: puneet.sharma@thapar.edu [School of Physics and Materials Science, Thapar University, Patiala 147004, Punjab (India)

    2014-09-01

    Multiferroic (1−x)BiFeO{sub 3}(BFO)–xCoFe{sub 2}O{sub 4}(CFO) (x=0 and 0.1) nanocomposite thin films were deposited on ITO coated glass using sol–gel spin coating technique. X-ray diffraction and transmission electron microscopy examinations confirm the coexistence of both perovskite BFO and spinel CFO phases. The effect of addition of CFO in BFO matrix has been studied on Raman spectra, magnetic and ferroelectric properties. BFO/CFO nanocomposite showed good magnetic behavior (M{sub s}∼40.3 emu/cm{sup 3}, M{sub r}∼12.9 emu/cm{sup 3}, H{sub c}∼90 Oe) with no change in ferroelectric properties. The strain analysis carried out by Raman spectroscopy reveals that both BFO and CFO bands are found to be strained in BFO/CFO composite nanostructure. The strain of the bands is discussed on the basis of lattice mismatch (interfacial stress) between CFO (a=0.839 nm) and BFO (a=0.396 nm) phases.

  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. [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

  8. 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......, the bottom plate is lowered under gravity to produce a specified strain. The sample is thereby stretched into a filament. Provided the filament is sufficiently long, surface tension will induce a thinning of the filament until breakup in finite time. The numerical simulations are performed with a Lagrangian...

  9. 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.)

  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. 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

  12. Birefringent non-polarizing thin film design

    Institute of Scientific and Technical Information of China (English)

    QI; Hongji; HONG; Ruijin; HE; Hongbo; SHAO; Jianda; FAN; Zh

    2005-01-01

    In this paper, 2×2 characteristic matrices of uniaxially anisotropic thin film for extraordinary and ordinary wave are deduced at oblique incidence. Furthermore, the reflectance and transmittance of thin films are calculated separately for two polarizations, which provide a new concept for designing non-polarizing thin films at oblique incidence. Besides, using the multilayer birefringent thin films, non-polarizing designs, such as beam splitter thin film at single wavelength, edge filter and antireflection thin film over visible spectral region are obtained at oblique incidence.

  13. 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.

  14. 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.

  15. 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.

  16. Observability inequalities for thin shells

    Institute of Scientific and Technical Information of China (English)

    柴树根; 姚鹏飞

    2003-01-01

    We consider the exact controllability problem from boundary for thin shells. Under some check-able geometric assumptions on the middle surface, we establish the observability inequalities via the Bochnertechnique for the Dirichlet control and the Neumann control problems. We also give several examples to verifythe geometric assumptions.

  17. High Performance Thin Layer Chromatography.

    Science.gov (United States)

    Costanzo, Samuel J.

    1984-01-01

    Clarifies where in the scheme of modern chromatography high performance thin layer chromatography (TLC) fits and why in some situations it is a viable alternative to gas and high performance liquid chromatography. New TLC plates, sample applications, plate development, and instrumental techniques are considered. (JN)

  18. Capillary thinning of polymeric filaments

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Szabo, Peter; Hassager, Ole

    1998-01-01

    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...

  19. Shear Thinning of Noncolloidal Suspensions

    Science.gov (United States)

    Vázquez-Quesada, Adolfo; Tanner, Roger I.; Ellero, Marco

    2016-09-01

    Shear thinning—a reduction in suspension viscosity with increasing shear rates—is understood to arise in colloidal systems from a decrease in the relative contribution of entropic forces. The shear-thinning phenomenon has also been often reported in experiments with noncolloidal systems at high volume fractions. However its origin is an open theoretical question and the behavior is difficult to reproduce in numerical simulations where shear thickening is typically observed instead. In this letter we propose a non-Newtonian model of interparticle lubrication forces to explain shear thinning in noncolloidal suspensions. We show that hidden shear-thinning effects of the suspending medium, which occur at shear rates orders of magnitude larger than the range investigated experimentally, lead to significant shear thinning of the overall suspension at much smaller shear rates. At high particle volume fractions the local shear rates experienced by the fluid situated in the narrow gaps between particles are much larger than the averaged shear rate of the whole suspension. This allows the suspending medium to probe its high-shear non-Newtonian regime and it means that the matrix fluid rheology must be considered over a wide range of shear rates.

  20. Thin Film Solid Lubricant Development

    Science.gov (United States)

    Benoy, Patricia A.

    1997-01-01

    Tribological coatings for high temperature sliding applications are addressed. A sputter-deposited bilayer coating of gold and chromium is investigated as a potential solid lubricant for protection of alumina substrates during sliding at high temperature. Evaluation of the tribological properties of alumina pins sliding against thin sputtered gold films on alumina substrates is presented.

  1. Thin film polymeric gel electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Derzon, Dora K. (1554 Rosalba St. NE., Albuquerque, Bernalillo County, NM 87112); Arnold, Jr., Charles (3436 Tahoe, NE., Albuquerque, Bernalillo County, NM 87111); Delnick, Frank M. (9700 Fleming Rd., Dexter, MI 48130)

    1996-01-01

    Novel hybrid thin film electrolyte, based on an organonitrile solvent system, which are compositionally stable, environmentally safe, can be produced efficiently in large quantity and which, because of their high conductivities .apprxeq.10.sup.-3 .OMEGA..sup.-1 cm.sup.-1 are useful as electrolytes for rechargeable lithium batteries.

  2. 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.

  3. Semiconductor-nanocrystal/conjugated polymer thin films

    Science.gov (United States)

    Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

    2010-08-17

    The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

  4. Microstructure of epitaxial thin films of the ferromagnetic shape memory alloy Ni{sub 2}MnGa

    Energy Technology Data Exchange (ETDEWEB)

    Eichhorn, Tobias

    2011-12-09

    This work is concerned with the preparation and detailed characterization of epitaxial thin films of the Heusler compound Ni{sub 2}MnGa. This multiferroic compound is of both technological and scientific interest due to the outstanding magnetic shape memory (MSM) behavior. Huge magnetic-field-induced strains up to 10 % have been observed for single crystals close to a Ni{sub 2}MnGa composition. The effect is based on a redistribution of crystallographic twin variants of tetragonal or orthorhombic symmetry. Under the driving force of the external magnetic field twin boundaries can move through the crystal, which largely affects the macroscopic shape. The unique combination of large reversible strain, high switching frequency and high work output makes the alloy a promising actuator material. Since the MSM effect results from an intrinsic mechanism, MSM devices possess great potential for implementation in microsystems, e.g. microfluidics. So far significant strains, in response to an external magnetic field, have been observed for bulk single crystals and foams solely. In order to take advantage of the effect in applications concepts for miniaturization are needed. The rather direct approach, based on epitaxial thin films, is explored in the course of this work. This involves sample preparation under optimized deposition parameters and fabrication of freestanding single-crystalline films. Different methods to achieve freestanding microstructures such as bridges and cantilevers are presented. The complex crystal structure is extensively studied by means of X-ray diffraction. Thus, the different crystallographic twin variants that are of great importance for the MSM effect are identified. In combination with microscopy the twinning architecture for films of different crystallographic orientation is clarified. Intrinsic blocking effects in samples of (100) orientation are explained on basis of the variant configuration. In contrast, a promising twinning microstructure

  5. Thin films under chemical stress

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    The goal of work on this project has been develop a set of experimental tools to allow investigators interested in transport, binding, and segregation phenomena in composite thin film structures to study these phenomena in situ. Work to-date has focuses on combining novel spatially-directed optical excitation phenomena, e.g. waveguide eigenmodes in thin dielectric slabs, surface plasmon excitations at metal-dielectric interfaces, with standard spectroscopies to understand dynamic processes in thin films and at interfaces. There have been two main scientific thrusts in the work and an additional technical project. In one thrust we have sought to develop experimental tools which will allow us to understand the chemical and physical changes which take place when thin polymer films are placed under chemical stress. In principle this stress may occur because the film is being swelled by a penetrant entrained in solvent, because interfacial reactions are occurring at one or more boundaries within the film structure, or because some component of the film is responding to an external stimulus (e.g. pH, temperature, electric field, or radiation). However all work to-date has focused on obtaining a clearer understanding penetrant transport phenomena. The other thrust has addressed the kinetics of adsorption of model n-alkanoic acids from organic solvents. Both of these thrusts are important within the context of our long-term goal of understanding the behavior of composite structures, composed of thin organic polymer films interspersed with Langmuir-Blodgett (LB) and self-assembled monolayers. In addition there has been a good deal of work to develop the local technical capability to fabricate grating couplers for optical waveguide excitation. This work, which is subsidiary to the main scientific goals of the project, has been successfully completed and will be detailed as well. 41 refs., 10 figs.

  6. Magnetic and dielectric proprieties of multiferroic (1-x)Pb(Fe2/3W1/3)O3 -XPbTiO3 Ceramics prepared via a modified two-stage solid-state reaction

    OpenAIRE

    Bárbara Maraston Fraygola; Adelino de Aguiar Coelho; Ducinei Garcia; José Antônio Eiras

    2011-01-01

    Multiferroic Pb(Fe2/3W1/3)O3-PbTiO3 (PFW-PT) ceramics were synthesized via a modified two-stage solid-state reaction. This method utilized Fe2WO6, prepared at a first-stage, which was subsequently reacted with a stoichiometric amount of PbO and TiO2 at the second stage. This procedure efficiently suppressed the formation of lead tungstates and leads to getting dense ceramics. Electric and dielectric properties of (1-x)Pb(Fe2/3W1/3)O3 -xPbTiO3 solid solutions were investigated as a function of...

  7. Simple top-down preparation of magnetic Bi0.9Gd0.1Fe1−xTixO3 nanoparticles by ultrasonication of multiferroic bulk material

    DEFF Research Database (Denmark)

    Basith, M. A.; Ngo, Duc-The; Quader, A.;

    2014-01-01

    We present a simple technique to synthesize ultrafine nanoparticles directly from bulk multiferroic perovskitepowder. The starting materials, which were ceramic pellets of the nominal compositions Bi0.9Gd0.1-Fe1−xTixO3 (x = 0.00–0.20), were prepared initially by a solid state reaction technique......, then ground intomicrometer-sized powders and mixed with isopropanol or water in an ultrasonic bath. The particle sizewas studied as a function of sonication time with transmission electron microscopic imaging and electrondiffraction that confirmed the formation of a large fraction of single......-crystalline nanoparticles with a meansize of 11–13 nm. A significant improvement in the magnetic behavior of Bi0.9Gd0.1Fe1−xTixO3 nanoparticlescompared to their bulk counterparts was observed at room temperature. This sonication technique may beconsidered as a simple and promising route to prepare ultrafine nanoparticles...

  8. Strain-mediated voltage control of magnetism in multiferroic Ni77Fe23/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 heterostructure

    Science.gov (United States)

    Gao, Ya; Hu, Jiamian; Shu, Li; Nan, C. W.

    2014-04-01

    Using voltage-modified anisotropic magnetoresistance (AMR) measurement, we demonstrated a strain-mediated voltage control of magnetism in multiferroic Ni77Fe23(NiFe, 10 nm)/Pb (Mg1/3Nb2/3)0.7Ti0.3O3(PMN-PT, bulk crystal) heterostructure, even assuming a very small magnetostriction (˜0.3 ppm) for the NiFe film which has a composition close to bulk permalloy (Ni80Fe20). Influence of the magnitude of the rotating magnetic field used for AMR tests is studied. Combined AMR and theoretical analysis indicate the voltage-modified change in the magnetoresistance of the NiFe film arises from the reduced free energy barrier between the magnetic easy axis and hard axis via voltage-induced strains in the PMN-PT.

  9. Microwave Characterization of Pb0.45Ca0.55(Fe0.5Nb0.5)1- x Sn x O3 Multiferroics at X-Band

    Science.gov (United States)

    Singh, Charanjeet; Kaur, Randeep; Bindra Narang, S.; Puri, Maalti; Dhiman, Tanvi; Kaur, Harpreet

    2016-10-01

    The microwave characteristics of Pb0.45Ca0.55(Fe0.5Nb0.5)1- x Sn x O3 multiferroics ( x = 0.03, 0.06, 0.09, 0.12, 0.15) have been investigated as a function of frequency (8-12 GHz) and thickness for different substitutions of Sn4+ ions. The absorber testing device method is used to study microwave properties in the rectangular slotted waveguide. The condition of microwave signal after passing through different compositions has been reported. The quarter wavelength criterion is used to evaluate the microwave absorption. The large microwave absorption is observed at lower as well as higher substitution. Maximum reflected power has been found at higher substitution. The different compositions for electromagnetic applications have also been put forth.

  10. Matérn thinned Cox processes

    DEFF Research Database (Denmark)

    Andersen, Ina Trolle; Hahn, Ute

    2016-01-01

    and hard core behaviour can be achieved by applying a dependent Matérn thinning to a Cox process. An exact formula for the intensity of a Matérn thinned shot noise Cox process is derived from the Palm distribution. For the more general class of Matérn thinned Cox processes, formulae for the intensity...

  11. Matérn thinned Cox processes

    DEFF Research Database (Denmark)

    Andersen, Ina Trolle; Hahn, Ute

    of clustering and hard core behaviour can be achieved by applying a dependent Matérn thinning to a Cox process. An exact formula for the intensity of a Matérn thinned shot noise Cox process is derived from the Palm distribution. For the more general class of Matérn thinned Cox processes, formulae...

  12. Thinning spatial point processes into Poisson processes

    DEFF Research Database (Denmark)

    Møller, Jesper; Schoenberg, Frederic Paik

    2010-01-01

    are identified, and where we simulate backwards and forwards in order to obtain the thinned process. In the case of a Cox process, a simple independent thinning technique is proposed. In both cases, the thinning results in a Poisson process if and only if the true Papangelou conditional intensity is used, and...

  13. Thinning spatial point processes into Poisson processes

    DEFF Research Database (Denmark)

    Møller, Jesper; Schoenberg, Frederic Paik

    , and where one simulates backwards and forwards in order to obtain the thinned process. In the case of a Cox process, a simple independent thinning technique is proposed. In both cases, the thinning results in a Poisson process if and only if the true Papangelou conditional intensity is used, and thus can...

  14. Ultra-thin chip technology and applications

    CERN Document Server

    2010-01-01

    Ultra-thin chips are the "smart skin" of a conventional silicon chip. This book shows how very thin and flexible chips can be fabricated and used in many new applications in microelectronics, microsystems, biomedical and other fields. It provides a comprehensive reference to the fabrication technology, post processing, characterization and the applications of ultra-thin chips.

  15. New multiferroics BiFe{sub 1−2x}Al{sub x}Mn{sub x}O{sub 3} nanoparticles: Synthesis and evaluation of various structural, physical, electrical, dielectric and magnetic parameters

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Bashir [Institute of Chemical Sciences, Bahauddin Zakariya University, Multan 60800 (Pakistan); Mahmood, Azhar [Department of Chemistry, The Islamia University, Bahawalpur (Pakistan); Ashiq, Muhammad Naeem, E-mail: naeembzu@bzu.edu.pk [Institute of Chemical Sciences, Bahauddin Zakariya University, Multan 60800 (Pakistan); Malana, Muhammad Aslam; Najam-Ul-Haq, Muhammad; Ehsan, Muhammad Fahad [Institute of Chemical Sciences, Bahauddin Zakariya University, Multan 60800 (Pakistan); Warsi, Muhammad Farooq [Department of Chemistry, The Islamia University, Bahawalpur (Pakistan); Shakir, Imran, E-mail: mshakir@ksu.edu.sa [Deanship of scientific research, College of Engineering, King Saud University, PO Box 800, Riyadh 11421 (Saudi Arabia); BK 21 Physics Research Division, Department of Energy Science, Institute of Basic Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2014-03-25

    Graphical abstract: Nanostructures multiferroic BiFeO{sub 3} and its derivatives BiFe{sub 1−2x}Al{sub x}Mn{sub x}O{sub 3} in the range of 30–50 nm were fabricated by wet chemical route exhibited very high coercivity values and relatively small values of saturation magnetization and retentivity. -- Highlights: • New nanostructured derivatives of BiFeO{sub 3} were prepared by cheap method. • The rhombohedral structures of BiFe{sub 1−2x}Al{sub x}Mn{sub x}O{sub 3} were established. • The electrical resistivity was increased from 8 × 10{sup 8} to 48 × 10{sup 8} ohm cm. • The magnetic properties of the materials also enhanced by the substituents. -- Abstract: Nanostructures multiferroic BiFeO{sub 3} and its derivatives BiFe{sub 1−2x}Al{sub x}Mn{sub x}O{sub 3} are synthesized by a simple co-precipitation route. FTIR and XRD data confirms the rhombohedral structure and crystallite size is found in the range of 30–50 nm. The surface morphology change from round shaped particles to sheets form. The electrical resistivity is increased while the dielectric parameters decreased with the substituents. The BiFeO{sub 3} shows week ferromagnetic behavior and have high coercivity (Hc = 2590.3 G). The coercivity decreased from 2.59 × 10{sup 3} to 0. 211 × 10{sup 3} G with the increase in Al–Mn contents, while the saturation magnetization is found to increase from 0.030 to 0.056 emu g{sup −1} up to x = 0.3 and then decreased. The measured electrical, dielectric and magnetic parameters suggest that these materials can be utilized for fabricating the nano-devices working at very high frequencies as well as in data storage electronics devices.

  16. Magnetoelectric properties of multiferroic composites (1−x)ErMnO{sub 3}–xY{sub 3}Fe{sub 5}O{sub 12} at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Raneesh, B. [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, Kerala 686 560 (India); International and Inter University Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala 686 560 (India); Soumya, H.; Philip, J. [Sophisticated Test and Instrumentation Centre, Cochin University of Science and Technology, Cochin 682 022 (India); Thomas, S. [International and Inter University Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala 686 560 (India); Nandakumar, K., E-mail: nkkalarikkal@mgu.ac.in [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, Kerala 686 560 (India); International and Inter University Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala 686 560 (India)

    2014-10-25

    Highlights: • (1−x)ErMnO{sub 3}–xY{sub 3}Fe{sub 5}O{sub 12} (0 ⩽ x ⩽ 1) composites show room temperature ME coupling. • Magnetic properties of the samples measured as a function of YIG concentration show soft magnetic behavior. • Strong ME coupling is demonstrated in the composite 0.5RMnO{sub 3}–0.5YIG. • Phonon transport through these composites is effectively suppressed with YIG concentration. - Abstract: We report multiferroic behavior of the composites (1−x)ErMnO{sub 3}–xY{sub 3}Fe{sub 5}O{sub 12} (0 ⩽ x ⩽ 1) with spin–charge coupling at room temperature. These composites have been synthesized by sol–gel technique followed by solid-state reaction. Crystalline phases and microstructures of the composites are examined using X-ray diffraction (XRD) and transmission electron microscope (TEM) techniques. The XRD results indicate that the composites consist of both hexagonal ErMnO{sub 3} and cubic Y{sub 3}Fe{sub 5}O{sub 12} (YIG) phases. Dielectric constant decreases with increase in YIG concentration. Magnetic properties of the composite samples measured as a function of YIG concentration show soft magnetic behavior, with magnetization increasing with increasing YIG content. Strong magnetoelectric (ME) coupling is demonstrated in the composite 0.5ErMnO{sub 3}–0.5YIG by a dynamic lock-in amplifier set up. Thermal measurements using photopyroelectric technique indicate that thermal conductivity decreases with increase in YIG content or phonon transport through these composites is effectively suppressed with YIG concentration. These results provide data and criteria for the design and fabrication of potential devices based on this room temperature multiferroic material.

  17. Fundamentals of thin solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Yablonovitch, E. [Univ. of California, Los Angeles, CA (United States)

    1995-08-01

    It is now widely recognized that thin solar cells can present certain advantages for performance and cost. This is particularly the case when light trapping in the semiconductor film is incorporated, as compensation for the diminished single path thickness of the solar cell. In a solar cell thinner than a minority carrier diffusion length, the current collection is of course very easy. More importantly the concentration of an equivalent number of carriers in a thinner volume results in a higher Free Energy, or open circuit voltage. This extra Free Energy may be regarded as due to the concentration factor, just as it would be for photons, electrons, or for any chemical species. The final advantage of a thin solar cell is in the diminished material usage, a factor of considerable importance when we consider the material cost of the high quality semiconductors which we hope to employ.

  18. Thin films of soft matter

    CERN Document Server

    Kalliadasis, Serafim

    2007-01-01

    A detailed overview and comprehensive analysis of the main theoretical and experimental advances on free surface thin film and jet flows of soft matter is given. At the theoretical front the book outlines the basic equations and boundary conditions and the derivation of low-dimensional models for the evolution of the free surface. Such models include long-wave expansions and equations of the boundary layer type and are analyzed via linear stability analysis, weakly nonlinear theories and strongly nonlinear analysis including construction of stationary periodic and solitary wave and similarity solutions. At the experimental front a variety of very recent experimental developments is outlined and the link between theory and experiments is illustrated. Such experiments include spreading drops and bubbles, imbibitions, singularity formation at interfaces and experimental characterization of thin films using atomic force microscopy, ellipsometry and contact angle measurements and analysis of patterns using Minkows...

  19. Phase Coarsening in Thin Films

    Science.gov (United States)

    Wang, K. G.; Glicksman, M. E.

    2015-08-01

    Phase coarsening (Ostwald ripening) phenomena are ubiquitous in materials growth processes such as thin film formation. The classical theory explaining late-stage phase coarsening phenomena was developed by Lifshitz and Slyozov, and by Wagner in the 1960s. Their theory is valid only for a vanishing volume fraction of the second phase in three dimensions. However, phase coarsening in two-dimensional systems is qualitatively different from that in three dimensions. In this paper, the many-body concept of screening length is reviewed, from which we derive the growth law for a `screened' phase island, and develop diffusion screening theory for phase coarsening in thin films. The coarsening rate constant, maximum size of phase islands in films, and their size distribution function will be derived from diffusion screening theory. A critical comparison will be provided of prior coarsening concepts and improvements derived from screening approaches.

  20. Polycrystalline thin films : A review

    Energy Technology Data Exchange (ETDEWEB)

    Valvoda, V. [Charles Univ., Prague (Czech Republic). Faculty of Mathematics and Physics

    1996-09-01

    Polycrystalline thin films can be described in terms of grain morphology and in terms of their packing by the Thornton`s zone model as a function of temperature of deposition and as a function of energy of deposited atoms. Grain size and preferred grain orientation (texture) can be determined by X-ray diffraction (XRD) methods. A review of XRD analytical methods of texture analysis is given with main attention paid to simple empirical functions used for texture description and for structure analysis by joint texture refinement. To illustrate the methods of detailed structure analysis of thin polycrystalline films, examples of multilayers are used with the aim to show experiments and data evaluation to determine layer thickness, periodicity, interface roughness, lattice spacing, strain and the size of diffraction coherent volumes. The methods of low angle and high angle XRD are described and discussed with respect to their complementary information content.

  1. [Ultra-thin transnasal esophagogastroduodenoscopy].

    Science.gov (United States)

    Kawai, Takashi; Yamamoto, Kei; Fukuzawa, Mari; Sakai, Yoshihiro; Moriyasu, Fuminori

    2010-07-01

    It is reported that ultra-thin transnasal esophagogastroduodenoscopy (TN-EGD) reduces pharyngeal discomfort and is more tolerable for the patients. Ultra-thin transnasal endoscopy has been reported as inferior to transoral conventional EGD (TO-EGD) in terms of image quality, suction, air insufflation and lens washing, due to the smaller endoscope caliber. TN-EGD should be conducted slowly, with short distance observation, and also with image-enhanced endoscopy. With reference to image-enhanced endoscopy, chromoendoscopy method (indigocarmine) is suitable for gastric neoplasm, on the other hand optical digital method (NBI) and digital method (i-scan, FICE) is suitable for esophageal neoplasm. TN-EGD is applied in various gastrointestinal (GI) procedures such as percutaneous endoscopic gastrostomy, nasoenteric feeding tube placement, endoscopic retrograde cholangiopancreaticography with nasobiliary drainage, long intestinal tube placement in small bowel obstruction, esophageal manometry. PMID:20662204

  2. Ultimately Thin Metasurface Wave Plates

    CERN Document Server

    Keene, David; 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 shown to not be disrupted by non-locality and can be applied to the design of ultrathin wave plates, Pancharatnam-Berry phase optical elements and plasmon-carrying optical torque wrench devices.

  3. Fat and Thin Fisher Zeroes

    CERN Document Server

    Janke, W; Stathakopoulos, M

    2002-01-01

    We show that it is possible to determine the locus of Fisher zeroes in the thermodynamic limit for the Ising model on planar (``fat'') phi4 random graphs and their dual quadrangulations by matching up the real part of the high- and low-temperature branches of the expression for the free energy. Similar methods work for the mean-field model on generic, ``thin'' graphs. Series expansions are very easy to obtain for such random graph Ising models.

  4. Nanotemplated lead telluride thin films

    OpenAIRE

    Li, Xiaohong; Nandhakumar, Iris S.; Attard, George S.; Markham, Matthew L.; Smith, David C.; Baumberg, Jeremy J.

    2009-01-01

    Direct lyotropic liquid crystalline templating has been successfully applied to produce nanostructured IV–VI semiconductor PbTe thin films by electrodeposition both on gold and n-type (100) silicon substrates. The PbTe films were characterized by transmission electron microscopy, X-ray diffraction and polarized optical microscopy and the results show that the films have a regular hexagonal nanoarchitecture with a high crystalline rock salt structure and exhibit strong birefringenc...

  5. Organic thin-film photovoltaics

    OpenAIRE

    Liu, Miaoyin

    2010-01-01

    Zusammenfassung Zur Verbesserung der Leistungsumwandlung in organischen Solarzellen sind neue Materialien von zentraler Bedeutung, die sämtliche Erfordernisse für organische Photovoltaik-Elemente erfüllen. In der vorliegenden Arbeit „Organic thin-film photovoltaics“ wurden im Hinblick auf ein besseres Verständnis der Zusammenhänge zwischen molekularer Struktur und der Leistungsfähigkeit neue Materialien in „bulk-heterojunction“ Solarzellen und in Festphasen-Farbstoffsensibilisierten ...

  6. Thin functional conducting polymer films

    OpenAIRE

    Tian, S.

    2005-01-01

    In the present study, thin functional conducting polyaniline (PANI) films, either doped or undoped, patterned or unpatterned, were prepared by different approaches. The properties of the obtained PANI films were investigated in detail by a combination of electrochemistry with several other techniques, such as SPR, QCM, SPFS, diffraction, etc. The sensing applications (especially biosensing applications) of the prepared PANI films were explored. Firstly, the pure PANI films were prepar...

  7. Thin films and froth flotation

    International Nuclear Information System (INIS)

    The properties of thin, aqueous films on solid surfaces and their central role in the froth flotation process are discussed. The stability of these films can generally be described in terms of electrostatic and van der Waals forces. Significant experimental and theoretical advances are required in many areas (e.g. short range forces, film drainage) before a clear picture of the collision of, adhesion between and detachment of bubbles and particles will emerge. (orig.)

  8. Microscopic mechanistic study on the multiferroic of R2CoMnO6/La2CoMnO6 (R = Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm) by chemical and hydrostatic pressures: a first-principles calculation.

    Science.gov (United States)

    Meng, Junling; Liu, Xiaojuan; Hao, Xianfeng; Zhang, Lifang; Yao, Fen; Meng, Jian; Zhang, Hongjie

    2016-09-14

    A specific class of multiferroic superlattices R2CoMnO6/La2CoMnO6 (R = Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm), which displayed observable electric polarizations and considerable magnetization, were investigated based on density functional theory. The multiferroic behavior was induced by both of the a(-)a(-)c(+) Glazer rotation patterns of BO6 (CoO6 and MnO6) octahedra and ferromagnetic coupling in the magnetic ordered superlattices. In addition, the ferroelectric and ferromagnetic properties of R2CoMnO6/La2CoMnO6 superlattices can be tuned by chemical pressure and hydrostatic pressure, with the former being more effective in tuning magnetoelectric properties than the latter. For chemical pressure, the incorporation of lanthanide ions promoted an increase of BO6 octahedral tilting, reflected by the sharp decrease of Co-O3-Mn bond angles in the R-layer along the c axis. By contrast, the hydrostatic pressure acts on all three directions of the superlattice so that the change in Co-O-Mn bond angles is relatively small, therefore the octahedral distortion is much smaller than that caused by chemical pressure. Consequently, the electric polarization and magnetization changed more slowly. Our first-principles simulations proposed a series of rational multiferroic superlattices with tunable ferromagnetism and ferroelectricity by chemical and hydrostatic pressures, with expectation to be applied as novel spintronic materials. PMID:27506617

  9. New thin materials for electronics.

    Energy Technology Data Exchange (ETDEWEB)

    Schwartzberg, Adam

    2012-02-01

    The work described in this report is from an Early Career LDRD to develop and investigate novel thin film organic conductors with drastically improved electronic properties over the current state of the art. In collaboration with the Molecular Foundry at Lawrence Berkeley National Laboratory a Langmuir-Blodgett trough (LB) was built from scavenged parts and added to a scanning Raman microscope at LBNL. First order thin peptoid film samples were fabricated for testing Raman and photoluminescence imagining techniques. Tests showed that a single peptoid sheet can be successfully imaged using confocal Raman spectroscopy and a peptoid sheet can be successfully imaged using near-field photoluminescence at a resolution less than 70 nm. These results have helped position Sandia for advances in this area of MOF film creation. In collaboration with the Molecular Foundry at Lawrence Berkeley National Laboratory, a Langmuir-Blodgett trough (LB) was built and added to a scanning Raman microscope at LBNL. Thin peptoid film samples were fabricated for testing Raman and photoluminescence imagining techniques. Tests showed that a single peptoid sheet can be successfully imaged using confocal Raman spectroscopy, and a peptoid sheet can be successfully imaged using near-field photoluminescence at a resolution less than 70 nm. These results have positioned Sandia for advance in this area of MOF film creation. The interactions with LBNL also led to award of two user projects at the Molecular Foundry at LBNL led by current Sandia staff and the appointment of a current Sandia staff to the Molecular Foundry User Executive Committee.

  10. Minerals deposited as thin films

    International Nuclear Information System (INIS)

    Free matrix effects are due to thin film deposits. Thus, it was decided to investigate this technique as a possibility to use pure oxide of the desired element, extrapolating its concentration from analytical curves made with avoiding, at the same time, mathematical corrections. The proposed method was employed to determine iron and titanium concentrations in geological samples. The range studied was 0.1-5%m/m for titanium and 5-20%m/m for iron. For both elements the reproducibility was about 7% and differences between this method and other chemical determinations were 15% for titanium and 7% for iron. (Author)

  11. Preparation of thin vyns films

    International Nuclear Information System (INIS)

    The fabrication of thin films of VYNS resin (copolymer of chloride and vinyl acetate) of superficial density from 3 to 50 μg/cm2 with solutions in cyclohexanone is presented. Study and discussion of some properties compared with formvar film (polyvinyl formals). It appears that both can be used as source supports but formvar films are prepared more easily and more quickly, in addition they withstand higher temperatures. The main quality of VYNS is that they can be easily separated even several days after their preparation

  12. Mixing in shear thinning fluids

    Directory of Open Access Journals (Sweden)

    H. Ameur

    2012-06-01

    Full Text Available In the present study, a CFD characterization of the flow generated by curved-blade impellers in a cylindrical unbaffled vessel was carried out. The tank diameter was 300 mm, with a flat bottom. The liquid height was equal to the vessel diameter. The fluids simulated have a shear thinning behavior. Analyses concern the effect of the impeller speed, the fluid rheology and the number of impeller blades on the induced flow patterns and the power consumption. The predictions were compared with literature data and a satisfactory agreement was found.

  13. Interactions in thin aqueous films

    OpenAIRE

    Hänni-Ciunel, Katarzyna

    2006-01-01

    In der Arbeit werden die Wechselwirkungen in dünnen flüssigen Filmen untersucht und modifiziert. Schaum- (gas/flüssig/gas) und Benetzungsfilme (gas/flüssig/fest) werden mittels Thin Film Pressure Balance (TFPB) untersucht. Die Apparatur wurde im Rahmen der Arbeit für die Studien an asymmetrischen Filmen aufgebaut und modifiziert. Die Ladungen an den Filmgrenzflächen werden gezielt modifiziert. Die Adsoprtion von Tensiden bestimmt die Oberflächenladung an der gas/flüssig Grenzfläche. Die Oberf...

  14. Nonlinear strain gradient elastic thin shallow shells

    OpenAIRE

    Lazopoulos, K.A.

    2011-01-01

    Abstract The governing equilibrium equations for strain gradient elastic thin shallow shells are derived, considering non-linear strains and linear constitutive strain gradient elastic relations. Adopting Kirchhoff's theory of thin shallow structures, the equilibrium equations, along with the boundary conditions, are formulated through a variational procedure. It turns out that new terms are introduced, indicating the importance of the cross-section area in bending of thin plates. ...

  15. Flexible Tactile Sensor Using Polyurethane Thin Film

    OpenAIRE

    Seiji Aoyagi; Tomokazu Takahashi; Masato Suzuki

    2012-01-01

    A novel capacitive tactile sensor using a polyurethane thin film is proposed in this paper. In previous studies, capacitive tactile sensors generally had an air gap between two electrodes in order to enhance the sensitivity. In this study, there is only polyurethane thin film and no air gap between the electrodes. The sensitivity of this sensor is higher than the previous capacitive tactile sensors because the polyurethane is a fairly flexible elastomer and the film is very thin (about 1 µm)....

  16. Thin-film crystalline silicon solar cells

    CERN Document Server

    Brendel, Rolf

    2011-01-01

    This introduction to the physics of silicon solar cells focuses on thin cells, while reviewing and discussing the current status of the important technology. An analysis of the spectral quantum efficiency of thin solar cells is given as well as a full set of analytical models. This is the first comprehensive treatment of light trapping techniques for the enhancement of the optical absorption in thin silicon films.

  17. Applications of thin coatings in automotive industry

    OpenAIRE

    P. Louda

    2007-01-01

    Purpose: Use of thin coatings in automotive industry give economic and ecological savings. This is evoke by reducing of weight of used construction elements and currently by increasing of their service life and with that connected elevating of nanomaterials manufacture qualities.Design/methodology/approach: In the paper was disscussed the possibility of applications of thin coating in automotive industry.Findings: The paper shows the examples of thin coatings application in automotive industr...

  18. Thin films for emerging applications v.16

    CERN Document Server

    Francombe, Maurice H

    1992-01-01

    Following in the long-standing tradition of excellence established by this serial, this volume provides a focused look at contemporary applications. High Tc superconducting thin films are discussed in terms of ion beam and sputtering deposition, vacuum evaporation, laser ablation, MOCVD, and other deposition processes in addition to their ultimate applications. Detailed treatment is also given to permanent magnet thin films, lateral diffusion and electromigration in metallic thin films, and fracture and cracking phenomena in thin films adhering to high-elongation substrates.

  19. Preparation of thin nuclear targets

    International Nuclear Information System (INIS)

    Thin film backings, sources and targets are needed for many applications in low energy nuclear physics and nuclear chemistry experiments. A survey of techniques used in the preparation of nuclear targets is first briefly discussed. These are classified as chemical, mechanical and physical preparations. Vacuum evaporation, being the most generally used technique, is discussed in detail. It is highly desirable to monitor the film thickness and control the deposition rate during evaporation and to measure the final target thickness after deposition has concluded. The relative merits of various thickness measuring techniques are described. Stages in the fabrication and mounting of self-supporting foils are described in detail, with emphasis given to the preparation of thin self-supporting carbon foils used as target backings and stripper foils. Various target backings, and the merits of the more generally used release agents are described in detail. The preparations of more difficult elemental targets are discussed, and a comprehensive list of the common targets is presented

  20. Structural, electrical and dielectric properties of La{sub 0.7}Sr{sub 0.3}MnO{sub 3}–ErMnO{sub 3} multiferroic composites

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, S.K., E-mail: saniitkgp2007@gmail.com [Department of Physics, National Institute of Technology Agartala, Tripura 799055 (India); Dey, P., E-mail: pujaiitkgp2007@gmail.com [Department of Physics, National Institute of Technology Agartala, Tripura 799055 (India); Nath, T.K. [Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721302 (India)

    2014-02-15

    A different kind of multiferroics with composite character has been studied. Detailed study on electrical and dielectric properties of structurally characterized multiferroic composites xLa{sub 0.7}Sr{sub 0.3}MnO{sub 3}–(1 − x)ErMnO{sub 3} (where, x = 0, 0.1, 0.15, 0.2, 1), prepared through chemical ‘pyrophoric reaction’ technique, have been presented. Average particle size of the composites is found to be in nanometric region. Both structural and magnetic studies confirm almost complete immiscibility within the mixture of two compounds of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} and ErMnO{sub 3} having nearly identical chemical formula. Impedance value is found to be decreased with increasing La{sub 0.7}Sr{sub 0.3}MnO{sub 3} content in the composites that can be attributed to the improved electrical connectivity in the sample. Dielectric study reveals that pure ErMnO{sub 3}, 0.1La{sub 0.7}Sr{sub 0.3}MnO{sub 3}–0.9ErMnO{sub 3} and 0.15La{sub 0.7}Sr{sub 0.3}MnO{sub 3}–0.85ErMnO{sub 3} composites exhibiting ferroelectric relaxor behavior, whereas 0.2La{sub 0.7}Sr{sub 0.3}MnO{sub 3}–0.8ErMnO{sub 3} composite is found to be strongly diffusive ferroelectric sample. Appearance of a distinct hump in dielectric constant of 0.1La{sub 0.7}Sr{sub 0.3}MnO{sub 3}–0.9ErMnO{sub 3} composite at the vicinity of para-ferromagnetic transition temperature may be due to some sort of magneto-electric coupling in these composites.

  1. Thin CVD Coating Protects Titanium Aluminide Alloys

    Science.gov (United States)

    Clark, Ronald; Wallace, Terryl; Cunnington, George; Robinson, John

    1994-01-01

    Feasibility of using very thin CVD coatings to provide both protection against oxidation and surfaces of low catalytic activity for thin metallic heat-shield materials demonstrated. Use of aluminum in compositions increases emittances of coatings and reduces transport of oxygen through coatings to substrates. Coatings light in weight and applied to foil-gauge materials with minimum weight penalties.

  2. Thin disk lasers: history and prospects

    Science.gov (United States)

    Speiser, Jochen

    2016-04-01

    During the early 1990s, collaboration between the German Aerospace Center and the University of Stuttgart started to work on the Thin Disk concept. The core idea behind the thin disk design is the use of a thin, disk-shaped active medium that is cooled through one of the flat faces of the disk. This ensures a large surface-to-volume ratio and therefore provides very efficient thermal management. Today, the thin disk concept is used in various commercial lasers - ranging from compact, efficient low power systems to multi-kW lasers, including cw lasers and also pulsed (femtosecond to nanosecond) oscillators and amplifiers. The whole development of the Thin Disk laser was and will be accompanied by numerical modeling and optimization of the thermal and thermo-mechanic behavior of the disk and also the heat sink structure, mostly based on finite element models. For further increasing the energy and efficiency of pulsed Thin Disk lasers, the effects of amplified spontaneous emission (ASE) are a core issue. Actual efforts are oriented towards short pulse and ultra-short pulse amplifiers with (multi-)kW average power or Joule-class Thin Disk amplifiers, but also on new designs for cw thin disk MOPA designs.

  3. Thin Shell Wormhole in Heterotic String Theory

    OpenAIRE

    Rahaman, F.; Kalam, M.; S. Chakraborti

    2006-01-01

    Using 'Cut and Paste' technique, we develop a thin shell wormhole in heterotic string theory. We determine the surface stresses, which are localized in the shell, by using Darmois-Israel formalism. The linearized stability of this thin wormhole is also analyzed.

  4. Delamination of Compressed Thin Layers at Corners

    DEFF Research Database (Denmark)

    Sørensen, Kim Dalsten; Jensen, Henrik Myhre; Clausen, Johan

    2008-01-01

    An analysis of delamination for a thin elastic layer under compression, attached to a substrate at a corner is carried out. The analysis is performed by combining results from interface fracture mechanics and the theory of thin shells. In contrast with earlier results for delamination on a flat...

  5. Delamination of Compressed thin Layers at Corners

    DEFF Research Database (Denmark)

    Clausen, Johan; Jensen, Henrik Myhre; Sørensen, Kim Dalsten

    2008-01-01

    An analysis of delamination for a thin elastic film, attached to a substrate with a corner, is carried out. The film is in compression and the analysis is performed by combining results from fracture mechanics and the theory of thin shells. The results show a very strong dependency of the angle...

  6. Discontinious Galerkin formulations for thin bending problems

    NARCIS (Netherlands)

    Nguyen, T.D.

    2008-01-01

    A structural thin bending problem is essentially associated with a fourth-order partial differential equation. Within the finite element framework, the numerical solution of thin bending problems demands the use of C^1 continuous shape functions. Elements using these functions are challenging and di

  7. Christhin: Quantitative Analysis of Thin Layer Chromatography

    CERN Document Server

    Barchiesi, Maximiliano; Renaudo, Carlos; Rossi, Pablo; Pramparo, María de Carmen; Nepote, Valeria; Grosso, Nelson Ruben; Gayol, María Fernanda

    2012-01-01

    Manual for Christhin 0.1.36 Christhin (Chromatography Riser Thin) is software developed for the quantitative analysis of data obtained from thin-layer chromatographic techniques (TLC). Once installed on your computer, the program is very easy to use, and provides data quickly and accurately. This manual describes the program, and reading should be enough to use it properly.

  8. Neutron activation analysis of thin orange pottery

    Energy Technology Data Exchange (ETDEWEB)

    Harbottle, G; Sayre, E V; Abascal, R

    1976-01-01

    The evidence thus far obtained supports the idea of ''Thin Orange'' ware, typical of classic Teotihuacan culture, easily identifiable petrographically or chemically, not necessarily made at Teotihuacan itself but widely traded, and ''thin, orange'' pottery, fabricated in many other places, and perhaps at other times as well.

  9. Bending of a thin flexible plate

    Energy Technology Data Exchange (ETDEWEB)

    Pobedria, B.E.

    1990-12-01

    A system of equations is derived which describes the one-dimensional deformation of thin shells. The analysis does not impose any constraints on the relative elongation and deflections. As an example, a solution is presented for the problem of the bending of a thin plate under uniform pressure.

  10. Plasma polymerized hydrogel thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tamirisa, Prabhakar A. [School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Koskinen, Jere [Institute of Paper Science and Technology, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Hess, Dennis W. [School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)]. E-mail: dennis.hess@chbe.gatech.edu

    2006-12-05

    Plasma polymerization was used to produce thermoresponsive hydrogel films of N-isopropylacrylamide (NIPAAm) in a single deposition step. Solvent free processing to produce laterally confined intelligent hydrogel films offers the potential for high volume production of micro-sensors/actuators. Through variation of reactor conditions such as deposition pressure and substrate temperature, it is possible to tailor and control chemical properties of the films such as crosslink density and thus swelling. Fabrication of hydrogel thin films with adequate crosslinks is critical to ensuring adhesion to substrates and stability in aqueous environments. Chemical bonding structures in plasma polymerized NIPAAm were studied using Fourier transform infrared spectroscopy and the thermoresponsive nature of plasma polymerized NIPAAm was confirmed through contact angle goniometry. A reversible temperature dependent contact angle change was observed.

  11. BDS thin film damage competition

    Energy Technology Data Exchange (ETDEWEB)

    Stolz, C J; Thomas, M D; Griffin, A J

    2008-10-24

    A laser damage competition was held at the 2008 Boulder Damage Symposium in order to determine the current status of thin film laser resistance within the private, academic, and government sectors. This damage competition allows a direct comparison of the current state-of-the-art of high laser resistance coatings since they are all tested using the same damage test setup and the same protocol. A normal incidence high reflector multilayer coating was selected at a wavelength of 1064 nm. The substrates were provided by the submitters. A double blind test assured sample and submitter anonymity so only a summary of the results are presented here. In addition to the laser resistance results, details of deposition processes, coating materials, and layer count will also be shared.

  12. Thin-film optical shutter

    Science.gov (United States)

    Matlow, S. L.

    1981-02-01

    The ideal solution to the excessive solar gain problem is an optical shutter, a device which switches from being highly transmissive to solar radiation to being highly reflective to solar radiation when a critical temperature is reached in the enclosure. The switching occurs because one or more materials in the device undergo a phase transition at the critical temperature. A specific embodiment of macroconjugated macromolecules, the poly (p-phenylene)'s, was chosen as the one most likely to meet all of the requirements of the thin film optical shutter project (TFOS). The reason for this choice is explored. In order to be able to make meaningful calculations of the thermodynamic and optical properties of the poly (p-phenylene)'s a quantum mechanical method, the equilibrium bond length (EBL) theory, was developed. Some results of EBL theory are included.

  13. Thin film bioreactors in space

    Science.gov (United States)

    Hughes-Fulford, M.; Scheld, H. W.

    1989-01-01

    Studies from the Skylab, SL-3 and D-1 missions have demonstrated that biological organisms grown in microgravity have changes in basic cellular functions such as DNA, mRNA and protein synthesis, cytoskeleton synthesis, glucose utilization, and cellular differentiation. Since microgravity could affect prokaryotic and eukaryotic cells at a subcellular and molecular level, space offers an opportunity to learn more about basic biological systems with one inmportant variable removed. The thin film bioreactor will facilitate the handling of fluids in microgravity, under constant temperature and will allow multiple samples of cells to be grown with variable conditions. Studies on cell cultures grown in microgravity would make it possible to identify and quantify changes in basic biological function in microgravity which are needed to develop new applications of orbital research and future biotechnology.

  14. TEC – Thin Environmental Cladding

    Directory of Open Access Journals (Sweden)

    Alan Tomasi

    2015-05-01

    Full Text Available Permasteelisa Group developed with Fiberline Composites a new curtain wall system (Thin Environmental Cladding or TEC, making use of pultruded GFRP (Glass Fiber Reinforced Polymer material instead of traditional aluminum. Main advantages using GFRP instead of aluminum are the increased thermal performance and the limited environmental impact. Selling point of the selected GFRP resin is the light transmission, which results in pultruded profiles that allow the visible light to pass through them, creating great aesthetical effects. However, GFRP components present also weaknesses, such as high acoustic transmittance (due to the reduced weight and anisotropy of the material, low stiffness if compared with aluminum (resulting in higher facade deflection and sensible fire behavior (as combustible material. This paper will describe the design of the TEC-facade, highlighting the functional role of glass within the facade concept with regards to its acoustic, structural, aesthetics and fire behavior.

  15. Shielding superconductors with thin films

    CERN Document Server

    Posen, Sam; Catelani, Gianluigi; Liepe, Matthias U; Sethna, James P

    2015-01-01

    Determining the optimal arrangement of superconducting layers to withstand large amplitude AC magnetic fields is important for certain applications such as superconducting radiofrequency cavities. In this paper, we evaluate the shielding potential of the superconducting film/insulating film/superconductor (SIS') structure, a configuration that could provide benefits in screening large AC magnetic fields. After establishing that for high frequency magnetic fields, flux penetration must be avoided, the superheating field of the structure is calculated in the London limit both numerically and, for thin films, analytically. For intermediate film thicknesses and realistic material parameters we also solve numerically the Ginzburg-Landau equations. It is shown that a small enhancement of the superheating field is possible, on the order of a few percent, for the SIS' structure relative to a bulk superconductor of the film material, if the materials and thicknesses are chosen appropriately.

  16. HTML thin client and transactions

    CERN Document Server

    Touchette, J F

    1999-01-01

    When writing applications for thin clients such as Web browsers, you face several challenges that do not exist with fat-client applications written in Visual Basic, Delphi, or Java. For one thing, your development tools do not include facilities for automatically building reliable, nonrepeatable transactions into applications. Consequently, you must devise your own techniques to prevent users from transmitting duplicate transactions. The author explains how to implement reliable, nonrepeatable transactions using a technique that is applicable to any Java Server Development Kit based architecture. Although the examples presented are based on the IBM WebSphere 2.1 Application Server, they do not make use of any IBM WebSphere extensions. In short, the concepts presented here can be implemented in Perl CGI and ASP scripts, and the sample code has been tested with JDK 1.1.6 and 1.2. (0 refs).

  17. Curved thin shell buckling behaviour

    Directory of Open Access Journals (Sweden)

    G. Forasassi

    2007-08-01

    Full Text Available Purpose: The aim of the paper is to evaluate buckling instabilities behaviour of long curved thin shell. Both initially straight and curved tubes are investigated with numerical and experimental assessment methods, in the context of NPP applications with an illustrative example for IRIS LWR integrated Steam Generator (SG tubes.Design/methodology/approach: In this study structural buckling response tube with combination effects of geometric imperfections as well as initially bent shape under external pressure load are investigated using a non linear finite element (MSC.MARC FEM code formulation analysis. Moreover results are presented, extending the findings of previous research activity works, carried out at Pisa University, on thin walled metal specimen.Findings: The experiments were conducted on Inconel 690 test specimen tube. The comparison between numerical and experimental results, for the same geometry and loading conditions, shows a good agreement between the elastic-plastic finite-element predictions and the experimental data.Research limitations/implications: The presented research results may be considered preliminary in the sense that it would be important to enlarge the statistical base of the results themselves, even if they are yet certainly meaningful to highlight the real problem, considering the relatively large variability of the geometrical imperfections and bending instabilities also in high quality production tubes.Originality/value: From the point of view of the practical implication, besides the addressed problem general interest in industrial plant technology, it is worth to stress that straight and curved axis tubes are foreseen specifically in innovative nuclear reactors SG design.

  18. Thin liquid films dewetting and polymer flow

    CERN Document Server

    Blossey, Ralf

    2012-01-01

    This book is a treatise on the thermodynamic and dynamic properties of thin liquid films at solid surfaces and, in particular, their rupture instabilities. For the quantitative study of these phenomena, polymer thin films haven proven to be an invaluable experimental model system.   What is it that makes thin film instabilities special and interesting, warranting a whole book? There are several answers to this. Firstly, thin polymeric films have an important range of applications, and with the increase in the number of technologies available to produce and to study them, this range is likely to expand. An understanding of their instabilities is therefore of practical relevance for the design of such films.   Secondly, thin liquid films are an interdisciplinary research topic. Interdisciplinary research is surely not an end to itself, but in this case it leads to a fairly heterogeneous community of theoretical and experimental physicists, engineers, physical chemists, mathematicians and others working on the...

  19. Squirming through shear-thinning fluids

    CERN Document Server

    Datt, Charu; Elfring, Gwynn J; Pak, On Shun

    2015-01-01

    Many microorganisms find themselves immersed in fluids displaying non-Newtonian rheological properties such as viscoelasticity and shear-thinning viscosity. The effects of viscoelasticity on swimming at low Reynolds numbers have already received considerable attention, but much less is known about swimming in shear-thinning fluids. A general understanding of the fundamental question of how shear-thinning rheology influences swimming still remains elusive. To probe this question further, we study a spherical squirmer in a shear-thinning fluid using a combination of asymptotic analysis and numerical simulations. Shear-thinning rheology is found to affect a squirming swimmer in nontrivial and surprising ways; we predict and show instances of both faster and slower swimming depending on the surface actuation of the squirmer. We also illustrate that while a drag and thrust decomposition can provide insights into swimming in Newtonian fluids, extending this intuition to problems in complex media can prove problemat...

  20. Highly textured Sr, Nb co-doped BiFeO{sub 3} thin films grown on SrRuO{sub 3}/Si substrates by rf- sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Ostos, C. [Universidad Nacional Autonoma de Mexico, Instituto de Investigaciones en Materiales, AP 70360, Mexico D.F. 04510 (Mexico); Universidad Nacional Autonoma de Mexico, Centro de Nanociencias y Nanotecnologia, AP 14, Ensenada B.C. 22890 (Mexico); Raymond, O.; Siqueiros, J. M. [Universidad Nacional Autonoma de Mexico, Centro de Nanociencias y Nanotecnologia, AP 14, Ensenada B.C. 22890 (Mexico); Suarez-Almodovar, N. [Universidad de La Habana, Facultad de Fisica-IMRE, San Lazaro y L, 10400, Louisiana Habana (Cuba); Bueno-Baques, D. [Centro de Investigacion en Quimica Aplicada, Enrique Reyna 140, Saltillo, Coah. 25253 (Mexico); Mestres, L. [Universitat de Barcelona, Facultat de Quimica, Av. Diagonal 648, 08028, Barcelona (Spain)

    2011-07-15

    In this study, (011)-highly oriented Sr, Nb co-doped BiFeO{sub 3} (BFO) thin films were successfully grown on SrRuO{sub 3}/Si substrates by rf-magnetron sputtering. The presence of parasite magnetic phases was ruled out based on the high resolution x-ray diffraction data. BFO films exhibited a columnar-like grain growth with rms surface roughness values of {approx_equal}5.3 nm and average grain sizes of {approx_equal}65-70 nm for samples with different thicknesses. Remanent polarization values (2P{sub r}) of 54 {mu}C cm{sup -2} at room temperature were found for the BFO films with a ferroelectric behavior characteristic of an asymmetric device structure. Analysis of the leakage mechanisms for this structure in negative bias suggests Schottky injection and a dominant Poole-Frenkel trap-limited conduction at room temperature. Oxygen vacancies and Fe{sup 3+}/Fe{sup 2+} trap centers are consistent with the surface chemical bonding states analysis from x-ray photoelectron spectroscopy data. The (011)-BFO/SrRuO{sub 3}/Si film structure exhibits a strong magnetic interaction at the interface between the multiferroic film and the substrate layer where an enhanced ferromagnetic response at 5 K was observed. Zero-field cooled (ZFC) and field cooled (FC) magnetization curves of this film system revealed a possible spin glass behavior at spin freezing temperatures below 30 K depending on the BFO film thickness.