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Sample records for crystal fe films

  1. Reduction of crystallization temperature of the Nd-Fe-B thin films by Cu addition

    International Nuclear Information System (INIS)

    Ma Yungui; Yang Zheng; Matsumoto, M.; Morisako, A.; Takei, S.

    2004-01-01

    Nonmagnetic Cu element has been doped into the sputtered Nd-Fe-B thin films. It is found that the introduction of suitable amount of copper atoms could reduce the crystallization temperature of the 2:14:1 phase by near 100 deg. C, compared with that without Cu. For the 15 nm Nd 16 Fe 70.2 Cu 1.8 B 12 film deposited at 340 deg. C, perpendicular coercivity and remanent magnetization ratio of 350 kA/m and 0.96 have been successfully obtained. Cu addition would lead to the grain growth, but the average grain size in the films could be greatly decreased through lowering the deposition temperature. These results are compared with those found in the fabrication of FePtCu films

  2. Formation of SmFe5(0001) ordered alloy thin films on Cu(111) single-crystal underlayers

    International Nuclear Information System (INIS)

    Yabuhara, Osamu; Ohtake, Mitsuru; Nukaga, Yuri; Futamoto, Masaaki; Kirino, Fumiyoshi

    2010-01-01

    SmFe 5 (0001) single-crystal thin films are prepared by molecular beam epitaxy employing Cu(111) single-crystal underlayers on MgO(111) substrates. The Cu atoms diffuse into the Sm-Fe layer and substitute the Fe sites in SmFe 5 structure forming an alloy compound of Sm(Fe,Cu) 5 . The Sm(Fe,Cu) 5 film is more Cu enriched with increasing the substrate temperature. The Cu underlayer plays an important role in assisting the formation of the ordered phase.

  3. Formation of SmFe{sub 5}(0001) ordered alloy thin films on Cu(111) single-crystal underlayers

    Energy Technology Data Exchange (ETDEWEB)

    Yabuhara, Osamu; Ohtake, Mitsuru; Nukaga, Yuri; Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi, E-mail: yabuhara@futamoto.elect.chuo-u.ac.j [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan)

    2010-01-01

    SmFe{sub 5}(0001) single-crystal thin films are prepared by molecular beam epitaxy employing Cu(111) single-crystal underlayers on MgO(111) substrates. The Cu atoms diffuse into the Sm-Fe layer and substitute the Fe sites in SmFe{sub 5} structure forming an alloy compound of Sm(Fe,Cu){sub 5}. The Sm(Fe,Cu){sub 5} film is more Cu enriched with increasing the substrate temperature. The Cu underlayer plays an important role in assisting the formation of the ordered phase.

  4. Preparation and structural characterization of FeCo epitaxial thin films on insulating single-crystal substrates

    International Nuclear Information System (INIS)

    Nishiyama, Tsutomu; Ohtake, Mitsuru; Futamoto, Masaaki; Kirino, Fumiyoshi

    2010-01-01

    FeCo epitaxial films were prepared on MgO(111), SrTiO 3 (111), and Al 2 O 3 (0001) single-crystal substrates by ultrahigh vacuum molecular beam epitaxy. The effects of insulating substrate material on the film growth process and the structures were investigated. FeCo(110) bcc films grow on MgO substrates with two type domains, Nishiyama-Wassermann (NW) and Kurdjumov-Sachs (KS) relationships. On the contrary, FeCo films grown on SrTiO 3 and Al 2 O 3 substrates include FeCo(111) bcc crystal in addition to the FeCo(110) bcc crystals with NW and KS relationships. The FeCo(111) bcc crystal consists of two type domains whose orientations are rotated around the film normal by 180 deg. each other. The out-of-plane and the in-plane lattice spacings of FeCo(110) bcc and FeCo(111) bcc crystals formed on the insulating substrates are in agreement with those of the bulk Fe 50 Co 50 (at. %) crystal with small errors ranging between +0.2% and +0.4%, showing that the strains in the epitaxial films are very small.

  5. Microstructure and magnetic properties of FeCo epitaxial thin films grown on MgO single-crystal substrates

    International Nuclear Information System (INIS)

    Shikada, Kouhei; Ohtake, Mitsuru; Futamoto, Masaaki; Kirino, Fumiyoshi

    2009-01-01

    FeCo epitaxial films were prepared on MgO(100), MgO(110), and MgO(111) substrates by ultrahigh vacuum molecular beam epitaxy. FeCo thin films with (100), (211), and (110) planes parallel to the substrate surface grow on respective MgO substrates. FeCo/MgO interface structures are studied by high-resolution cross-sectional transmission electron microscopy and the epitaxial growth mechanism is discussed. Atomically sharp boundaries are recognized between the FeCo thin films and the MgO substrates where misfit dislocations are introduced in the FeCo thin films presumably to decrease the lattice misfits. Misfit dislocations are observed approximately every 9 and 1.4 nm in FeCo thin film at the FeCo/MgO(100) and the FeCo/MgO(110) interfaces, respectively. X-ray diffraction analysis indicates that the lattice spacing measured parallel to the single-crystal substrate surfaces are in agreement within 0.1% with those of the respective bulk values of Fe 50 Co 50 alloy crystal, showing that the FeCo film strain is very small. The magnetic anisotropies of these epitaxial films basically reflect the magnetocrystalline anisotropy of bulk FeCo alloy crystal

  6. Composition dependence of crystallization temperature and magnetic property of NdFeB thin films

    Energy Technology Data Exchange (ETDEWEB)

    Khoa, T.V. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of); International Training Institute for Materials Science (ITIMS), Hanoi University of Technology, 1 Dai Co Viet, Hanoi (Viet Nam); Ha, N.D. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of); Hong, S.M. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of); Jin, H.M. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of); Kim, G.W. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of); Hien, T.D. [International Training Institute for Materials Science (ITIMS), Hanoi University of Technology, 1 Dai Co Viet, Hanoi (Viet Nam); Tai, L.T. [International Training Institute for Materials Science (ITIMS), Hanoi University of Technology, 1 Dai Co Viet, Hanoi (Viet Nam); Duong, N.P. [International Training Institute for Materials Science (ITIMS), Hanoi University of Technology, 1 Dai Co Viet, Hanoi (Viet Nam); Lee, K.E. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of); Kim, C.G. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of); Kim, C.O. [Research Center for Advanced Magnetic Materials (ReCAMM), Chungnam National University, Daejon, 305-764 (Korea, Republic of)]. E-mail: magkim@cnu.ac.kr

    2006-09-15

    Si(100)/Mo(30nm)/Nd{sub x}Fe{sub 92-x}B{sub 8}(800nm)/Mo(30nm) (x=14, 20, 30) films are prepared by RF magnetron sputtering at room temperature. As-deposited films are amorphous materials. The crystallization temperature of the Nd{sub 2}Fe{sub 14}B phase decreases from 575deg. C to 500deg. C with increase of x from 14 to 20-30. The optimum annealing temperature with 30min annealing time is 650 deg. C, 625 deg. C and 600 deg. C for x=14, 20 and 30, respectively, and the x=20 film has the largest energy product of 100118MG.

  7. Transverse anisotropic magnetoresistance effects in pseudo-single-crystal γ′-Fe4N thin films

    Directory of Open Access Journals (Sweden)

    Kazuki Kabara

    2016-05-01

    Full Text Available Transverse anisotropic magnetoresistance (AMR effects, for which magnetization is rotated in an orthogonal plane to the current direction, were investigated at various temperatures, in order to clarify the structural transformation from a cubic to a tetragonal symmetry in a pseudo-single-crystal Fe4N film, which is predicted from the usual in-plane AMR measurements by the theory taking into account the spin-orbit interaction and crystal field splitting of 3d bands. According to a phenomenological theory of AMR, which derives only from the crystal symmetry, a cos 2θ component ( C 2 tr exists in transverse AMR curves for a tetragonal system but does not for a cubic system. In the Fe4N film, the C 2 tr shows a positive small value (0.12% from 300 K to 50 K. However, the C 2 t r increases to negative value below 50 K and reaches to -2% at 5 K. The drastic increasing of the C 2 tr demonstrates the structural transformation from a cubic to a tetragonal symmetry below 50 K in the Fe4N film. In addition, the out-of-plane and in-plane lattice constants (c and a were precisely determined with X-ray diffraction at room temperature using the Nelson-Riely function. As a result, the positive small C 2 t r above 50 K is attributed to a slightly distorted Fe4N lattice (c/a = 1.002.

  8. Crystallization and atomic diffusion behavior of high coercive Ta/Nd-Fe-B/Ta-based permanent magnetic thin film

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Na; Zhang, Xiao; You, Caiyin; Fu, Huarui [Xi' an University of Technology, School of Materials Science and Engineering, Xi' an (China); Shen, Qianlong [Logistics University of People' s Armed Police Force, Tianjin (China)

    2017-06-15

    A high coercivity of about 20.4 kOe was obtained through post-annealing the sputtered Ta/Nd-Fe-B/Ta-based permanent magnetic thin films. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analyses were performed to investigate the crystallization and atomic diffusion behaviors during post-annealing. The results show that the buffer and capping Ta layers prefered to intermix with Fe and B atoms, and Nd tends to be combined with O atoms. The preferred atomic combination caused the appearance of the soft magnetic phase of Fe-Ta-B, resulting in a kink of the second quadratic magnetic hysteresis loop. The preferred atomic diffusion and phase formation of the thin films were well explained in terms of the formation enthalpy of the various compounds. (orig.)

  9. Nucleation and growth of a BCC Fe phase deposited on a single crystal (001) Cu film

    International Nuclear Information System (INIS)

    Koike, J.

    1991-01-01

    As a thin film overlayer grows on a substrate with a different structure, the overlayer initially adopts the substrate structure and subsequently transforms to an equilibrium bulk structure. such a growth characteristic has been extensively studied in Fe/Cu bicrystals. An Fe overlayer grown on a Cu substrate is known to have the fcc structure up to a thickness of 2 nm, whereas a thicker Fe overlayer consists of submicrometer grains of the bcc-Cu has been reported in a relatively thick Fe film and was found to consist of the Nishiyama (N), Kurdjumov-Sacks (KS), or Pitsch (P), depending on the orientation of the substrate surface. However, previous studies have not explained how the bcc structure nucleates or how the observed submicrometer polycrystalline grains form. The paper provides an understanding of these two points. Transmission electron microscopy (TEM) was used to study Fe/Cu bicrystals as the Fe thickness was varied systematically. Analysis of moire fringes, which are caused by superposition of different structures, enabled us to determine the orientation relationship between the very thin Fe layer and the Cu substrate. We show that a single variant of the P orientation relationship, which accompanies atomic rearrangement parallel to the interface, predominates at the nucleation stage of the bcc structure. Nucleation of other variants of P, N, and KS occurs with increasing Fe thickness and causes the formation of the submicrometer bcc grains

  10. Ion backscattering, channeling and nuclear reaction analysis study of passive films formed on FeCrNi and FeCrNiMo (100) single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, C; Schmaus, D [Paris-7 Univ., 75 (France). Groupe de Physique des Solides de l' ENS; Elbiache, A; Marcus, P [Ecole Nationale Superieure de Chimie, 75 - Paris (France)

    1990-01-01

    The compositions of passive films formed on Fe-17Fr-13Ni (at. %) and Fe-18.5Cr-14Ni-1.5Mo (100) single crystals have been determined and the structure of the alloy under the film has been investigated. The alloys were passivated in 0.05M H{sub 2}SO{sub 4} at 250 mV/SHE for 30 min. The oxygen content was measured by nuclear microanalysis using the {sup 16}O(d,p) {sup 17}O* reaction. The oxygen content in the passive film is similar for the two alloys and equal to (12{plus minus}2) 10{sup 15} O/cm{sup 2}. The cationic compositions of the passive films have been determined by {sup 4}He channeling at two incident beam energies: 0.8 and 2.0 MeV. For the two alloys studied, a total cation content of (5{plus minus}2)10{sup 15} at/cm{sup 2} is found in the passive films. The corresponding thickness is about 12 A. There is an excess of oxygen, which can be attributed to the presence of hydroxyls and sulfate. A strong chromium enrichment is found in the passive film formed on both alloys: chromium represents about 50% of the cations. There is no evidence of molybdenum enrichment in the passive film formed on the Mo-alloyed stainless steel. The comparison of the results obtained at the two different incident beam energies (0.8MeV and 2MeV) reveals the existence of defects at the alloy/passive film interface. (author).

  11. Epitaxial growth of bcc-Fe{sub x}Co{sub 100-x} thin films on MgO(1 1 0) single-crystal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ohtake, Mitsuru, E-mail: ohtake@futamoto.elect.chuo-u.ac.j [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Nishiyama, Tsutomu; Shikada, Kouhei [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan); Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan)

    2010-07-15

    Fe{sub x}Co{sub 100-x} (x=100, 65, 50 at%) epitaxial thin films were prepared on MgO(1 1 0) single-crystal substrates heated at 300 deg. C by ultra-high vacuum molecular beam epitaxy. The film structure and the growth mechanism are discussed. FeCo(2 1 1) films with bcc structure grow epitaxially on MgO(1 1 0) substrates with two types of variants whose orientations are rotated around the film normal by 180 deg. each other for all compositions. Fe{sub x}Co{sub 100-x} film growth follows the Volmer Weber mode. X-ray diffraction analysis indicates the out-of-plane and the in-plane lattice spacings are in agreement with the values of respective bulk Fe{sub x}Co{sub 100-x} crystals with very small errors less than +-0.4%, suggesting the strains in the films are very small. High-resolution cross-sectional transmission electron microscopy shows that periodical misfit dislocations are preferentially introduced in the film at the Fe{sub 50}Co{sub 50}/MgO interface along the MgO[1 1-bar 0] direction. The presence of such periodical dislocations decreases the large lattice mismatch of about -17% existing at the FeCo/MgO interface along the MgO[1 1-bar 0] direction.

  12. A study on the electrodeposition of NiFe alloy thin films using chronocoulometry and electrochemical quartz crystal microgravimetry

    CERN Document Server

    Myung, N S

    2001-01-01

    Ni, Fe and NiFe alloy thin films were electrodeposited at a polycrystalline Au surface using a range of electrolytes and potentials. Coulometry and EQCM were used for real-time monitoring of electroplating efficiency of the Ni and Fe. The plating efficiency of NiFe alloy thin films was computed with the aid of ICP spectrometry. In general, plating efficiency increased to a steady value with deposition time. Plating efficiency of Fe was lower than that of Ni at -0.85 and -1.0 V but the efficiency approached to the similar plateau value to that of Ni at more negative potentials. The films with higher content of Fe showed different stripping behavior from the ones with higher content of Ni. Finally, compositional data and real-time plating efficiency are presented for films electrodeposited using a range of electrolytes and potentials.

  13. Electronic structure of Fe1.08Te bulk crystals and epitaxial FeTe thin films on Bi2Te3

    Science.gov (United States)

    Arnold, Fabian; Warmuth, Jonas; Michiardi, Matteo; Fikáček, Jan; Bianchi, Marco; Hu, Jin; Mao, Zhiqiang; Miwa, Jill; Singh, Udai Raj; Bremholm, Martin; Wiesendanger, Roland; Honolka, Jan; Wehling, Tim; Wiebe, Jens; Hofmann, Philip

    2018-02-01

    The electronic structure of thin films of FeTe grown on Bi2Te3 is investigated using angle-resolved photoemission spectroscopy, scanning tunneling microscopy and first principles calculations. As a comparison, data from cleaved bulk Fe1.08Te taken under the same experimental conditions is also presented. Due to the substrate and thin film symmetry, FeTe thin films grow on Bi2Te3 in three domains, rotated by 0°, 120°, and 240°. This results in a superposition of photoemission intensity from the domains, complicating the analysis. However, by combining bulk and thin film data, it is possible to partly disentangle the contributions from three domains. We find a close similarity between thin film and bulk electronic structure and an overall good agreement with first principles calculations, assuming a p-doping shift of 65 meV for the bulk and a renormalization factor of around two. By tracking the change of substrate electronic structure upon film growth, we find indications of an electron transfer from the FeTe film to the substrate. No significant change of the film’s electronic structure or doping is observed when alkali atoms are dosed onto the surface. This is ascribed to the film’s high density of states at the Fermi energy. This behavior is also supported by the ab initio calculations.

  14. Ordering phenomena in FeCo-films and Fe/Cr-multilayers: an X-ray and neutron scattering study

    Energy Technology Data Exchange (ETDEWEB)

    Nickel, B.

    2001-07-01

    The following topics are covered: critical phenomena in thin films, critical adsorption, finite size scaling, FeCo Ising model, kinematical scattering theory for thin films, FeCo thin films, growth and characterisation of single crystal FeCo thin films, X-ray study of ordering in FeCo films, antiferromagnetic coupling in Fe/Cr multilayers, neutron scattering on Fe/Cr multilayers (WL)

  15. Analysis of Crystal Structure of Fe3O4 Thin Films Based on Iron Sand Growth by Spin Coating Method

    Science.gov (United States)

    Rianto, D.; Yulfriska, N.; Murti, F.; Hidayati, H.; Ramli, R.

    2018-04-01

    Recently, iron sand used as one of base materials in the steel industry. However, the content of iron sand can be used as starting materials in sensor technology in the form of thin films. In this paper, we report the analysis of crystal structure of magnetite thin film based on iron sand from Tiram’s Beach. The magnetic content of sand separated by a permanent magnet, then it was milled at 30 hours milling time. In order to increase the purity of magnetite, it washed after milling using aquades under magnetic separation by a magnet permanent. The thin film has been prepared using iron (III) nitrate by sol–gel technique. The precursor is resulted by dissolving magnetite in oxalic acid and nitric acid. Then, solution of iron (III) nitrate dissolved in ethylene glycol was applied on glass substrates by spin coating. The X-Ray Diffraction is operated thin film characterization. The structure of magnetite has been studied based on X-Ray Peaks that correspond to magnetite content of thin films.

  16. Thermal analysis of compositionally modulated Fe/Y films

    International Nuclear Information System (INIS)

    Kajiura, M.; Morishita, T.; Togami, Y.; Tsushima, K.

    1987-01-01

    Structures of compositionally modulated Fe/Y films were studied by thermal analysis. The exothermic peak found in the DSC curve of (Fe 12 A/Y 12 A) most probably corresponds to crystallization of an amorphous material. SEM analysis suggested that the composition of crystallized (Fe 12 A/Y 12 A) was YFe2. It is concluded that a compositionally modulated (Fe 12 A/Y 12 A) is amorphous in structure as well as in magnetic properties

  17. Nonstoichiometry of Epitaxial FeTiO(3+delta) Films

    Science.gov (United States)

    2003-01-01

    nonstoichiometry of the FeTiO3 +8 films was probably produced by cation vacancies and disarrangement of Fe3+ and Ti4 ions, which randomly occupied both interstitial...and substitutional sites of the FeTiO 3 related structure. INTRODUCTION Solid solutions of ot-Fe20 3- FeTiO3 (hematite-ilmenite) series are known to...tried to confirm preparation conditions of stoichiometric FeTiO 3 films. According to a literature on bulk crystal growth of FeTiO3 [5], very low oxygen

  18. Orientation and magnetic properties of FePt and CoPt films grown on MgO(1 1 0) single-crystal substrate by electron-beam coevaporation

    Energy Technology Data Exchange (ETDEWEB)

    Yu Minghui [Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742 (United States); Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States)], E-mail: myu1@uno.edu; Ohguchi, H.; Zambano, A.; Takeuchi, I. [Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742 (United States); Liu, J.P. [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Josell, D.; Bendersky, L.A. [Metallurgy Division, Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States)

    2007-09-25

    We have studied the orientation and magnetic properties of FePt and CoPt films deposited by electron-beam co-evaporation on MgO(1 1 0) single-crystal substrates at substrate temperatures from 500 to 700 deg. C. We observed that long-range chemical ordering of the L1{sub 0} structure occurred over the entire range of substrate temperatures in FePt films and at 600 deg. C and up in CoPt films. Growth of FePt and CoPt yielded epitaxial films with cube-on-cube orientation of the pseudo-cubic L1{sub 0} lattice with respect to the cubic MgO. X-ray diffraction patterns and magnetization loops of the FePt and CoPt films revealed the existence of L1{sub 0} domains with the tetragonal c axis inclined at 45 deg. to the film plane, orientations (0 h h) and (h 0 h), as well as L1{sub 0} domains with the tetragonal c axis in the plane of the film, orientation (h h 0). The FePt and CoPt films for which X-ray diffraction indicated tetragonal phase was present all exhibited hard magnetic properties with easy axis along the [0 0 1] substrate direction as well as large in-plane magnetocrystalline anisotropy.

  19. Structural and magnetic properties of NdFeB and NdFeB/Fe films with Mo addition

    Energy Technology Data Exchange (ETDEWEB)

    Urse, M; Grigoras, M; Lupu, N; Chiriac, H, E-mail: urse@phys-iasi.ro [National Institute of R and D for Technical Physics, 47 Mangeron Blvd., 700050 Iasi (Romania)

    2011-07-06

    The influence of the Mo addition on the microstructure and magnetic properties of Nd-Fe-B and Nd-Fe-B/Fe films was studied. The coercivity is a key parameter in the control of technical performances of Nd-Fe-B films. A small amount of about 1 at.% Mo can enhance the coercivity of Nd-Fe-B film by controlling the growth of soft and hard magnetic grains. A coercivity of 22.1 kOe, a remanence ratio, M{sub r}/M{sub s}, of 0.83 and a maximum energy product of 8 MGOe were obtained for Ta/[NdFeBMo(1at.%)(540nm)/Ta films annealed at 650{sup 0}C for 20 minutes due to Mo precipitates formed at the Nd{sub 2}Fe{sub 14}B phase boundaries which prevent the nucleation and expansion of the magnetic domains. Simultaneous use of Mo as addition and the stratification of Nd-Fe-B-Mo films using Fe as spacer layer are important tools for the improvement of the hard magnetic properties of Nd-Fe-B films. The Ta/[NdFeBMo(1at.%)(180nm)/Fe(1nm)]x3/Ta multilayer film annealed at 620{sup 0}C exhibits an increase in the coercivity from 12.1 kOe to 22.8 kOe, in the remanence ratio from 0.77 to 0.80, and in the maximum energy product from 4.5 to 7.1 MGOe in comparison with Ta/Nd-Fe-B/Ta film. As compared to Ta/Nd-Fe-B/Ta film, the Ta/[NdFeBMo(1at.%)(180nm)/Fe(1nm)]x3/Ta film presents a decrease in the crystallization temperature of about 30{sup 0}C.

  20. Preparation of high magneto-optical performance and crystalline quality Ce{sub 1}Gd{sub 2}Fe{sub 5−x}Ga{sub x}O{sub 12} films on CLNGG substrate crystal

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Qiu-ping; Zheng, Ze-yuan; Lin, Nan-xi; Liu, Xiao-feng; Hong, Can-huang; Hu, Xiao-lin, E-mail: linamethyst@fzu.edu.cn; Zhuang, Nai-feng; Chen, Jian-zhong, E-mail: j.z.chen@fzu.edu.cn

    2016-11-01

    Thin films of Ce{sub 1}Gd{sub 2}Fe{sub 5−x}Ga{sub x}O{sub 12} (Ce,Ga:GIG) were prepared on Gd{sub 3}Ga{sub 5}O{sub 12} (GGG) and Ca{sub 2.90}Li{sub 0.30}Nb{sub 1.93}Ga{sub 2.76}O{sub 12} (CLNGG) substrates by using radio frequency magnetron sputtering technique. The phase, grain orientation, surface morphology, transmittance, magnetism and magnetic circular dichroism (MCD) properties of films were analyzed. And the effects of lattice mismatch and non-magnetic Ga{sup 3+}-doping were discussed. The results show that the films with higher crystallized quality and lower stress can be obtained by growing on CLNGG than on GGG. Moreover, the coercive force, magnetization, magneto-optical effect intensity and orientation of film can be effectively regulated by adjusting Ga{sup 3+}-doped concentration. - Highlights: • With excellent magneto-optical performance, Ce,Ga:GIG film has a good application prospect. • Ce,Ga:GIG film with high quality were prepared on CLNGG by RF magnetron sputtering. • Crystalline quality and morphology of films are intently related to the substrate. • Ga{sup 3+} doping obviously affect on magnetism and magneto-optical property of Ce:GIG film.

  1. Magnetostriction of Tb-Dy-Fe crystals

    International Nuclear Information System (INIS)

    Mei Wu; Okane, T.; Umeda, T.

    1998-01-01

    left angle 111 right angle -oriented twin free Tb-Dy-Fe single crystals, left angle 112 right angle - and left angle 110 right angle -oriented twinned ''single'' Tb-Dy-Fe crystals were prepared using floating zone melting crystal growth methods. Magnetostrictive performances of the crystals were investigated. Better low-field properties were observed in the left angle 110 right angle twinned crystals than in the left angle 112 right angle crystals. The highest properties were achieved in the left angle 111 right angle twin free single crystals. Even though there were still oxidized particles in the present left angle 111 right angle single crystals, a large magnetostrictive jump of 1700 ppm and a very low saturation magnetic field of 500 Oe were obtained. To understand magnetization and magnetostriction of different Tb-Dy-Fe crystals, theoretical modeling was carried out based on a simplified domain rotation model. Magnetization moment rotation paths of different domains were simulated and hence the resultant magnetostriction was obtained, which could adequately account for the experimental results of different crystals. The limitation of the domain rotation model was also discussed. (orig.)

  2. Magnetic Properties and Microstructure of FeOx/Fe/FePt and FeOx/FePt Films

    Directory of Open Access Journals (Sweden)

    Jai-Lin Tsai

    2013-01-01

    Full Text Available The Fe(6 nm/FePt film with perpendicular magnetization was deposited on the glass substrate. To study the oxygen diffusion effect on the coupling of Fe/FePt bilayer, the plasma oxidation with 0.5~7% oxygen flow ratio was performed during sputtered part of Fe layer and formed the FeOx(3 nm/Fe(3 nm/FePt trilayer. Two-step magnetic hysteresis loops were found in trilayer with oxygen flow ratio above 1%. The magnetization in FeOx and Fe/FePt layers was decoupled. The moments in FeOx layer were first reversed and followed by coupled Fe/FePt bilayer. The trilayer was annealed again at 500°C and 800°C for 3 minutes. When the FeOx(3 nm/Fe(3 nm/FePt trilayer was annealed at 500°C, the layers structure was changed to FeOx(6 nm/FePt bilayer due to oxygen diffusion. The hard-magnetic FeOx(6 nm/FePt film was coupled with single switching field. The FeOx/(disordered FePt layer structure was observed with further annealing at 800°C and presented soft-magnetic loop. In summary, the coupling between soft-magnetic Fe, FeOx layer, and hard-magnetic L10 FePt layer can be controlled by the oxygen diffusion behavior, and the oxidation of Fe layer was tuned by the annealing temperature. The ordered L10 FePt layer was deteriorated by oxygen and became disordered FePt when the annealed temperature was up to 800°C.

  3. Giant magnetoimpedance effect in sputtered single layered NiFe film and meander NiFe/Cu/NiFe film

    International Nuclear Information System (INIS)

    Chen, L.; Zhou, Y.; Lei, C.; Zhou, Z.M.; Ding, W.

    2010-01-01

    Giant magnetoimpedance (GMI) effect on NiFe thin film is very promising due to its application in developing the magnetic field sensors with highly sensitivity and low cost. In this paper, the single layered NiFe thin film and NiFe/Cu/NiFe thin film with a meander structure are prepared by the MEMS technology. The influences of sputtering parameters, film structure and conductor layer width on GMI effect in NiFe single layer and meander NiFe/Cu/NiFe film are investigated. Maximum of the GMI ratio in single layer and sandwich film is 5% and 64%, respectively. The results obtained are useful for developing the high-performance magnetic sensors based on NiFe thin film.

  4. NiFe epitaxial films with hcp and fcc structures prepared on bcc-Cr underlayers

    Energy Technology Data Exchange (ETDEWEB)

    Higuchi, Jumpei, E-mail: higuchi@futamoto.elect.chuo-u.ac.jp [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Ohtake, Mitsuru; Sato, Yoichi [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan); Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan)

    2011-09-30

    NiFe epitaxial films are prepared on Cr(211){sub bcc} and Cr(100){sub bcc} underlayers grown hetero-epitaxially on MgO single-crystal substrates by ultra-high vacuum rf magnetron sputtering. The film growth behavior and the crystallographic properties are studied by reflection high energy electron diffraction and pole figure X-ray diffraction. Metastable hcp-NiFe(11-bar 00) and hcp-NiFe(112-bar 0) crystals respectively nucleate on Cr(211){sub bcc} and Cr(100){sub bcc} underlayers, where the hcp-NiFe crystals are stabilized through hetero-epitaxial growth. The hcp-NiFe(11-bar 00) crystal is a single-crystal with the c-axis parallel to the substrate surface, whereas the hcp-NiFe(112-bar 0) crystal is a bi-crystal with the respective c-axes lying in plane and perpendicular each other. With increasing the film thickness, the hcp structure in the NiFe films starts to transform into more stable fcc structure by atomic displacement parallel to the hcp(0001) close packed plane. The resulting films consist of hcp and fcc crystals.

  5. NiFe epitaxial films with hcp and fcc structures prepared on bcc-Cr underlayers

    International Nuclear Information System (INIS)

    Higuchi, Jumpei; Ohtake, Mitsuru; Sato, Yoichi; Kirino, Fumiyoshi; Futamoto, Masaaki

    2011-01-01

    NiFe epitaxial films are prepared on Cr(211) bcc and Cr(100) bcc underlayers grown hetero-epitaxially on MgO single-crystal substrates by ultra-high vacuum rf magnetron sputtering. The film growth behavior and the crystallographic properties are studied by reflection high energy electron diffraction and pole figure X-ray diffraction. Metastable hcp-NiFe(11-bar 00) and hcp-NiFe(112-bar 0) crystals respectively nucleate on Cr(211) bcc and Cr(100) bcc underlayers, where the hcp-NiFe crystals are stabilized through hetero-epitaxial growth. The hcp-NiFe(11-bar 00) crystal is a single-crystal with the c-axis parallel to the substrate surface, whereas the hcp-NiFe(112-bar 0) crystal is a bi-crystal with the respective c-axes lying in plane and perpendicular each other. With increasing the film thickness, the hcp structure in the NiFe films starts to transform into more stable fcc structure by atomic displacement parallel to the hcp(0001) close packed plane. The resulting films consist of hcp and fcc crystals.

  6. Epitaxial Fe3Si/Ge/Fe3Si thin film multilayers grown on GaAs(001)

    International Nuclear Information System (INIS)

    Jenichen, B.; Herfort, J.; Jahn, U.; Trampert, A.; Riechert, H.

    2014-01-01

    We demonstrate Fe 3 Si/Ge/Fe 3 Si/GaAs(001) structures grown by molecular-beam epitaxy and characterized by transmission electron microscopy, electron backscattered diffraction, and X-ray diffraction. The bottom Fe 3 Si epitaxial film on GaAs is always single crystalline. The structural properties of the Ge film and the top Fe 3 Si layer depend on the substrate temperature during Ge deposition. Different orientation distributions of the grains in the Ge and the upper Fe 3 Si film were found. The low substrate temperature T s of 150 °C during Ge deposition ensures sharp interfaces, however, results in predominantly amorphous films. We find that the intermediate T s (225 °C) leads to a largely [111] oriented upper Fe 3 Si layer and polycrystal films. The high T s of 325 °C stabilizes the [001] oriented epitaxial layer structure, i.e., delivers smooth interfaces and single crystal films over as much as 80% of the surface area. - Highlights: • Fe 3 Si/Ge/Fe 3 Si/GaAs(001) structures are grown by MBE. • The bottom Fe 3 Si film is always single crystalline. • The properties of the Ge film depend on the substrate temperature during deposition. • Optimum growth conditions lead to almost perfect epitaxy of Ge on Fe 3 Si

  7. Microstructure and Magnetic Properties of Fe and Fe-alloy Thin Films Epitaxially Grown on MgO(100) Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Matsubara, Katsuki; Ohtake, Mitsuru; Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi, E-mail: matsubara@futamoto.elect.chuo-u.ac.jp [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan)

    2011-07-06

    Fe, Fe{sub 50}Co{sub 50}, and Fe{sub 80}Ni{sub 20} (at. %) single-crystal films with the (100){sub bcc} plane parallel to the substrate surface were prepared on MgO(100) single-crystals heated at 300 {sup 0}C by ultra high vacuum molecular beam epitaxy. The film growth mechanism, the film structure, and the magnetic properties were investigated. In-situ reflection high energy electron diffraction and X-ray diffraction analyses indicate that the strains in the films are very small though there are fairly large mismatches of -3.7{approx}-4.3% at the film/substrate interface. Cross-sectional high-resolution transmission electron microscopy shows that misfit dislocations are introduced in the film at the interface. Dislocations are also observed in the film up to around 10{approx}20 nm distance from the interface. The presence of such dislocation relieves the strain caused by the lattice mismatch. The in-plane magnetization properties of these films reflect the magnetocrystalline anisotropies of respective bulk Fe, Fe{sub 50}Co{sub 50}, and Fe{sub 80}Ni{sub 20} crystals.

  8. Microstructure and Magnetic Properties of Fe and Fe-alloy Thin Films Epitaxially Grown on MgO(100) Substrates

    International Nuclear Information System (INIS)

    Matsubara, Katsuki; Ohtake, Mitsuru; Futamoto, Masaaki; Kirino, Fumiyoshi

    2011-01-01

    Fe, Fe 50 Co 50 , and Fe 80 Ni 20 (at. %) single-crystal films with the (100) bcc plane parallel to the substrate surface were prepared on MgO(100) single-crystals heated at 300 0 C by ultra high vacuum molecular beam epitaxy. The film growth mechanism, the film structure, and the magnetic properties were investigated. In-situ reflection high energy electron diffraction and X-ray diffraction analyses indicate that the strains in the films are very small though there are fairly large mismatches of -3.7∼-4.3% at the film/substrate interface. Cross-sectional high-resolution transmission electron microscopy shows that misfit dislocations are introduced in the film at the interface. Dislocations are also observed in the film up to around 10∼20 nm distance from the interface. The presence of such dislocation relieves the strain caused by the lattice mismatch. The in-plane magnetization properties of these films reflect the magnetocrystalline anisotropies of respective bulk Fe, Fe 50 Co 50 , and Fe 80 Ni 20 crystals.

  9. Fe3O4 thin films sputter deposited from iron oxide targets

    International Nuclear Information System (INIS)

    Peng, Yingguo; Park, Chandro; Laughlin, David E.

    2003-01-01

    Fe 3 O 4 thin films have been directly sputter deposited from a target consisting of a mixture of Fe 3 O 4 and Fe 2 O 3 onto Si and glass substrates. The magnetic properties and microstructures of the films have been characterized and correlated. The columnar growth of the Fe 3 O 4 grains was found to be initialized from the substrate surface without any critical thickness. Substrate bias was found to be a very effective means of improving the crystal quality and magnetic properties of the thin films. The crystallographic defects revealed by high resolution transmission electron microscopy seem to be a characteristic of the films prepared by this method

  10. On dewetting of thin films due to crystallization (crystallization dewetting).

    Science.gov (United States)

    Habibi, Mehran; Rahimzadeh, Amin; Eslamian, Morteza

    2016-03-01

    Drying and crystallization of a thin liquid film of an ionic or a similar solution can cause dewetting in the resulting thin solid film. This paper aims at investigating this type of dewetting, herein termed "crystallization dewetting", using PbI2 dissolved in organic solvents as the model solution. PbI2 solid films are usually used in X-ray detection and lead halide perovskite solar cells. In this work, PbI2 films are fabricated using spin coating and the effect of major parameters influencing the crystallization dewetting, including the type of the solvent, solution concentration, drying temperature, spin speed, as well as imposed vibration on the substrate are studied on dewetting, surface profile and coverage, using confocal scanning laser microscopy. Simplified hydrodynamic governing equations of crystallization in thin films are presented and using a mathematical representation of the process, it is phenomenologically demonstrated that crystallization dewetting occurs due to the absorption and consumption of the solution surrounding a growing crystal. Among the results, it is found that a low spin speed (high thickness), a high solution concentration and a low drying temperature promote crystal growth, and therefore crystallization dewetting. It is also shown that imposed vibration on the substrate can affect the crystal size and crystallization dewetting.

  11. Magnetoelastic coupling in TbFe2 (110) thin films

    International Nuclear Information System (INIS)

    Ciria, M.; Arnaudas, J.I.; Dufour, C.; Oderno, V.; Dumesnil, K.; del Moral, A.

    1997-01-01

    We have determined the rhombohedral magnetoelastic stress of a Laves phase TbFe 2 (110) single-crystal film, grown by molecular-beam epitaxy. The film thickness was 1300 Angstrom. The magnetoelastic stress was directly measured by using a low-temperature cantilever capacitive method, between 300 and 10 K. The isotherms clearly display the coercive field but, unlike bulk alloy behavior, do not saturate even at the maximum field of 12 T. The determined rhombohedral magnetoelastic parameter of the film is B ε,2 =-0.43 GPa, at 0 K and 12 T, which is 0.67 times the value for bulk TbFe 2 . B ε,2 follows a power m 3 of the reduced magnetization m, indicating a single-ion volume origin for the rhombohedral magnetoelastic stress of this film. Measurements performed in a 300 Angstrom TbFe 2 (110) film deposited onto a YFe 2 buffer show that the coercive field is drastically lowered and that the magnetoelastic distortion is negligible. copyright 1997 American Institute of Physics

  12. Fe3O4 epitaxial films

    KAUST Repository

    Liu, Xiang; Mi, Wenbo; Zhang, Qiang; Zhang, Xixiang

    2017-01-01

    fast charge ordering process and a continuous formation process of trimeron, which is comfirmed by the temperature-dependent Raman spectra. Just below T-V, the twofold AMR in Fe3O4(100) film originates from uniaxial magnetic anisotropy. The fourfold AMR

  13. EXAFS study of the stability of amorphous TbFe thin films

    International Nuclear Information System (INIS)

    Samant, M.G.; Marinero, E.E.; Robinson, C.; Cargill, G.S.

    1989-01-01

    This paper discusses the measurement of the local atomic structure of Fe in Au doped Tb-Fe thin film alloys by the use of EXAFS. The as deposited sample shows structural features which are essentially identical to those of the undoped films. Au additions stabilizes the amorphous structure against recrystallization, however, the loss of magnetic anisotropy under thermal annealing is not reduced. This demonstrates that magnetic relaxation in these alloys does not involve crystallization of the amorphous structure

  14. Magnetic properties of partially oxidized Fe films

    Science.gov (United States)

    Garcia, Miguel Angel; Lopez-Dominguez, Victor; Hernando, Antonio

    Hybrid magnetic nanostructures exhibit appealing properties due to interface and proximity effects. A simple and interesting system of hybrid magnetic nanomaterials are partially oxidized ferromagnetic films. We have fabricated Fe films by thermal evaporation and performed a partial oxidation to magnetite (Fe3O4) by annealing in air at different times and temperatures. The magnetic properties of the films evolve from those of pure metallic iron to pure magnetite, showing intermediate states where the proximity effects control the magnetic behavior. At some stages, the magnetization curves obtained by SQUID and MOKE magnetometry exhibit important differences due to the dissimilar contribution of both phases to the magneto-optical response of the system This work has been supported by the Ministerio Español de Economia y Competitividad (MINECO) MAT2013-48009-C4-1. V.L.D and M.A.G. acknowledges financial support from BBVA foundation.

  15. Magnetic Properties of FeNi-Based Thin Film Materials with Different Additives

    Directory of Open Access Journals (Sweden)

    Cai Liang

    2014-07-01

    Full Text Available This paper presents a study of FeNi-based thin film materials deposited with Mo, Al and B using a co-sputtering process. The existence of soft magnetic properties in combination with strong magneto-mechanical coupling makes these materials attractive for sensor applications. Our findings show that FeNi deposited with Mo or Al yields magnetically soft materials and that depositing with B further increases the softness. The out-of-plane magnetic anisotropy of FeNi thin films is reduced by depositing with Al and completely removed by depositing with B. The effect of depositing with Mo is dependent on the Mo concentration. The coercivity of FeNiMo and FeNiAl is reduced to less than a half of that of FeNi, and a value as low as 40 A/m is obtained for FeNiB. The surfaces of the obtained FeNiMo, FeNiAl and FeNiB thin films reveal very different morphologies. The surface of FeNiMo shows nano-cracks, while the FeNiAl films show large clusters and fewer nano-cracks. When FeNi is deposited with B, a very smooth morphology is obtained. The crystal structure of FeNiMo strongly depends on the depositant concentration and changes into an amorphous structure at a higher Mo level. FeNiAl thin films remain polycrystalline, even at a very high concentration of Al, and FeNiB films are amorphous, even at a very low concentration of B.

  16. Magnetic properties of FeNi-based thin film materials with different additives

    KAUST Repository

    Liang, C.

    2014-07-04

    This paper presents a study of FeNi-based thin film materials deposited with Mo, Al and B using a co-sputtering process. The existence of soft magnetic properties in combination with strong magneto-mechanical coupling makes these materials attractive for sensor applications. Our findings show that FeNi deposited with Mo or Al yields magnetically soft materials and that depositing with B further increases the softness. The out-of-plane magnetic anisotropy of FeNi thin films is reduced by depositing with Al and completely removed by depositing with B. The effect of depositing with Mo is dependent on the Mo concentration. The coercivity of FeNiMo and FeNiAl is reduced to less than a half of that of FeNi, and a value as low as 40 A/m is obtained for FeNiB. The surfaces of the obtained FeNiMo, FeNiAl and FeNiB thin films reveal very different morphologies. The surface of FeNiMo shows nano-cracks, while the FeNiAl films show large clusters and fewer nano-cracks. When FeNi is deposited with B, a very smooth morphology is obtained. The crystal structure of FeNiMo strongly depends on the depositant concentration and changes into an amorphous structure at a higher Mo level. FeNiAl thin films remain polycrystalline, even at a very high concentration of Al, and FeNiB films are amorphous, even at a very low concentration of B. 2014 by the authors.

  17. MFM study of NdFeB and NdFeB/Fe/NdFeB thin films

    International Nuclear Information System (INIS)

    Gouteff, P.C.; Folks, L.; Street, R.

    1998-01-01

    Domain structures of NdFeB thin films, ranging in thickness between 1500 and 29 nm, have been studied qualitatively by magnetic force microscopy (MFM). Samples were prepared using a range of sputtering conditions resulting in differences in properties such as texture, coercivity and magnetic saturation. MFM images of all the films showed extensive interaction domain structures, similar to those observed in nanocrystalline bulk NdFeB. An exchange-coupled NdFeB/Fe/NdFeB trilayer with layer thicknesses 18 nm/15 nm/18 nm, respectively, was also examined using MFM. (orig.)

  18. Growth of single crystals of BaFe12O19 by solid state crystal growth

    Science.gov (United States)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-10-01

    Single crystals of BaFe12O19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe12O19 are buried in BaFe12O19+1 wt% BaCO3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe12O19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe12O19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth.

  19. Growth of single crystals of BaFe12O19 by solid state crystal growth

    International Nuclear Information System (INIS)

    Fisher, John G.; Sun, Hengyang; Kook, Young-Geun; Kim, Joon-Seong; Le, Phan Gia

    2016-01-01

    Single crystals of BaFe 12 O 19 are grown for the first time by solid state crystal growth. Seed crystals of BaFe 12 O 19 are buried in BaFe 12 O 19 +1 wt% BaCO 3 powder, which are then pressed into pellets containing the seed crystals. During sintering, single crystals of BaFe 12 O 19 up to ∼130 μm thick in the c-axis direction grow on the seed crystals by consuming grains from the surrounding polycrystalline matrix. Scanning electron microscopy-energy dispersive spectroscopy analysis shows that the single crystal and the surrounding polycrystalline matrix have the same chemical composition. Micro-Raman scattering shows the single crystal to have the BaFe 12 O 19 structure. The optimum growth temperature is found to be 1200 °C. The single crystal growth behavior is explained using the mixed control theory of grain growth. - Highlights: • Single crystals of BaFe 12 O 19 are grown by solid state crystal growth. • A single crystal up to ∼130 μm thick (c-axis direction) grows on the seed crystal. • The single crystal and surrounding ceramic matrix have similar composition. • Micro-Raman scattering shows the single crystal has the BaFe 12 O 19 structure.

  20. Removal of FePO4 and Fe3(PO4)2 crystals on the surface of passive fillers in Fe0/GAC reactor using the acclimated bacteria

    International Nuclear Information System (INIS)

    Lai, Bo; Zhou, Yuexi; Yang, Ping; Wang, Juling; Yang, Jinghui; Li, Huiqiang

    2012-01-01

    Highlights: ► Fe 3 (PO 4 ) 2 and FePO 4 crystals would weaken treatment efficiency of Fe 0 /GAC reactor. ► Fe 3 (PO 4 ) 2 and FePO 4 crystals could be removed by the acclimated bacteria. ► FeS and sulfur in the passive film would be removed by the sulfur-oxidizing bacteria. ► Develop a cost-effective bio-regeneration technology for the passive fillers. - Abstract: As past studies presented, there is obvious defect that the fillers in the Fe 0 /GAC reactor begin to be passive after about 60 d continuous running, although the complicated, toxic and refractory ABS resin wastewater can be pretreated efficiently by the Fe 0 /GAC reactor. During the process, the Fe 3 (PO 4 ) 2 and FePO 4 crystals with high density in the passive film are formed by the reaction between PO 4 3− and Fe 2+ /Fe 3+ . Meanwhile, they obstruct the formation of macroscopic galvanic cells between Fe 0 and GAC, which will lower the wastewater treatment efficiency of Fe 0 /GAC reactor. In this study, in order to remove the Fe 3 (PO 4 ) 2 and FePO 4 crystals on the surface of the passive fillers, the bacteria were acclimated in the passive Fe 0 /GAC reactor. According to the results, it can be concluded that the Fe 3 (PO 4 ) 2 and FePO 4 crystals with high density in the passive film could be decomposed or removed by the joint action between the typical propionic acid type fermentation bacteria and sulfate reducing bacteria (SRB), whereas the PO 4 3− ions from the decomposition of the Fe 3 (PO 4 ) 2 and FePO 4 crystals were released into aqueous solution which would be discharged from the passive Fe 0 /GAC reactor. Furthermore, the remained FeS and sulfur (S) in the passive film also can be decomposed or removed easily by the oxidation of the sulfur-oxidizing bacteria. This study provides some theoretical references for the further study of a cost-effective bio-regeneration technology to solve the passive problems of the fillers in the zero-valent iron (ZVI) or Fe 0 /GAC reactor.

  1. Chemically abrupt interface between Ce oxide and Fe films

    International Nuclear Information System (INIS)

    Lee, H.G.; Lee, D.; Kim, S.; Kim, S.G.; Hwang, Chanyong

    2005-01-01

    A chemically abrupt Fe/Ce oxide interface can be formed by initial oxidation of an Fe film followed by deposition of Ce metal. Once a Ce oxide layer is formed on top of Fe, it acts a passivation barrier for oxygen diffusion. Further deposition of Ce metal followed by its oxidation preserve the abrupt interface between Ce oxide and Fe films. The Fe and Ce oxidation states have been monitored at each stage using X-ray photoelectron spectroscopy

  2. Magnetic and thermal properties of amorphous TbFeCo alloy films

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ke, E-mail: K.Wang@hqu.edu.cn; Dong, Shuo; Huang, Ya; Qiu, Yuzhen

    2017-07-15

    Highlights: • Significant increase in magnetization is observed in TbFeCo upon crystallization. • The crystallization temperature is determined in the range between 400 and 450 °C. • The activation barriers for structural changes are obtained successfully. • Better thermal stability against crystallization and oxidation is demonstrated in FeCo-rich sample than Tb-rich type. - Abstract: Amorphous TbFeCo material with perpendicular magnetic anisotropy is currently attracting more attention for potential applications in spintronic devices and logic memories. We systematically investigate magnetic, structural, thermal, optical and electrical properties of TbFeCo alloy films. It shows out-of-plane easy axis of the films turns into in-plane orientation after annealing. Significant increase in saturation magnetization in the temperature range between 400 and 450 °C is revealed by thermomagnetic measurements. The occurrence of crystallization and oxidation at high temperatures is confirmed by X-ray diffraction measurements. Pronounced changes in optical reflectance and sheet resistance are observed with temperature, in line with structural relaxation and change. The activation barriers for crystallization and oxidation are determined to be 1.01 eV and 0.83 eV, respectively, for FeCo-rich and Tb-rich samples. Better thermal stability against crystallization and oxidation is demonstrated in the FeCo-rich sample than the Tb-rich type. Our results provide some useful information for the alloy used in device fabrication.

  3. Synthesis and characterization of Fe doped cadmium selenide thin films by spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Abhijit A., E-mail: aay_physics@yahoo.co.in [Thin Film Physics Laboratory, Department of Physics, Electronics and Photonics, Rajarshi Shahu Mahavidyalaya, Latur 413 512, Maharashtra (India)

    2012-12-05

    Highlights: Black-Right-Pointing-Pointer Simple and inexpensive method to dope trivalent Fe in CdSe thin films. Black-Right-Pointing-Pointer Fe doped CdSe thin films are highly photosensitive. Black-Right-Pointing-Pointer AFM analysis shows uniform deposition of film over the entire substrate surface. Black-Right-Pointing-Pointer The band gap energy decreases from 1.74 to 1.65 eV with Fe doping. Black-Right-Pointing-Pointer Film resistivity decreases to 6.76 Multiplication-Sign 10{sup 4} {Omega}-cm with Fe doping in CdSe thin films. - Abstract: Undoped and Fe doped CdSe thin films have been deposited onto the amorphous and fluorine doped tin oxide coated glass substrates by spray pyrolysis. The Fe doping concentration has been optimized by photoelectrochemical (PEC) characterization technique. The structural, surface morphological, compositional, optical and electrical properties of undoped and Fe doped CdSe thin films have been studied. X-ray diffraction study reveals that the as deposited CdSe films possess hexagonal crystal structure with preferential orientation along (1 0 0) plane. AFM analysis shows uniform deposition of the film over the entire substrate surface with minimum surface roughness of 7.90 nm. Direct allowed type of transition with band gap decreasing from 1.74 to 1.65 eV with Fe doping has been observed. The activation energy of the films has been found to be in the range of 0.14-0.19 eV at low temperature and 0.27-0.44 eV at high temperature. Semi-conducting behavior has been observed from resistivity measurements. The thermoelectric power measurements reveal that the films are of n type.

  4. Thickness-modulated anisotropic ferromagnetism in Fe-doped epitaxial HfO2 thin films

    Science.gov (United States)

    Liu, Wenlong; Liu, Ming; Zhang, Ruyi; Ma, Rong; Wang, Hong

    2017-10-01

    Epitaxial tetragonal Fe-doped Hf0.95Fe0.05O2 (FHO) thin films with various thicknesses were deposited on (001)-oriented NdCaAlO4 (NCAO) substrates by using a pulsed laser deposition (PLD) system. The crystal structure and epitaxial nature of the FHO thin films were confirmed by typical x-ray diffraction (XRD) θ-2θ scan and reciprocal space mapping (RSM). The results indicate that two sets of lattice sites exist with two different crystal orientations [(001) and (100)] in the thicker FHO thin films. Further, the intensity of the (100) direction increases with the increase in thicknesses, which should have a significant effect on the anisotropic magnetization of the FHO thin films. Meanwhile, all the FHO thin films possess a tetragonal phase structure. An anisotropy behavior in magnetization has been observed in the FHO thin films. The anisotropic magnetization of the FHO thin films is slowly weakened as the thickness increases. Meanwhile, the saturation magnetization (Ms) of both in-plane and out-of-plane decreases with the increase in the thickness. The change in the anisotropic magnetization and Ms is attributed to the crystal lattice and the variation in the valence of Fe ions. These results indicate that the thickness-modulated anisotropic ferromagnetism of the tetragonal FHO epitaxial thin films is of potential use for the integration of metal-oxide semiconductors with spintronics.

  5. Domains in Ferroic Crystals and Thin Films

    CERN Document Server

    Tagantsev, Alexander K; Fousek, Jan

    2010-01-01

    Domains in Ferroic Crystals and Thin Films presents experimental findings and theoretical understanding of ferroic (non-magnetic) domains developed during the past 60 years. It addresses the situation by looking specifically at bulk crystals and thin films, with a particular focus on recently-developed microelectronic applications and methods for observation of domains with techniques such as scanning force microscopy, polarized light microscopy, scanning optical microscopy, electron microscopy, and surface decorating techniques. Domains in Ferroic Crystals and Thin Films covers a large area of material properties and effects connected with static and dynamic properties of domains, which are extremely relevant to materials referred to as ferroics. In most solid state physics books, one large group of ferroics is customarily covered: those in which magnetic properties play a dominant role. Numerous books are specifically devoted to magnetic ferroics and cover a wide spectrum of magnetic domain phenomena. In co...

  6. Growth of Fe2O3 thin films by atomic layer deposition

    International Nuclear Information System (INIS)

    Lie, M.; Fjellvag, H.; Kjekshus, A.

    2005-01-01

    Thin films of α-Fe 2 O 3 (α-Al 2 O 3 -type crystal structure) and γ-Fe 2 O 3 (defect-spinel-type crystal structure) have been grown by the atomic layer deposition (ALD) technique with Fe(thd) 3 (iron derivative of Hthd = 2,2,6,6-tetramethylheptane-3,5-dione) and ozone as precursors. It has been shown that an ALD window exists between 160 and 210 deg. C. The films have been characterized by various techniques and are shown to comprise (001)-oriented columns of α-Fe 2 O 3 with no in-plane orientation when grown on soda-lime-glass and Si(100) substrates. Good quality films have been made with thicknesses ranging from 10 to 130 nm. Films grown on α-Al 2 O 3 (001) and MgO(100) substrates have the α-Fe 2 O 3 and γ-Fe 2 O 3 crystal structure, respectively, and consist of highly oriented columns with in-plane orientations matching those of the substrates

  7. Electrosynthesis and characterization of Fe doped CdSe thin films from ethylene glycol bath

    International Nuclear Information System (INIS)

    Pawar, S.M.; Moholkar, A.V.; Rajpure, K.Y.; Bhosale, C.H.

    2007-01-01

    The CdSe and Fe doped CdSe (Fe:CdSe) thin films have been electrodeposited potentiostatically onto the stainless steel and fluorine doped tin oxide (FTO) glass substrates, from ethylene glycol bath containing (CH 3 COO) 2 .Cd.2H 2 O, SeO 2 , and FeCl 3 at room temperature. The doping concentration of Fe is optimized by using (photo) electrochemical (PEC) characterization technique. The deposition mechanism and Fe incorporation are studied by cyclic voltammetry. The structural, surface morphological and optical properties of the deposited CdSe and Fe:CdSe thin films have been studied by X-ray diffraction, scanning electron microscopy (SEM) and optical absorption techniques respectively. The PEC study shows that Fe:CdSe thin films are more photosensitive than that of undoped CdSe thin films. The X-ray diffraction analysis shows that the films are polycrystalline with hexagonal crystal structure. SEM studies reveal that the films with uniformly distributed grains over the entire surface of the substrate. The complete surface morphology has been changed after doping. Optical absorption study shows the presence of direct transition and a considerable decrease in bandgap, E g from 1.95 to 1.65 eV

  8. Spectroscopic ellipsometry study of FePt nanoparticle films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.J.; Lo, C.C.H. [Ames Laboratory, Iowa State University, Ames, IA 50011 (United States); Yu, A.C.C. [Sony Corporation, Sendai Technology Center, 3-4-1 Sakuragi, Miyagi 985-0842 (Japan); Fan, M. [School of Materials Science and Technology, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2006-12-15

    The optical properties of a FePt nanoparticle film were investigated using spectroscopic ellipsometry. The FePt nanoparticle film of thickness about 15 nm was prepared by deposition of FePt nanoparticles directly on a Si substrate. The nanoparticle film was annealed at 600 C in vacuum for two hours before the measurements. The optical properties of the FePt nanoparticle film showed distinctively different spectra from those obtained from the bulk and thin film FePt samples, in particular in the low photon energy range (below 3.5 eV) where the nanoparticle film exhibited a relatively flat refractive index and a substantially lower extinction coefficient than the bulk and epitaxial thin film samples. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. On the crystallization of amorphous germanium films

    Science.gov (United States)

    Edelman, F.; Komem, Y.; Bendayan, M.; Beserman, R.

    1993-06-01

    The incubation time for crystallization of amorphous Ge (a-Ge) films, deposited by e-gun, was studied as a function of temperature between 150 and 500°C by means of both in situ transmission electron microscopy and Raman scattering spectroscopy. The temperature dependence of t0 follows an Arrhenius curve with an activation energy of 2.0 eV for free-sustained a-Ge films. In the case where the a-Ge films were on Si 3N 4 substrate, the activation energy of the incubation process was 1.3 eV.

  10. Inkjet printing of single-crystal films.

    Science.gov (United States)

    Minemawari, Hiromi; Yamada, Toshikazu; Matsui, Hiroyuki; Tsutsumi, Jun'ya; Haas, Simon; Chiba, Ryosuke; Kumai, Reiji; Hasegawa, Tatsuo

    2011-07-13

    The use of single crystals has been fundamental to the development of semiconductor microelectronics and solid-state science. Whether based on inorganic or organic materials, the devices that show the highest performance rely on single-crystal interfaces, with their nearly perfect translational symmetry and exceptionally high chemical purity. Attention has recently been focused on developing simple ways of producing electronic devices by means of printing technologies. 'Printed electronics' is being explored for the manufacture of large-area and flexible electronic devices by the patterned application of functional inks containing soluble or dispersed semiconducting materials. However, because of the strong self-organizing tendency of the deposited materials, the production of semiconducting thin films of high crystallinity (indispensable for realizing high carrier mobility) may be incompatible with conventional printing processes. Here we develop a method that combines the technique of antisolvent crystallization with inkjet printing to produce organic semiconducting thin films of high crystallinity. Specifically, we show that mixing fine droplets of an antisolvent and a solution of an active semiconducting component within a confined area on an amorphous substrate can trigger the controlled formation of exceptionally uniform single-crystal or polycrystalline thin films that grow at the liquid-air interfaces. Using this approach, we have printed single crystals of the organic semiconductor 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C(8)-BTBT) (ref. 15), yielding thin-film transistors with average carrier mobilities as high as 16.4 cm(2) V(-1) s(-1). This printing technique constitutes a major step towards the use of high-performance single-crystal semiconductor devices for large-area and flexible electronics applications.

  11. Preparation of Nd-doped BiFeO{sub 3} films and their electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Meng [Key Laboratory of Auxiliary Chemistry and Technology for Chemical Industry, Ministry of Education of China, Shaanxi University of Science and Technology, Weiyang District, Xi' an 710021 (China); Tan Guoqiang, E-mail: tan3114@163.com [Key Laboratory of Auxiliary Chemistry and Technology for Chemical Industry, Ministry of Education of China, Shaanxi University of Science and Technology, Weiyang District, Xi' an 710021 (China); Xue Xu; Xia Ao; Ren Huijun [Key Laboratory of Auxiliary Chemistry and Technology for Chemical Industry, Ministry of Education of China, Shaanxi University of Science and Technology, Weiyang District, Xi' an 710021 (China)

    2012-09-01

    The Nd-doped BiFeO{sub 3} thin films were prepared on SnO{sub 2}(FTO) substrates spin-coated by the sol-gel method using Nd(NO{sub 3}){sub 3}{center_dot}6H{sub 2}O, Fe(NO{sub 3}){sub 3}{center_dot}9H{sub 2}O and Bi(NO{sub 3}){sub 3}{center_dot}5H{sub 2}O as raw materials. The microstructure and electric properties of the BiFeO{sub 3} thin films were characterized and tested. The results indicate that the diffraction peak of the Nd-doped BiFeO{sub 3} films is shifted towards right as the doping amounts are increased. The structure is transformed from the rhombohedral to pseudotetragonal phase. The crystal grain is changed from an elliptical to irregular polyhedron. Structure transition occurring in the Bi{sub 0.85}Nd{sub 0.15}FeO{sub 3} films gives rise to the largest Pr of 64 {mu}C/cm{sup 2}. The leakage conductance of the Nd doped thin films is reduced. The dielectric constant and dielectric loss of Bi{sub 0.85}Nd{sub 0.15}FeO{sub 3} thin film at 10 kHz are 190 and 0.017 respectively.

  12. Influences of annealing temperature on sprayed CuFeO2 thin films

    Science.gov (United States)

    Abdelwahab, H. M.; Ratep, A.; Abo Elsoud, A. M.; Boshta, M.; Osman, M. B. S.

    2018-06-01

    Delafossite CuFeO2 thin films were successfully prepared onto quartz substrates using simple spray pyrolysis technique. Post annealing under nitrogen atmosphere for 2 h was necessary to form delafossite CuFeO2 phase. The effect of alteration in annealing temperature (TA) 800, 850 and 900 °C was study on structural, morphology and optical properties. The XRD results for thin film annealed at TA = 850 °C show single phase CuFeO2 with rhombohedral crystal system and R 3 bar m space group with preferred orientation along (0 1 2). The prepared copper iron oxide thin films have an optical transmission ranged ∼40% in the visible region. The optical direct optical band gap of the prepared thin films was ranged ∼2.9 eV.

  13. Nanocrystalline Pd:NiFe2O4 thin films: A selective ethanol gas sensor

    International Nuclear Information System (INIS)

    Rao, Pratibha; Godbole, R.V.; Bhagwat, Sunita

    2016-01-01

    In this work, Pd:NiFe 2 O 4 thin films were investigated for the detection of reducing gases. These films were fabricated using spray pyrolysis technique and characterized using X-ray diffraction (XRD) to confirm the crystal structure. The surface morphology was studied using scanning electron microscopy (SEM). Magnetization measurements were carried out using SQUID VSM, which shows ferrimagnetic behavior of the samples. These thin film sensors were tested against methanol, ethanol, hydrogen sulfide and liquid petroleum gas, where they were found to be more selective to ethanol. The fabricated thin film sensors exhibited linear response signal for all the gases with concentrations up to 5 w/o Pd. Reduction in optimum operating temperature and enhancement in response was also observed. Pd:NiFe 2 O 4 thin films exhibited faster response and recovery characteristic. These sensors have potential for industrial applications because of their long-term stability, low power requirement and low production cost. - Highlights: • Ethanol gas sensors based on Pd:NiFe 2 O 4 nanoparticle thin film were fabricated. • Pd incorporation in NiFe 2 O 4 matrix inhibits grain growth. • The sensors were more selective to ethanol gas. • Sensors exhibited fast response and recovery when doped with palladium. • Pd:NiFe 2 O 4 thin film sensor displays excellent long–term stability.

  14. Effect of epitaxial strain and lattice mismatch on magnetic and transport behaviors in metamagnetic FeRh thin films

    Science.gov (United States)

    Xie, Yali; Zhan, Qingfeng; Shang, Tian; Yang, Huali; Wang, Baomin; Tang, Jin; Li, Run-Wei

    2017-05-01

    We grew 80 nm FeRh films on different single crystals with various lattice constants. FeRh films on SrTiO3 (STO) and MgO substrates exhibit an epitaxial growth of 45° in-plane structure rotation. In contrast, FeRh on LaAlO3 (LAO) displays a mixed epitaxial growth of both 45° in-plane structure rotation and cube-on-cube relationships. Due to the different epitaxial growth strains and lattice mismatch values, the critical temperature for the magnetic phase transition of FeRh can be changed between 405 and 360 K. In addition, the external magnetic field can shift this critical temperature to low temperature in different rates for FeRh films grown on different substrates. The magnetoresistance appears a maximum value at different temperatures between 320 and 380 K for FeRh films grown on different substrates.

  15. Effect of epitaxial strain and lattice mismatch on magnetic and transport behaviors in metamagnetic FeRh thin films

    Directory of Open Access Journals (Sweden)

    Yali Xie

    2017-05-01

    Full Text Available We grew 80 nm FeRh films on different single crystals with various lattice constants. FeRh films on SrTiO3 (STO and MgO substrates exhibit an epitaxial growth of 45° in-plane structure rotation. In contrast, FeRh on LaAlO3 (LAO displays a mixed epitaxial growth of both 45° in-plane structure rotation and cube-on-cube relationships. Due to the different epitaxial growth strains and lattice mismatch values, the critical temperature for the magnetic phase transition of FeRh can be changed between 405 and 360 K. In addition, the external magnetic field can shift this critical temperature to low temperature in different rates for FeRh films grown on different substrates. The magnetoresistance appears a maximum value at different temperatures between 320 and 380 K for FeRh films grown on different substrates.

  16. BiFeO3 Crystal Structure at Low Temperatures

    International Nuclear Information System (INIS)

    Palewicz, A.; Sosnowska, I.; Przenioslo, R.; Hewat, A.W.

    2010-01-01

    The crystal and magnetic structure of BiFeO 3 have been studied with the use of high resolution neutron diffraction between 5 K and 300 K. The atomic coordinates in BiFeO 3 are almost unchanged between 5 K and 300 K. (authors)

  17. Strengthening mechanisms of Fe nanoparticles for single crystal Cu–Fe alloy

    International Nuclear Information System (INIS)

    Shi, Guodong; Chen, Xiaohua; Jiang, Han; Wang, Zidong; Tang, Hao; Fan, Yongquan

    2015-01-01

    A single crystal Cu–Fe alloy with finely dispersed precipitate Fe nanoparticles was fabricated in this study. The interface relationship of iron nanoparticle and copper matrix was analyzed with a high-resolution transmission electron microscope (HRTEM), and the effect of Fe nanoparticles on mechanical properties of single crystal Cu–Fe alloy was discussed. Results show that, the finely dispersed Fe nanoparticles can be obtained under the directional solidification condition, with the size of 5–50 nm and the coherent interface between the iron nanoparticle and the copper matrix. Single crystal Cu–Fe alloy possesses improved tensile strength of 194.64 MPa, and total elongation of 44.72%, respectively, at room temperature, in contrast to pure Cu sample. Nanoparticles which have coherent interface with matrix can improve the dislocation motion state. Some dislocations can slip through the nanoparticle along the coherent interface and some dislocations can enter into the nanoparticles. Thus to improve the tensile strength of single crystal Cu–Fe alloy without sacrificing the ductility simultaneously. Based on the above analyses, strengthening mechanisms of Fe nanoparticles for single crystal Cu–Fe alloy was described

  18. BiFeO3 thin films: Novel effects

    Indian Academy of Sciences (India)

    photolithography followed by etching of the silver film. Saturation ... Fe in +3 state. Films thus obtained are therefore highly resistive (ρ ∼ 108–109 cm) and hence exhibit saturated ferroelectric hysteresis loop (figure 3). Anomaly in ... BiFeO3 bulk sample by Rogniskaya et al [4] had indicated abrupt change in lattice parame-.

  19. Structural characterization of epitaxial LiFe_5O_8 thin films grown by chemical vapor deposition

    International Nuclear Information System (INIS)

    Loukya, B.; Negi, D.S.; Sahu, R.; Pachauri, N.; Gupta, A.; Datta, R.

    2016-01-01

    We report on detailed microstructural and atomic ordering characterization by transmission electron microscopy in epitaxial LiFe_5O_8 (LFO) thin films grown by chemical vapor deposition (CVD) on MgO (001) substrates. The experimental results of LFO thin films are compared with those for bulk LFO single crystal. Electron diffraction studies indicate weak long-range ordering in LFO (α-phase) thin films in comparison to bulk crystal where strong ordering is observed in optimally annealed samples. The degree of long-range ordering depends on the growth conditions and the thickness of the film. Annealing experiment along with diffraction study confirms the formation of α-Fe_2O_3 phase in some regions of the films. This suggests that under certain growth conditions γ-Fe_2O_3-like phase forms in some pockets in the as-grown LFO thin films that then convert to α-Fe_2O_3 on annealing. - Highlights: • Atomic ordering in LiFe_5O_8 bulk single crystal and epitaxial thin films. • Electron diffraction studies reveal different level of ordering in the system. • Formation of γ-Fe_2O_3 like phase has been observed.

  20. Optical properties of monodispersive FePt nanoparticle films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.J.; Lo, C.C.H. [Ames Laboratory, Iowa State University, Ames, IA 50011 (United States); Yu, A.C.C. [Sony Corporation, Sendai Technology Center, 3-4-1 Sakuragi, Miyagi 985-0842 (Japan); Fan, M. [Center for Sustainable Environmental Technologies, Iowa State University, Ames, IA 50011 (United States)

    2004-10-01

    The optical properties of monodispersive FePt nanoparticle films were investigated using spectroscopic ellipsometry in the energy range of 1.5 to 5.5 eV. The monodispersive FePt nanoparticle film was stabilized on a Si substrate by means of an organosilane coupling film, resulting in the formation of a (Si/SiO{sub 2}/APTS/FePt nanoparticles monolayer) structure. Multilayer optical models were employed to study the contribution of the FePt nanoparticles to the measured optical properties of the monodispersive FePt nanoparticle film, and to estimate the optical properties of the FePt nanoparticle layer. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Nanocrystalline Pd:NiFe2O4 thin films: A selective ethanol gas sensor

    Science.gov (United States)

    Rao, Pratibha; Godbole, R. V.; Bhagwat, Sunita

    2016-10-01

    In this work, Pd:NiFe2O4 thin films were investigated for the detection of reducing gases. These films were fabricated using spray pyrolysis technique and characterized using X-ray diffraction (XRD) to confirm the crystal structure. The surface morphology was studied using scanning electron microscopy (SEM). Magnetization measurements were carried out using SQUID VSM, which shows ferrimagnetic behavior of the samples. These thin film sensors were tested against methanol, ethanol, hydrogen sulfide and liquid petroleum gas, where they were found to be more selective to ethanol. The fabricated thin film sensors exhibited linear response signal for all the gases with concentrations up to 5 w/o Pd. Reduction in optimum operating temperature and enhancement in response was also observed. Pd:NiFe2O4 thin films exhibited faster response and recovery characteristic. These sensors have potential for industrial applications because of their long-term stability, low power requirement and low production cost.

  2. Crystallization in metglass: growth mechanism of crystals and radiation effects in Fe Ni P B

    International Nuclear Information System (INIS)

    Limoge, Y.; Barbu, A.

    1981-08-01

    Studying crystallization mechanisms and transport properties in amorphous metallic alloys we propose a model for systems wich are displaying eutectoid decomposition. Bringing together self diffusion, electron microscopy and electron irradiation experiments on a Fe Ni P B alloys we have shown that crystallization controlled by interfacial diffusion at the crystal surface can explain all the observed features of the experimental behaviour

  3. Epitaxial Growth of Permalloy Thin Films on MgO Single-Crystal Substrates

    International Nuclear Information System (INIS)

    Ohtake, Mitsuru; Tanaka, Takahiro; Matsubara, Katsuki; Futamoto, Masaaki; Kirino, Fumiyoshi

    2011-01-01

    Permalloy (Py: Ni - 20 at. % Fe) thin films were prepared on MgO single-crystal substrates of (100), (110), and (111) orientations by molecular beam epitaxy. Py crystals consisting of fcc(100) and hcp(112-bar 0) orientations epitaxially nucleate on MgO(100) substrates. With increasing the substrate temperature, the volume ratio of fcc(100) to hcp(112-bar 0) crystal increases. The metastable hcp(112-bar 0) structure transforms into more stable fcc(110) structure with increasing the film thickness. Py(110) fcc single-crystal films are obtained on MgO(110) substrates, whereas Py films epitaxially grow on MgO(111) substrates with two types of fcc(111) variants whose orientations are rotated around the film normal by 180 deg. each other. X-ray diffraction analysis indicates that the out-of-plane and the in-plane lattice spacings of these fcc-Py films agree within ±0.4% with the values of bulk fcc-Py crystal, suggesting that the strains in the films are very small. High-resolution transmission electron microscopy shows that periodical misfit dislocations are preferentially introduced in the films around the Py/MgO(100) and the Py/MgO(110) interfaces to reduce the lattice mismatches. The magnetic properties are considered to be reflecting the magnetocrystalline anisotropies of bulk fcc-Py and/or metastable hcp-Py crystals and the shape anisotropy caused by the surface undulations.

  4. Epitaxial Growth of Permalloy Thin Films on MgO Single-Crystal Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ohtake, Mitsuru; Tanaka, Takahiro; Matsubara, Katsuki; Futamoto, Masaaki [Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551 (Japan); Kirino, Fumiyoshi, E-mail: ohtake@futamoto.elect.chuo-u.ac.jp [Graduate School of Fine Arts, Tokyo National University of Fine Arts and Music, 12-8 Ueno-koen, Taito-ku, Tokyo 110-8714 (Japan)

    2011-07-06

    Permalloy (Py: Ni - 20 at. % Fe) thin films were prepared on MgO single-crystal substrates of (100), (110), and (111) orientations by molecular beam epitaxy. Py crystals consisting of fcc(100) and hcp(112-bar 0) orientations epitaxially nucleate on MgO(100) substrates. With increasing the substrate temperature, the volume ratio of fcc(100) to hcp(112-bar 0) crystal increases. The metastable hcp(112-bar 0) structure transforms into more stable fcc(110) structure with increasing the film thickness. Py(110){sub fcc} single-crystal films are obtained on MgO(110) substrates, whereas Py films epitaxially grow on MgO(111) substrates with two types of fcc(111) variants whose orientations are rotated around the film normal by 180 deg. each other. X-ray diffraction analysis indicates that the out-of-plane and the in-plane lattice spacings of these fcc-Py films agree within {+-}0.4% with the values of bulk fcc-Py crystal, suggesting that the strains in the films are very small. High-resolution transmission electron microscopy shows that periodical misfit dislocations are preferentially introduced in the films around the Py/MgO(100) and the Py/MgO(110) interfaces to reduce the lattice mismatches. The magnetic properties are considered to be reflecting the magnetocrystalline anisotropies of bulk fcc-Py and/or metastable hcp-Py crystals and the shape anisotropy caused by the surface undulations.

  5. 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.

  6. Ordering process of sputtered FePt films

    International Nuclear Information System (INIS)

    Takahashi, Y.K.; Ohnuma, M.; Hono, K.

    2003-01-01

    We have investigated the in situ ordering process of sputtered FePt thin films deposited on heated substrates at 300 deg. C with different thicknesses. The films thinner than 50 nm were composed of nanograins (∼5 nm) of disordered FePt phase. Recrystallization occurred when films were grown thicker than 100 nm, and transformation twins were observed in recrystallized grains, in which ordering to the L1 0 structure was confirmed

  7. Variable substrate temperature deposition of CoFeB film on Ta for manipulating the perpendicular coercive forces

    Science.gov (United States)

    Lakshmanan, Saravanan; Rao, Subha Krishna; Muthuvel, Manivel Raja; Chandrasekaran, Gopalakrishnan; Therese, Helen Annal

    2017-08-01

    Magnetization of Ta/CoFeB/Ta trilayer films with thick layer of CoFeB deposited under different substrate temperatures (Ts) via ultra-high vacuum DC sputtering technique has been measured with the applied magnetic field parallel and perpendicular to the plane of the film respectively to study the perpendicular coercive forces of the film. The samples were further analyzed for its structural, topological, morphological, and electrical transport properties. The core chemical states for the elements present in the CoFeB thin film were analyzed by XPS studies. Magnetization studies reveal the existence of perpendicular coercive forces in CoFeB films deposited only at certain temperatures such as RT, 450 °C, 475 °C and 500 °C. CoFeB film deposited at 475 °C exhibited a maximum coercivity of 315 Oe and a very low saturation magnetization (Ms) of 169 emu/cc in perpendicular direction. This pronounced effect in perpendicular coercive forces observed for CoFeB475 could be attributed to the effect of temperature in enhancing the crystallization of the film at the Ta/CoFeB interfaces. However at temperatures higher than 475 °C the destruction of the Ta/CoFeB interface due to intermixing of Ta and CoFeB results in the disappearance of magnetic anisotropy.

  8. High-coercivity FePt sputtered films

    International Nuclear Information System (INIS)

    Luong, N.H.; Hiep, V.V.; Hong, D.M.; Chau, N.; Linh, N.D.; Kurisu, M.; Anh, D.T.K.; Nakamoto, G.

    2005-01-01

    Fe 56 Pt 44 thin films have been prepared by RF magnetron sputtering on Si substrates. The substrate temperature was kept at 350 deg C. The X-ray diffraction patterns of as-deposited FePt films exhibited a disordered structure. Annealing of the films at 650-685 deg C for 1 h yielded an ordered L1 0 phase with FCT structure. The high value for coercivity H C of 17 kOe was obtained at room temperature for the 68 nm thick film annealed at 685 deg C. The hard magnetic properties as well as grain structure of the films strongly depend on the annealing conditions

  9. Magnetic and structural properties of NdFeB thin film prepared by step annealing

    International Nuclear Information System (INIS)

    Serrona, Leo K.E.B.; Sugimura, A.; Fujisaki, R.; Okuda, T.; Adachi, N.; Ohsato, H.; Sakamoto, I.; Nakanishi, A.; Motokawa, M.

    2003-01-01

    The crystallization of the amorphous phase into the tetragonal Nd 2 Fe 14 B (PHI) phase and the corresponding changes in magnetic properties have been examined by step annealing experiment using a 2 μm thick NdFeB film sample. Microstructural and magnetic analysis indicate that the film was magnetically soft as deposited with the coercivity H ciperp -1 and the remnant magnetization 4πM rperp -1 was developed and diffraction analysis showed evidence of PHI phase 002l peaks being aligned perpendicular to the film plane. At an optimum annealing temperature of 575 deg. C, the remnant magnetization of this anisotropic thin film is around 0.60 T with intrinsic coercivity of ∼1340 kA m -1 . Annealing the film sample at 200 deg. C≤T ann ≤750 deg. C showed variations in magnetic properties that were mostly due to the change in the perpendicular anisotropy. Based on 4πM sperpendicular values plotted against T ann , a dip in 4πM sperpendicular values was observed as T ann increased in the soft-to-hard magnetic characteristics transition region and rose as the hard crystalline phase started to form. The results show that the magnetic properties of the NdFeB film were slightly influenced by the presence of NdO, film surface roughening and the small increase in crystal size as a consequence of repeated heat treatment. At T ann ∼300 deg. C, the nominal saturation magnetization indicated a certain degree of weak perpendicular magnetic anisotropy in the film sample considered to be essential in the enhancement of coercivity in crystallized films

  10. Enhanced photovoltaic currents in strained Fe-doped LiNbO{sub 3} films

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Ryotaro [Division of Physics, Institute of Liberal Education, School of Medicine, Nihon University, 31-10, Ooyaguchi-kamicho, Itabashi-ku, Tokyo 173-8601 (Japan); Takahashi, Shusuke; Kitanaka, Yuuki; Oguchi, Takeshi; Noguchi, Yuji; Miyayama, Masaru [Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8654 (Japan)

    2015-12-15

    We investigate the impact of strain on photovoltaic current (J{sub z}) characteristics for iron-doped LiNbO{sub 3} (Fe-LN) under visible light illumination by thin-film experiments. The J{sub z} values are demonstrated to be dramatically enhanced for the film with a tensile strain along the P{sub s} direction, which is over 500 times as large as that of the bulk (strain-free) Fe-LN crystals. Density functional theory (DFT) calculations show that the tensile strain increases an off-center displacement of Fe{sup 2+} that is opposite to the P{sub s} direction. Our experimental and DFT study demonstrates that the control of the lattice strain is effective in enhancing the photovoltaic effect in the Fe-LN system. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Strength anomaly in B2 FeAl single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimi, K.; Hanada, S.; Yoo, M.H. [Oak Ridge National Lab., TN (United States); Matsumoto, N. [Tohoku Univ. (Japan). Graduate School

    1994-12-31

    Strength and deformation microstructure of B2 Fe-39 and 48%Al single crystals (composition given in atomic percent), which were fully annealed to remove frozen-in vacancies, have been investigated at temperatures between room temperature and 1073K. The hardness of as-homogenized Fe-48Al is higher than that of as-homogenized Fe-39Al while after additional annealing at 698K the hardness of Fe-48Al becomes lower than that of Fe-39Al. Fe-39Al single crystals slowly cooled after homogenizing at a high temperature were deformed in compression as a function of temperature and crystal orientation. A peak of yield strength appears around 0.5T{sub m} (T{sub m} = melting temperature). The orientation dependence of the critical resolved shear stress does not obey Schmid`s law even at room temperature and is quite different from that of b.c.c. metals and B2 intermetallics at low temperatures. At the peak temperature slip transition from <111>-type to <001>-type is found to occur macroscopically and microscopically, while it is observed in TEM that some of the [111] dislocations decompose into [101] and [010] on the (1096I) plane below the peak temperature. The physical sources for the positive temperature dependence of yield stress of B2 FeAl are discussed based on the obtained results.

  12. Magnetic and microstructural properties of thin NdFeB based films and nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Bommer, Lars; Goll, Dagmar [Max-Planck-Institut fuer Metallforschung, Stuttgart (Germany)

    2010-07-01

    The magnetic and microstructural properties of NdFeB and NdFeB/Fe thin films and nanostructures are presented. Samples with Cr buffer and protection layer (minimum thickness: d=50 nm) have been produced by ion beam sputtering at elevated temperatures (T{sub s}=700 C) using Al{sub 2}O{sub 3} and MgO(001) single crystal substrates. Films deposited on Al{sub 2}O{sub 3} substrates show c-axis growth in out-of-plane direction down to thicknesses of the NdFeB film of d=10 nm with coercivities up to {mu}{sub 0}H{sub c}=1 T. The texture of films deposited on MgO(001) substrates is less pronounced and films below d=20 nm show no hard magnetic behavior. For comparison, films were deposited at room temperature on Al{sub 2}O{sub 3} and MgO(001) followed by post-annealing in Ar atmosphere (T{sub pa}=525-650 C) leading to coercivities as high as {mu}{sub 0}H{sub c}=1.2 T but with isotropic behavior. By TEM images the grain structure of the NdFeB samples is studied. Bilayers of NdFeB (d=50 nm) and Fe (d=0-20 nm) show fully exchange coupled behavior. From the temperature dependence of the coercivity the microstructural parameters of all samples have been determined. Furthermore NdFeB periodical patterns were produced by means of electron beam lithography with dot sizes of 1000 nm and 500 nm, respectively.

  13. Crystallization of amorphous Fe78Si9B13 alloy

    International Nuclear Information System (INIS)

    Jakubczyk, E; Krajczyk, A; Jakubczyk, M

    2007-01-01

    The crystallization process of Fe 78 Si 9 B 13 metallic glass was investigated by DSC, X-ray diffraction, electrical resistivity, Hall effect and TEM methods. The investigations proved two-stages crystallization. By means of non-isothermal DSC experiments the activation energy and the Avrami exponent were determined for both stages. The created phases: α-Fe(Si) and (Fe,Si) 2 B were identified on the basis of X-ray and TEM investigations. However, TEM observations showed also a little amount of the FeB 49 phase as well as some rest of the amorphous phase. The electrical and Hall resistivities decrease abruptly after the creation of the phases out of the amorphous matrix

  14. Si/Fe flux ratio influence on growth and physical properties of polycrystalline β-FeSi2 thin films on Si(100) surface

    Science.gov (United States)

    Tarasov, I. A.; Visotin, M. A.; Aleksandrovsky, A. S.; Kosyrev, N. N.; Yakovlev, I. A.; Molokeev, M. S.; Lukyanenko, A. V.; Krylov, A. S.; Fedorov, A. S.; Varnakov, S. N.; Ovchinnikov, S. G.

    2017-10-01

    This work investigates the Si/Fe flux ratio (2 and 0.34) influence on the growth of β-FeSi2 polycrystalline thin films on Si(100) substrate at 630 °C. Lattice deformations for the films obtained are confirmed by X-ray diffraction analysis (XRD). The volume unit cell deviation from that of β-FeSi2 single crystal are 1.99% and 1.1% for Si/Fe =2 and Si/Fe =0.34, respectively. Absorption measurements show that the indirect transition ( 0.704 eV) of the Si/Fe =0.34 sample changes to the direct transition with a bandgap value of 0.816 eV for the sample prepared at Si/Fe =2. The absorption spectrum of the Si/Fe =0.34 sample exhibits an additional peak located below the bandgap energy value with the absorption maximum of 0.36 eV. Surface magneto-optic Kerr effect (SMOKE) measurements detect the ferromagnetic behavior of the β-FeSi2 polycrystalline films grown at Si/Fe =0.34 at T=10 K, but no ferromagnetism was observed in the samples grown at Si/Fe =2. Theoretical calculations refute that the cell deformation can cause the emergence of magnetization and argue that the origin of the ferromagnetism, as well as the lower absorption peak, is β-FeSi2 stoichiometry deviations. Raman spectroscopy measurements evidence that the film obtained at Si/Fe flux ratio equal to 0.34 has the better crystallinity than the Si/Fe =2 sample.

  15. X-ray characteristic temperature of Fe-Ni alloys with different crystal lattices

    International Nuclear Information System (INIS)

    Krasnikova, G.N.; Ushakov, A.I.; Kazakov, V.G.; Bochkarev, V.F.; Gorovoj, A.M.

    1978-01-01

    Investigated has been the temperature dependence of the thermal expansion coefficient and the characteristic Debye temperature of the ferronickel films, having a body-centered (cubic) and a face-centered (cubic) lattice. In case of the body-centered lattice films the tests have been staged in the 100-200 deg C range, and in case of the face c.entered lattice films - in the 20-300 deg C range. The study of temperature dependence of the thermal expansion coefficient has revealed that a non-linear growth of the thermal expansion coefficient occurs in α-phase samples when approaching the phase transition temperature. The phase transition in the Invar composition Fe-Ni films is conductive to a considerable variation of the Debye temperature. Approaching the phase transition temperature, the crystal lattice dynamic characteristics vary

  16. Lasing in liquid crystal thin films

    Energy Technology Data Exchange (ETDEWEB)

    Palto, S. P. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)], E-mail: palto@online.ru

    2006-09-15

    A lasing condition is formulated in matrix form for optically anisotropic thin films. Lasing behavior of liquid-crystal slabs is analyzed. In particular, it is shown that if the spatial extent of a liquid crystal slab is much larger than its thickness, then laser emission is feasible not only along the normal to the slab, but also in the entire angular sector. The generated laser light can be observed experimentally as a spot or as concentric rings on a screen. The lowest lasing threshold corresponds to in-plane sliding modes leaking into the substrate. The feedback required for lasing is provided by reflection from the interfaces, rather than edges, of the liquid-crystal slab operating as a planar Fabry-Perot cavity. For cholesteric liquid crystals, it is shown that energy loss to the sliding modes leaking into the substrates and escaping through their edges is a key factor that limits the efficiency of band-edge emission along the normal to the slab.

  17. NdFeB thick films prepared by tape casting

    International Nuclear Information System (INIS)

    Pawlowski, B.; Schwarzer, S.; Rahmig, A.; Toepfer, J.

    2003-01-01

    NdFeB films of thickness between 100 and 800 μm were prepared by tape casting of a slurry containing 84-95 wt% of commercial NdFeB powder (MQP-B, -Q and -S). After curing the flexible green tapes at 120 deg. C non-porous magnetic films are obtained. The remanence of the films is in the range of 350-450 mT and the coercivity is between 300 and 800 kA/m depending on the type of MQP powder used. The magnetic properties of the films are discussed in relation to film composition and type of magnetic material. For MEMS applications the thick films are magnetized with a multi-pole stripe pattern with 1 mm pole pitch. The induction at the surface of the films was measured with a Hall probe and compared to theoretical calculations. The results indicate that the films are completely magnetized regardless of the film thickness. Tape-casted NdFeB thick films are promising candidates for applications in micro-systems or actuators. Miniaturization of the magnet components is one of the key issues in the development of electromagnetic micro-systems, thus creating a need for replacement of small sintered magnets by magnetic thick film components. Other applications include encoders

  18. Electroplated Fe-Co-Ni films prepared from deep-eutectic-solvent-based plating baths

    Directory of Open Access Journals (Sweden)

    Takeshi Yanai

    2016-05-01

    Full Text Available We fabricated soft magnetic films from DES-based plating baths, and investigated magnetic properties of the plated films. The plating baths were obtained by stirring the mixture of choline chloride, ethylene glycol, FeCl2 ⋅ 4H2O, NiCl2 ⋅ 6H2O and CoCl2 ⋅ 6H2O. The composition of the electroplated film depended on the amount of the reagent in the plating bath, and we consequently obtained the films with various composition. The current efficiency of the plating process shows high values (> 88 % in the wide composition range. The soft magnetic films with low coercivity were obtained at the Fe compositions of ≈ 30 at.% and > 80 at.%, and we found that low coercivity could be realized by the control of the film composition. We also found that the Fe-rich films prepared from DES-based plating bath have some advantages as a soft magnetic phase for a nanocomposite magnet due to their high saturation magnetization and very fine crystal structure.

  19. Electrodeposition and characterization of nanocrystalline CoNiFe films

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.; Wang, Q.P. [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Cai, C. [School of Chemistry and chemical engineering, Ningxia University, Yinchuan 750021 (China); Yuan, Y.N. [Department of Materials and Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Cao, F.H. [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Zhang, Z., E-mail: eaglezzy@zjuem.zju.edu.cn [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Zhang, J.Q. [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); State Key Laboratory for Corrosion and Protection of Metals, Shenyang 110016 (China)

    2012-02-29

    Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} films have been fabricated using cyclic voltammetry technique from the solutions containing sulfate, then characterized by scanning electron microscopy, X-ray diffraction and vibrating sample magnetometer. Meanwhile, Electrochemical Impedance Spectroscopy technique has been employed to probe into the nucleation/growth behavior of Co{sub 45}Ni{sub 10}Fe{sub 24} films. The results show that, the obtained Co{sub 45}Ni{sub 10}Fe{sub 24} film possesses low coercivity of 973.3 A/m and high saturation magnetic flux density of 1.59 Multiplication-Sign 10{sup 5} A/m. Under the experimental conditions, the nucleation/growth process of Co{sub 45}Ni{sub 10}Fe{sub 24} films is mainly under activation control. With the increase of the applied cathodic potential bias, the charge transfer resistance for CoNiFe deposition decreases exponentially. - Highlights: Black-Right-Pointing-Pointer Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} film is obtained using cyclic voltammetry technique. Black-Right-Pointing-Pointer Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} possesses low coercivity of 973.3 A/m. Black-Right-Pointing-Pointer Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} possesses high saturation magnetic flux density. Black-Right-Pointing-Pointer The nucleation/growth process of CoNiFe films is mainly under activation control. Black-Right-Pointing-Pointer The charge transfer resistance for CoNiFe deposition decreases exponentially.

  20. Crystallization characteristics of amorphous alloys of FeZr

    International Nuclear Information System (INIS)

    Rozhan, M. Idrus; Grundy, P.J.

    1993-01-01

    The crystallization characteristics of sputter-deposited amorphous alloys of Fe 100-x Zr x prepared at zirconium concentrations between 9 and 89 at.% was investigated. The transformation of the alloys from the amorphous to the crystalline state has been examined by thermal analysis, electrical resistance and X-ray diffraction. The crystallization temperatures were determined by differential scanning calorimetry (DSC) and electrical resistance as a function of temperature. The final phases were determined by X-ray diffraction. The activation energies were calculated from the Kissinger plots and the heats of crystallization were calculated and correlations between the thermal analysis and the resistance results are presented

  1. Multi-jump magnetic switching in ion-beam sputtered amorphous Co20Fe60B20 thin films

    International Nuclear Information System (INIS)

    Raju, M.; Chaudhary, Sujeet; Pandya, D. K.

    2013-01-01

    Unconventional multi-jump magnetization reversal and significant in-plane uniaxial magnetic anisotropy (UMA) in the ion-beam sputtered amorphous Co 20 Fe 60 B 20 (5–75 nm) thin films grown on Si/amorphous SiO 2 are reported. While such multi-jump behavior is observed in CoFeB(10 nm) film when the magnetic field is applied at 10°–20° away from the easy-axis, the same is observed in CoFeB(12.5 nm) film when the magnetic field is 45°–55° away from easy-axis. Unlike the previous reports of multi-jump switching in epitaxial films, their observance in the present case of amorphous CoFeB is remarkable. This multi-jump switching is found to disappear when the films are crystallized by annealing at 420 °C. The deposition geometry and the energy of the sputtered species appear to intrinsically induce a kind of bond orientation anisotropy in the films, which leads to the UMA in the as-grown amorphous CoFeB films. Exploitation of such multi-jump switching in amorphous CoFeB thin films could be of technological significance because of their applications in spintronic devices

  2. Co{sub 100−x}Fe{sub x} magnetic thick films prepared by electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Aguirre, M. del C., E-mail: carmenaguirre@famaf.unc.edu.ar [Instituto de Física Enrique Gaviola-Conicet-Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba (Argentina); Farías, E. [Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba (Argentina); Abraham, J.; Urreta, S.E. [Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba (Argentina)

    2015-04-05

    Highlights: • Low iron containing films are compact, with rounded, relatively uniform surfaces. • Larger Fe contents exhibit nanowall networks covering the surface. • Coercivity in the out of plane configuration is larger than in the easy axis direction. • Co-rich films nucleate and grow by a 3DP diffusion controlled mechanism. • For equiatomic Fe{sub 50}Co{sub 50} films, nucleation tends to become instantaneous. - Abstract: Co–Fe films are grown onto plane pre-treated Cu foils; the effects of the alloy composition on the morphology and the crystal texture of the electrodeposited films and their anisotropic magnetic hysteresis properties are explored. Nucleation and crystallization mechanisms in these Co-rich layers are also investigated with pulse-reverse plating techniques, using the first cathodic pulse current–time transients. In the diffusion controlled regime the deposition mechanism is found to involve progressive nucleation with three-dimensional (3D) growth, except for the equiatomic Fe{sub 50}Co{sub 50} solution where nucleation tends to become instantaneous. The different morphologies and size scales observed are described and correlated with coercivity. The films are electrodeposited onto electrochemically pre-treated Cu substrates from feeds of nominal Fe/Co mol ratios between 0/100 and 50/50. The composition of the deposited layers, as determined by energy dispersive X-ray spectroscopy, are quite close to the nominal values. Cyclic voltammetry determinations exhibit only a single reduction process on the cathode, indicating that a unique (Co{sub 100−x}Fe{sub x}) phase grows. Depending on composition and on the substrate pre-treatment, these layers exhibit textures with features of different sizes. X ray diffraction patterns indicate that the nanostructures with Fe contents above 20 at.% crystallize in a body-centered cubic cell, while samples with Fe contents below this value are fcc. Regarding the effect of composition on the

  3. Skyrmions and Novel Spin Textures in FeGe Thin Films and Artificial B20 Heterostructures

    Science.gov (United States)

    Ahmed, Adam Saied

    Skyrmions are magnetic spin textures that have a non-zero topological winding number associated with them. They have attracted much interest recently since they can be as small as 1 nm and could be the next generation of magnetic memory and logic. First, we grow epitaxial films of FeGe by molecular beam epitaxy and characterized the skyrmion properties. This had led us to image skyrmions in real-space with Lorentz transmission electron microscopy for the first time in the United States. Next, from an extensive series of thin and thick films, we have experimentally shown the existence of a magnetic surface state in FeGe and, consequently, any skyrmion material for the first time. Complementary theoretical calculations supported the existence of chiral bobbers--a surface state only predicted in 2015. Next, we fabricated for the first time a new class of skyrmion materials: B20 superlattices. These novel heterostructures of [FeGe/MnGe/CrGe] have now opened the door for tunable skyrmion systems with both Dresselhaus and Rashba Dzyaloshinskii-Moriya interactions. Additionally, we perform resonant soft x-ray scattering to image magnetic spin textures in reciprocal space for FeGe thin films in transmission. We have accomplished the removal of substrate and left an isolated single-crystal FeGe film. Lastly, SrO is grown on graphene as a crystalline, atomically smooth, and pinhole free tunnel barrier for spin injection.

  4. Effect of annealing on the magnetic properties and microstructure of NdFeB/Tb multilayered films

    Energy Technology Data Exchange (ETDEWEB)

    Li, D S; Suzuki, S; Liu, W F; Horikawa, T; Machida, K [Center for Advanced Science and Innovation, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)], E-mail: machida@casi.osaka-u.ac.jp

    2009-02-01

    The magnetic properties of NdFeB/Tb multilayered films annealed at 773-1273K were investigated by evaluating the effect of Tb spacer layer and comparing them with those of NdFeB single layered films. The as-deposited NdFeB/Tb film with a amorphous structure was crystallized at the higher annealing temperature than 923K and Nd-rich phases were formed at 1073 K, meanwhile the coercivity increased substantially. By observations of the microstructure, Tb element was found to diffuse into the Nd-rich phases to form a Tb-enriched phase around the Nd{sub 2}Fe{sub 14}B primary phase particles in the multilayered films.

  5. Effect of annealing on the magnetic properties and microstructure of NdFeB/Tb multilayered films

    International Nuclear Information System (INIS)

    Li, D S; Suzuki, S; Liu, W F; Horikawa, T; Machida, K

    2009-01-01

    The magnetic properties of NdFeB/Tb multilayered films annealed at 773-1273K were investigated by evaluating the effect of Tb spacer layer and comparing them with those of NdFeB single layered films. The as-deposited NdFeB/Tb film with a amorphous structure was crystallized at the higher annealing temperature than 923K and Nd-rich phases were formed at 1073 K, meanwhile the coercivity increased substantially. By observations of the microstructure, Tb element was found to diffuse into the Nd-rich phases to form a Tb-enriched phase around the Nd 2 Fe 14 B primary phase particles in the multilayered films.

  6. Influence of microstructural change of the interface between Nd2Fe14B and Nd-O phases on coercivity of Nd-Fe-B films by oxidation and subsequent low-temperature annealing

    International Nuclear Information System (INIS)

    Matsuura, Masashi; Tezuka, Nobuki; Sugimoto, Satoshi; Goto, Ryota

    2011-01-01

    This study provides the influence of microstructural change of the interface between Nd 2 Fe 14 B and Nd-O phases on coercivity of Nd-Fe-B thin films during annealing at low temperature (∼350 deg. C). All films were prepared by using ultra high vacuum (UHV) magnetron sputtering, and the Nd-Fe-B layer was oxidized under Ar gas atmosphere (O 2 content; ∼2 Vol.ppm). Then, the films were annealed at 250-350 deg. C under UHV condition. After oxidation, the coercivity of Nd-Fe-B film decreased to around 40% of the coercivity of as-deposited Nd-Fe-B film. The Nd-rich phase changed from α-Nd to amorphous Nd(-O), and the interface of Nd 2 Fe 14 B/Nd(-O) became rough. In the Nd-Fe-B films oxidized and subsequent annealed at 350 deg. C, the coercivity decreased to around 20%. In the films, poly crystalline hcp Nd 2 O 3 phase crystallized in Nd-rich phase, and there were some steps at the surface of Nd 2 Fe 14 B phase contacting with hcp Nd 2 O 3 phase. Regardless of crystal orientation of Nd 2 Fe 14 B, the microstructural changes of the interface described above were observed.

  7. The effects of Fe2O3 nanoparticles on MgB2 superconducting thin films

    International Nuclear Information System (INIS)

    Koparan, E.T.; Sidorenko, A.; Yanmaz, E.

    2013-01-01

    Full text: Since the discovery of superconductivity in binary MgB 2 compounds, extensive studies have been carried out because of its excellent properties for technological applications, such as high transition temperature (T c = 39 K), high upper critical field (H c2 ), high critical current density (J c ). Thin films are important for fundamental research as well as technological applications of any functional materials. Technological applications primarily depend on critical current density. The strong field dependence of J c for MgB 2 necessitates an enhancement in flux pinning performance in order to improve values in high magnetic fields. An effective way to improve the flux pinning is to introduce flux pinning centers into MgB 2 through a dopant having size comparable to the coherence length of MgB 2 . In this study, MgB 2 film with a thickness of about 600 nm was deposited on the MgO (100) single crystal substrate using a 'two-step' synthesis technique. Firstly, deposition of boron thin film was carried out by rf magnetron sputtering on MgO substrates and followed by a post deposition annealing at 850 degrees Celsius in magnesium vapour. In order to investigate the effect of Fe 2 O 3 nanoparticles on the structural and magnetic properties of films, MgB 2 films were coated with different concentrations of Fe 2 O 3 nanoparticles by a spin coating process. The effects of different concentrations of ferromagnetic Fe 2 O 3 nanoparticles on superconducting properties of obtained films were carried out by using structural (XRD, SEM, AFM), electrical (R-T) and magnetization (M-H, M-T and AC Susceptibility) measurements. It was calculated that anisotropic coefficient was about γ = 1.2 and coherence length of 5 nm for the uncoated film. As a result of coherence length, the appropriate diameters of Fe 2 O 3 nanoparticles were found to be 10 nm, indicating that these nanoparticles served as the pinning centers. Based on the data obtained from this study, it can be

  8. Evidence of Room Temperature Ferromagnetism Due to Oxygen Vacancies in (In1- x Fe x )2O3 Thin Films

    Science.gov (United States)

    Chakraborty, Deepannita; Munuswamy, Kuppan; Shaik, Kaleemulla; Nasina, Madhusudhana Rao; Dugasani, Sreekantha Reddy; Inturu, Omkaram

    2018-03-01

    Iron substituted indium oxide (In1- x Fe x )2O3 thin films at x = 0.00, 0.03, 0.05 and 0.07 were coated onto Corning 7059 glass substrates using the electron beam evaporation technique followed by annealing at different temperatures. The prepared thin films were subjected to different characterization techniques to study their structural, optical and magnetic properties. The structural properties of the thin films were studied using x-ray diffractometry (XRD). From the XRD results it was found that the films were crystallized in cubic structure, and no change in crystal structure was observed with annealing temperature. No secondary phases related to iron were observed from the XRD profiles. The chemical composition and surface morphology of the films were examined by field emission scanning electron microscope (FE-SEM) attached with energy dispersive analysis of x-ray (EDAX). The valence state of the elements were studied by x-ray photoelectron spectroscopy (XPS) and found that the indium, iron and oxygen were in In+3, Fe+3 and O-2 states. From the data, the band gap of the (In1- x Fe x )2O3 thin films were calculated and it increased with increase of annealing temperature. The magnetic properties of the films were studied at room temperature by vibrating sample magnetometer (VSM). The films exhibited ferromagnetism at room temperature.

  9. Variable substrate temperature deposition of CoFeB film on Ta for manipulating the perpendicular coercive forces

    Energy Technology Data Exchange (ETDEWEB)

    Lakshmanan, Saravanan; Rao, Subha Krishna [Nanotechnology Research Centre, SRM University, Kattankulathur, Chennai 603203 (India); Muthuvel, Manivel Raja [Defence Metallurgical Research Laboratory (DMRL), Hyderabad 500058 (India); Chandrasekaran, Gopalakrishnan [Nanotechnology Research Centre, SRM University, Kattankulathur, Chennai 603203 (India); Therese, Helen Annal, E-mail: helen.a@ktr.srmuniv.ac.in [Nanotechnology Research Centre, SRM University, Kattankulathur, Chennai 603203 (India)

    2017-08-01

    Highlights: • Ta/CoFeB(50 nm)/Ta thin films were deposited at various substrate temperatures (T{sub s}). • CoFeB films deposited at T{sub s} such as RT, 450 °C, 475 °C and 500 °C exhibited perpendicular coercivity. • CoFeB deposited at 475 °C displayed a higher coercivity of 315 Oe and a low M{sub s} of 169 emu/cc. • The enhanced crystallization of CoFeB at the Ta/CoFeB interface results in higher H{sub c} (⟂). - Abstract: Magnetization of Ta/CoFeB/Ta trilayer films with thick layer of CoFeB deposited under different substrate temperatures (T{sub s}) via ultra-high vacuum DC sputtering technique has been measured with the applied magnetic field parallel and perpendicular to the plane of the film respectively to study the perpendicular coercive forces of the film. The samples were further analyzed for its structural, topological, morphological, and electrical transport properties. The core chemical states for the elements present in the CoFeB thin film were analyzed by XPS studies. Magnetization studies reveal the existence of perpendicular coercive forces in CoFeB films deposited only at certain temperatures such as RT, 450 °C, 475 °C and 500 °C. CoFeB film deposited at 475 °C exhibited a maximum coercivity of 315 Oe and a very low saturation magnetization (M{sub s}) of 169 emu/cc in perpendicular direction. This pronounced effect in perpendicular coercive forces observed for CoFeB475 could be attributed to the effect of temperature in enhancing the crystallization of the film at the Ta/CoFeB interfaces. However at temperatures higher than 475 °C the destruction of the Ta/CoFeB interface due to intermixing of Ta and CoFeB results in the disappearance of magnetic anisotropy.

  10. Magnetic and thermal properties of amorphous TbFeCo alloy films

    Science.gov (United States)

    Wang, Ke; Dong, Shuo; Huang, Ya; Qiu, Yuzhen

    2017-07-01

    Amorphous TbFeCo material with perpendicular magnetic anisotropy is currently attracting more attention for potential applications in spintronic devices and logic memories. We systematically investigate magnetic, structural, thermal, optical and electrical properties of TbFeCo alloy films. It shows out-of-plane easy axis of the films turns into in-plane orientation after annealing. Significant increase in saturation magnetization in the temperature range between 400 and 450 °C is revealed by thermomagnetic measurements. The occurrence of crystallization and oxidation at high temperatures is confirmed by X-ray diffraction measurements. Pronounced changes in optical reflectance and sheet resistance are observed with temperature, in line with structural relaxation and change. The activation barriers for crystallization and oxidation are determined to be 1.01 eV and 0.83 eV, respectively, for FeCo-rich and Tb-rich samples. Better thermal stability against crystallization and oxidation is demonstrated in the FeCo-rich sample than the Tb-rich type. Our results provide some useful information for the alloy used in device fabrication.

  11. β-FeSi2 films prepared on 6H-SiC substrates by magnetron sputtering

    Science.gov (United States)

    Hong, Li; Hongbin, Pu; Chunlei, Zheng; Zhiming, Chen

    2015-06-01

    β-FeSi2 thin films have been successfully prepared by magnetron sputtering and post rapid thermal annealing method on 6H-SiC (0001) substrates using a FeSi2 target and a Si target. X-ray diffraction (XRD) and Raman spectroscopy are applied to analyze the formation of β-FeSi2 films. XRD spectra reveal that the amorphous FeSi2 films are transformed to β-FeSi2 phase as the annealing temperature is increased from 500 to 900 °C for 5 min and the optimal annealing temperature is 900 °C. The formation of β-FeSi2 is also confirmed by Raman spectroscopy. Scanning electron microscope (SEM) observations indicate that the film is flat, relatively compact and the interface between β-FeSi2 and 6H-SiC is clear. Atomic force microscope (AFM) measurements demonstrate that the surface roughness confirmed by the root mean square (RMS) of the β-FeSi2 film is 0.87 nm. Near-infrared spectrophotometer observation shows that the absorption coefficient is of the order of 105 cm-1 and the optical band-gap of the β-FeSi2 film is 0.88 eV. The β-FeSi2 film with high crystal quality is fabricated by co-sputtering a FeSi2 target and a Si target for 60 min and annealing at 900 °C for 5 min. Project supported by the National Natural Science Foundation of China (No. 51177134) and the Natural Science Basic Research Plan in Shaanxi Province of China (No. 2015JM6286).

  12. Crystallization behavior and magnetic properties in High Fe content FeBCSiCu alloy system

    Energy Technology Data Exchange (ETDEWEB)

    Fan, X.D., E-mail: fanxd@seu.edu.cn; Shen, B.L., E-mail: blshen@seu.edu.cn

    2015-07-01

    High Fe content FeBCSiCu nanocrystalline alloys are prepared by annealing melt-spun amorphous ribbons with aim at increasing saturation magnetic flux density. Microstructures identified by XRD and TEM reveal that Cu addition inhibits the surface crystallization of Fe{sub 86}B{sub 7}C{sub 7} alloy and improve its glass-forming ability. Activation energy of crystallization calculated by Kissinger's equation indicates that both Cu and Si addition promotes the precipitation of α-Fe phase and improves the thermal stability. VSM and DC B–H loop tracer measurements show that the Fe{sub 85.5}B{sub 7}C{sub 6}Si{sub 1}Cu{sub 0.5} nanocrystalline alloy exhibits high saturation magnetic flux density of 1.8 T and low coercivity of 10 A/m, respectively. AC properties measured by AC B–H analyzer show this alloy exhibits low core loss of 0.35 W/kg at 1 T at 50 Hz. Low material cost and convenient productivity make the Fe{sub 85.5}B{sub 7}C{sub 6}Si{sub 1}Cu{sub 0.5} nanocrystalline alloy an economical application in industry. - Highlights: • Cu addition inhibits the surface crystallization and improves the GFA. • The competitive formation of Fe{sub 3}C and α-Fe phase impedes the devitrification. • Fe{sub 85.5}B{sub 7}C{sub 6}Si{sub 1}Cu{sub 0.5} nanocrystalline alloy exhibits excellent magnetic properties. • The alloy system has an economical advantage and convenient productivity.

  13. High Temperature Magnetic Properties of Indirect Exchange Spring FePt/M(Cu,C/Fe Trilayer Thin Films

    Directory of Open Access Journals (Sweden)

    Anabil Gayen

    2013-01-01

    Full Text Available We report the investigation of temperature dependent magnetic properties of FePt and FePt(30/M(Cu,C/Fe(5 trilayer thin films prepared by using magnetron sputtering technique at ambient temperature and postannealed at different temperatures. L10 ordering, hard magnetic properties, and thermal stability of FePt films are improved with increasing postannealing temperature. In FePt/M/Fe trilayer, the formation of interlayer exchange coupling between magnetic layers depends on interlayer materials and interface morphology. In FePt/C/Fe trilayer, when the C interlayer thickness was about 0.5 nm, a strong interlayer exchange coupling between hard and soft layers was achieved, and saturation magnetization was enhanced considerably after using interlayer exchange coupling with Fe. In addition, incoherent magnetization reversal process observed in FePt/Fe films changes into coherent switching process in FePt/C/Fe films giving rise to a single hysteresis loop. High temperature magnetic studies up to 573 K reveal that the effective reduction in the coercivity decreases largely from 34 Oe/K for FePt/Fe film to 13 Oe/K for FePt/C(0.5/Fe film demonstrating that the interlayer exchange coupling seems to be a promising approach to improve the stability of hard magnetic properties at high temperatures, which is suitable for high-performance magnets and thermally assisted magnetic recording media.

  14. Experimental studies on the electronic structure of pyrite FeS2 films prepared by thermally sulfurizing iron films

    International Nuclear Information System (INIS)

    Zhang Hui; Wang Baoyi; Zhang Rengang; Zhang Zhe; Wei Long; Qian Haijie; Su Run; Kui Rexi

    2006-01-01

    Pyrite FeS 2 films have been prepared by thermally sulfurizing iron films deposited by magnetron sputtering. The electronic structures were studies by X-ray absorption near edge structure and X-ray photoemission spectrum. The results show that an S 3p valence band with relatively higher intensity compared to the calculation exists in 2-10 eV range and a high density below the Fermi level of Fe 3d states were detected. A second gap of 2.8 eV in the unoccupied density of states was found above the conduction band which was 2.4 eV by experimentally calculation. The difference between t 2g and e g which were formed in an octahedral crystal field was computed to be 2.1 eV. (authors)

  15. Carbon dioxide and water adsorption on highly epitaxial Delafossite CuFeO2 thin film

    Science.gov (United States)

    Rojas, S.; Joshi, T.; Borisov, P.; Sarabia, M.; Lederman, D.; Cabrera, A. L.

    2015-03-01

    Thermal programmed desorption (TPD) of CO2 and H2O from a 200 nm thick CuFeO2 Delafossite surface was performed in a standard UHV chamber, The CuFeO2 thin film grown using Pulsed Laser Deposition (PLD) over an Al2O3 (0001) substrate with controlled O2 atmosphere resulted with highly epitaxial crystal structure. The adsorption/desorption of CO2 and H2O process was also monitored with X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). Our results revealed that carbon dioxide interacts with CuFeO2 forming Fe carbonates compounds on its surface. Hydroxides were also formed on the surface due to water presence. Using TPD data, Arrhenius plots for CO2 and water desorption were done and activation energy for desorption was obtained. Funds FONDECyT 1130372; Thanks to P. Ferrari.

  16. Development of FeNiMoB thin film materials for microfabricated magnetoelastic sensors

    KAUST Repository

    Liang, Cai; Gooneratne, Chinthaka; Cha, Dong Kyu; Chen, Long; Gianchandani, Yogesh; Kosel, Jü rgen

    2012-01-01

    MetglasTM 2826MB foils of 25–30 μm thickness with the composition of Fe40Ni38Mo4B18 have been used for magnetoelastic sensors in various applications over many years. This work is directed at the investigation of ∼3 μm thick iron-nickel-molybdenum-boron (FeNiMoB) thin films that are intended for integrated microsystems. The films are deposited on Si substrate by co-sputtering of iron-nickel (FeNi), molybdenum(Mo), and boron (B) targets. The results show that dopants of Mo and B can significantly change the microstructure and magnetic properties of FeNi materials. When FeNi is doped with only Mo its crystal structure changes from polycrystalline to amorphous with the increase of dopant concentration; the transition point is found at about 10 at. % of Mo content. A significant change in anisotropic magneticproperties of FeNi is also observed as the Modopant level increases. The coercivity of FeNi filmsdoped with Mo decreases to a value less than one third of the value without dopant.Doping the FeNi with B together with Mo considerably decreases the value of coercivity and the out-of-plane magnetic anisotropyproperties, and it also greatly changes the microstructure of the material. In addition, doping B to FeNiMo remarkably reduces the remanence of the material. The filmmaterial that is fabricated using an optimized process is magnetically as soft as amorphous MetglasTM 2826MB with a coercivity of less than 40 Am−1. The findings of this study provide us a better understanding of the effects of the compositions and microstructure of FeNiMoB thin filmmaterials on their magnetic properties.

  17. Development of FeNiMoB thin film materials for microfabricated magnetoelastic sensors

    KAUST Repository

    Liang, Cai

    2012-12-07

    MetglasTM 2826MB foils of 25–30 μm thickness with the composition of Fe40Ni38Mo4B18 have been used for magnetoelastic sensors in various applications over many years. This work is directed at the investigation of ∼3 μm thick iron-nickel-molybdenum-boron (FeNiMoB) thin films that are intended for integrated microsystems. The films are deposited on Si substrate by co-sputtering of iron-nickel (FeNi), molybdenum(Mo), and boron (B) targets. The results show that dopants of Mo and B can significantly change the microstructure and magnetic properties of FeNi materials. When FeNi is doped with only Mo its crystal structure changes from polycrystalline to amorphous with the increase of dopant concentration; the transition point is found at about 10 at. % of Mo content. A significant change in anisotropic magneticproperties of FeNi is also observed as the Modopant level increases. The coercivity of FeNi filmsdoped with Mo decreases to a value less than one third of the value without dopant.Doping the FeNi with B together with Mo considerably decreases the value of coercivity and the out-of-plane magnetic anisotropyproperties, and it also greatly changes the microstructure of the material. In addition, doping B to FeNiMo remarkably reduces the remanence of the material. The filmmaterial that is fabricated using an optimized process is magnetically as soft as amorphous MetglasTM 2826MB with a coercivity of less than 40 Am−1. The findings of this study provide us a better understanding of the effects of the compositions and microstructure of FeNiMoB thin filmmaterials on their magnetic properties.

  18. Crystal structure and crystal growth of the polar ferrimagnet CaBaFe4O7

    Science.gov (United States)

    Perry, R. S.; Kurebayashi, H.; Gibbs, A.; Gutmann, M. J.

    2018-05-01

    Magnetic materials are a cornerstone for developing spintronic devices for the transport of information via magnetic excitations. To date, relatively few materials have been investigated for the purpose of spin transport, mostly due to the paucity of suitable candidates as these materials are often chemically complex and difficult to synthesize. We present the crystal growth and a structure solution on the high-temperature crystal structure of the layered, polar ferrimagnet CaBaFe4O7 , which is a possible new contender for spintronics research. The space group is identified as P 3 by refinement of single crystal and powder neutron diffraction data. At 400 K, the trigonal lattice parameters are a =11.0114 (11 )Å and c =10.330 (3 )Å . The structure is similar to the low-temperature phase with alternating layers of triangular and Kagome-arranged Fe-O tetrahedra. We also present details of the crystal growth by traveling solvent method.

  19. BiFeO3 epitaxial thin films and devices: past, present and future

    Science.gov (United States)

    Sando, D.; Barthélémy, A.; Bibes, M.

    2014-11-01

    The celebrated renaissance of the multiferroics family over the past ten years has also been that of its most paradigmatic member, bismuth ferrite (BiFeO3). Known since the 1960s to be a high temperature antiferromagnet and since the 1970s to be ferroelectric, BiFeO3 only had its bulk ferroic properties clarified in the mid-2000s. It is however the fabrication of BiFeO3 thin films and their integration into epitaxial oxide heterostructures that have fully revealed its extraordinarily broad palette of functionalities. Here we review the first decade of research on BiFeO3 films, restricting ourselves to epitaxial structures. We discuss how thickness and epitaxial strain influence not only the unit cell parameters, but also the crystal structure, illustrated for instance by the discovery of the so-called T-like phase of BiFeO3. We then present its ferroelectric and piezoelectric properties and their evolution near morphotropic phase boundaries. Magnetic properties and their modification by thickness and strain effects, as well as optical parameters, are covered. Finally, we highlight various types of devices based on BiFeO3 in electronics, spintronics, and optics, and provide perspectives for the development of further multifunctional devices for information technology and energy harvesting.

  20. Polarization and resistivity measurements of post-crystallization changes in amorphous Fe-B-Si alloys

    International Nuclear Information System (INIS)

    Chattoraj, I.; Bhattamishra, A.K.; Mitra, A.

    1993-01-01

    The effects of grain growth and compositional changes on the electrochemical behavior and the resistivity of amorphous iron-boron-silicon (Fe 77.5 B 15 Si 7.5 ) alloys after crystallization were studied. Deterioration of the protective passive film was observed, along with increased annealing. Potentiodynamic polarization provided excellent information about microstructural and chemical changes. It was concluded that electrochemical measurements could be used in conjunction with resistivity measurements in direct studies of grain growth and chemical changes occurring in different phases of the devitrified alloy

  1. Fe-Vacancy-Induced Ferromagnetism in Tetragonal FeSe Thin Films

    International Nuclear Information System (INIS)

    Yong-Feng, Li; Gui-Bin, Liu; Li-Jie, Shi; Bang-Gui, Liu

    2009-01-01

    Motivated by recent experiments, we investigate structural, electronic, and magnetic properties of tetragonal FeSe with Fe vacancies using the state-of-the-art first-principles method. We show that Fe vacancies tend to stay in the same one of the two sublattices and thus induce ferromagnetism in the ground-state phase. Our calculated net moment is in good agreement with the experimental data available. Therefore, the ferromagnetism observed in tetragonal FeSe thin films is explained. It could be made controllable soon for spintronic applications

  2. Crystallization kinetics of amorphous aluminum-tungsten thin films

    Energy Technology Data Exchange (ETDEWEB)

    Car, T.; Radic, N. [Rugjer Boskovic Inst., Zagreb (Croatia). Div. of Mater. Sci.; Ivkov, J. [Institute of Physics, Bijenicka 46, P.O.B. 304, HR-10000 Zagreb (Croatia); Babic, E.; Tonejc, A. [Faculty of Sciences, Physics Department, Bijenicka 32, P.O.B. 162, HR-10000 Zagreb (Croatia)

    1999-01-01

    Crystallization kinetics of the amorphous Al-W thin films under non-isothermal conditions was examined by continuous in situ electrical resistance measurements in vacuum. The estimated crystallization temperature of amorphous films in the composition series of the Al{sub 82}W{sub 18} to Al{sub 62}W{sub 38} compounds ranged from 800 K to 920 K. The activation energy for the crystallization and the Avrami exponent were determined. The results indicated that the crystallization mechanism in films with higher tungsten content was a diffusion-controlled process, whereas in films with the composition similar to the stoichiometric compound (Al{sub 4}W), the interface-controlled crystallization probably occurred. (orig.) With 4 figs., 1 tab., 26 refs.

  3. Crystal structure of Fe2TiO5

    International Nuclear Information System (INIS)

    Shiojiri, M.; Sekimoto, S.; Maeda, T.; Ikeda, Y.; Iwauchi, K.

    1984-01-01

    The crystal structure of metal pseudobrookite, Fe 2 TiO 5 , is determined from high-resolution electron microscopy images observed and their computer simulated images, with the aid of electron diffraction and X-ray powder diffraction. The new structure has a monoclinic unit, containing eight molecules, with a = 2.223, b = 0.373, c = 0.980 nm, and β = 116.2 0 . The Fe, Ti, and O atoms occupy the positions (4c), +-(u, 0, w; 1/2 + u, 1/2, w), of C 2 3 (C2). The most probable parameters u and w, of Fe(1 to 4), Ti(1, 2), and O(1 to 10) are given. (author)

  4. Nanocrystalline Pd:NiFe{sub 2}O{sub 4} thin films: A selective ethanol gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Pratibha; Godbole, R.V.; Bhagwat, Sunita, E-mail: smb.agc@gmail.com

    2016-10-15

    In this work, Pd:NiFe{sub 2}O{sub 4} thin films were investigated for the detection of reducing gases. These films were fabricated using spray pyrolysis technique and characterized using X-ray diffraction (XRD) to confirm the crystal structure. The surface morphology was studied using scanning electron microscopy (SEM). Magnetization measurements were carried out using SQUID VSM, which shows ferrimagnetic behavior of the samples. These thin film sensors were tested against methanol, ethanol, hydrogen sulfide and liquid petroleum gas, where they were found to be more selective to ethanol. The fabricated thin film sensors exhibited linear response signal for all the gases with concentrations up to 5 w/o Pd. Reduction in optimum operating temperature and enhancement in response was also observed. Pd:NiFe{sub 2}O{sub 4} thin films exhibited faster response and recovery characteristic. These sensors have potential for industrial applications because of their long-term stability, low power requirement and low production cost. - Highlights: • Ethanol gas sensors based on Pd:NiFe{sub 2}O{sub 4} nanoparticle thin film were fabricated. • Pd incorporation in NiFe{sub 2}O{sub 4} matrix inhibits grain growth. • The sensors were more selective to ethanol gas. • Sensors exhibited fast response and recovery when doped with palladium. • Pd:NiFe{sub 2}O{sub 4} thin film sensor displays excellent long–term stability.

  5. Bi-substituted iron garnet films for one-dimensional magneto-photonic crystals: Synthesis and properties

    International Nuclear Information System (INIS)

    Shaposhnikov, A.N.; Karavainikov, A.V.; Prokopov, A.R.; Berzhansky, V.N.; Salyuk, O.Y.

    2012-01-01

    Graphical abstract: Faraday hysteresis loops for Bi 1.0 Y 0.5 Gd 1.5 Fe 4.2 Al 0.8 O 12 film on glass-ceramic substrate (a), Bi 2.8 Y 0.2 Fe 5 O 12 film on gallium–gadolinium garnet (b) and for glass-ceramic/SiO 2 /Bi 1.0 Y 0.5 Gd 1.5 Fe 4.2 Al 0.8 O 12 /Bi 2.8 Y 0.2 Fe 5 O 12 structure (c). Highlights: ► Bismuth-substituted iron garnet films as magneto-optical layers in magneto-photonic crystals. ► It is impossible to crystallize the films with high Bi content on amorphous substrates. ► The crystallization of the films can be achieved by their deposition on buffer layer with low bismuth content. -- Abstract: The crystallization processes in Bi 2.8 Y 0.2 Fe 5 O 12 , Bi 2.5 Gd 0.5 Fe 3.8 Al 1.2 O 12 , Bi 1.5 Gd 1.5 Fe 4.5 Al 0.5 O 12 and Bi 1.0 Y 0.5 Gd 1.5 Fe 4.2 Al 0.8 O 12 garnet films deposited by reactive ion beam sputtering on (1 1 1) gadolinium–gallium garnet substrates, optical glass-ceramic and SiO 2 films have been studied. Films were annealed at low pressure in oxygen atmosphere and in the air. The possibility of preparation of crystalline garnet films with high concentration of bismuth on the SiO 2 films using a buffer layer with low concentration of Bi has been shown. This allows to produce one-dimensional magneto-photonic crystals with high effective Faraday rotation (several tens of°/μm for the visible optical spectrum).

  6. Bi-substituted iron garnet films for one-dimensional magneto-photonic crystals: Synthesis and properties

    Energy Technology Data Exchange (ETDEWEB)

    Shaposhnikov, A.N.; Karavainikov, A.V.; Prokopov, A.R.; Berzhansky, V.N. [Taurida National V.I. Vernadsky University, Vernadsky Av., 4, 95007 Simferopol (Ukraine); Salyuk, O.Y., E-mail: olga-saliuk@yandex.ru [Institute of Magnetizm NASU and MESU, 36-B Vernadsky Blvd., 03142 Kiev (Ukraine)

    2012-06-15

    Graphical abstract: Faraday hysteresis loops for Bi{sub 1.0}Y{sub 0.5}Gd{sub 1.5}Fe{sub 4.2}Al{sub 0.8}O{sub 12} film on glass-ceramic substrate (a), Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12} film on gallium–gadolinium garnet (b) and for glass-ceramic/SiO{sub 2}/Bi{sub 1.0}Y{sub 0.5}Gd{sub 1.5}Fe{sub 4.2}Al{sub 0.8}O{sub 12}/Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12} structure (c). Highlights: ► Bismuth-substituted iron garnet films as magneto-optical layers in magneto-photonic crystals. ► It is impossible to crystallize the films with high Bi content on amorphous substrates. ► The crystallization of the films can be achieved by their deposition on buffer layer with low bismuth content. -- Abstract: The crystallization processes in Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12}, Bi{sub 2.5}Gd{sub 0.5}Fe{sub 3.8}Al{sub 1.2}O{sub 12}, Bi{sub 1.5}Gd{sub 1.5}Fe{sub 4.5}Al{sub 0.5}O{sub 12} and Bi{sub 1.0}Y{sub 0.5}Gd{sub 1.5}Fe{sub 4.2}Al{sub 0.8}O{sub 12} garnet films deposited by reactive ion beam sputtering on (1 1 1) gadolinium–gallium garnet substrates, optical glass-ceramic and SiO{sub 2} films have been studied. Films were annealed at low pressure in oxygen atmosphere and in the air. The possibility of preparation of crystalline garnet films with high concentration of bismuth on the SiO{sub 2} films using a buffer layer with low concentration of Bi has been shown. This allows to produce one-dimensional magneto-photonic crystals with high effective Faraday rotation (several tens of°/μm for the visible optical spectrum).

  7. Photoelectron diffraction of magnetic ultrathin films: Fe/Cu(001)

    Energy Technology Data Exchange (ETDEWEB)

    Tobin, J.G. (Lawrence Livermore National Lab., CA (USA)); Wagner, M.K. (Wisconsin Univ., Madison, WI (USA). Dept. of Chemistry); Guo, X.Q.; Tong, S.Y. (Wisconsin Univ., Milwaukee, WI (USA). Dept. of Physics)

    1991-01-03

    The preliminary results of an ongoing investigation of Fe/Cu(001) are presented here. Energy dependent photoelectron diffraction, including the spin-dependent variant using the multiplet split Fe3s state, is being used to investigate the nanoscale structures formed by near-monolayer deposits of Fe onto Cu(001). Core-level photoemission from the Fe3p and Fe3s states has been generated using synchrotron radiation as the tunable excitation source. Tentatively, a comparison of the experimental Fe3p cross section measurements with multiple scattering calculations indicates that the Fe is in a fourfold hollow site with a spacing of 3.6{Angstrom} between it and the atom directly beneath it, in the third layer. This is consistent with an FCC structure. The possibility of utilizing spin-dependent photoelectron diffraction to investigate magnetic ultrathin films will be demonstrated, using our preliminary spectra of the multiplet-split Fe3s os near-monolayer Fe/Cu(001). 18 refs., 10 figs.

  8. Crystallization of calcium carbonate on radiation-grafted polyethylene films

    International Nuclear Information System (INIS)

    Hou Zhengchi; Zhang Fengying; Deng Bo; Yang Haijun; Chen Shuang; Sheng Kanglong

    2006-01-01

    In biomineralization processes, nucleation and growth of inorganic crystals can be regulated by organic template molecules. This has inspired great interest in studying mimic biomineralization. In our study, growing CaCO 3 crystals on PE films functionalized through radiation-induced grafting was attempted. PE films grafted with different functional groups of different distributions and densities were used as substrates for CaCO 3 nucleation and crystal growth from Ca(HCO 3 ) 2 supersaturated solution under different environmental conditions (e.g. additives and temperature) to study the effects and mechanisms. The grafted PE films were analyzed by ATR-FTIR and AFM, and the evolution of CaCO 3 crystal formation on the grafted PE film was characterized by SEM, FTIR, and XRD. The results indicated that heterogeneous nucleation of CaCO 3 crystals was significantly facilitated by the functional groups grafted on the surface of PE films, that the morphology of CaCO 3 crystals could be controlled by distribution and density of the grafted functional groups, and that polymorphism of CaCO 3 crystal could be regulated by selection of grafting functional groups. We believe that studying the effects of chemical structures on inorganic crystallization is of great importance since radiation-induced grafting is an effective method to graft desirable functional groups onto different polymers by selected monomers, in the endeavor of developing advanced organic/inorganic composites with high performance, with a wide availability of polymers, monomers and inorganic solutions. (authors)

  9. Crystallization of the amorphous Fe80Zr12B8 alloy under controlled heating

    International Nuclear Information System (INIS)

    Huang, H.; Shao, G.; Tsakiropoulos, P.

    2008-01-01

    The devitrification process of amorphous Fe 80 Zr 12 B 8 alloy ribbons were studied under controlled thermal conditions. The major crystallization event during continuous heating with differential scanning calorimetory (DSC) is dictated by diffusion controlled growth and the associated atom mobility of the slow diffusing species Zr. The existence of prior nano-crystals formed by pre-annealing below the crystallization temperature had little effect on the major crystallization temperature. The crystallization sequence during heating was: amorphous → amorphous + α-Fe + Fe 3 Zr(B) → amorphous + α-Fe + Fe 3 Zr(B) + Fe 2 Zr. Different from previous findings in alloys of lower Zr and B contents, the peak for the crystallization of the α-Fe phase alone is missing in the DSC traces of this alloy

  10. Crystallization study of amorphous system Fe84-xWxB16 (x = 3;5)

    International Nuclear Information System (INIS)

    Novakova, A.A.; Sidorova, G.V.; Kiseleva, T.Yu.; Szasz, A.

    1992-01-01

    A complex study of the crystallization process of the amorphous system was carried out by Moessbauer spectroscopy, X-ray diffraction and DTA. Alloy samples crystallized at 600deg C contain the following phases: α-Fe, Fe 3 B and solid solution (Fe, W) 3 B. (orig.)

  11. Transparent nanostructured Fe-doped TiO2 thin films prepared by ultrasonic assisted spray pyrolysis technique

    Science.gov (United States)

    Rasoulnezhad, Hossein; Hosseinzadeh, Ghader; Ghasemian, Naser; Hosseinzadeh, Reza; Homayoun Keihan, Amir

    2018-05-01

    Nanostructured TiO2 and Fe-doped TiO2 thin films with high transparency were deposited on glass substrate through ultrasonic-assisted spray pyrolysis technique and were used in the visible light photocatalytic degradation of MB dye. The resulting thin films were characterized by scanning electron microscopy (SEM), Raman spectroscopy, photoluminescence spectroscopy, x-ray diffraction (XRD), and UV-visible absorption spectroscopy techniques. Based on Raman spectroscopy results, both of the TiO2 and Fe-doped TiO2 films have anatase crystal structure, however, because of the insertion of Fe in the structure of TiO2 some point defects and oxygen vacancies are formed in the Fe-doped TiO2 thin film. Presence of Fe in the structure of TiO2 decreases the band gap energy of TiO2 and also reduces the electron–hole recombination rate. Decreasing of the electron–hole recombination rate and band gap energy result in the enhancement of the visible light photocatalytic activity of the Fe-doped TiO2 thin film.

  12. Spin Seebeck effect in insulating epitaxial γ−Fe2O3 thin films

    Directory of Open Access Journals (Sweden)

    P. Jiménez-Cavero

    2017-02-01

    Full Text Available We report the fabrication of high crystal quality epitaxial thin films of maghemite (γ−Fe2O3, a classic ferrimagnetic insulating iron oxide. Spin Seebeck effect (SSE measurements in γ−Fe2O3/Pt bilayers as a function of sample preparation conditions and temperature yield a SSE coefficient of 0.5(1 μV/K at room temperature. Dependence on temperature allows us to estimate the magnon diffusion length in maghemite to be in the range of tens of nanometers, in good agreement with that of conducting iron oxide magnetite (Fe3O4, establishing the relevance of spin currents of magnonic origin in magnetic iron oxides.

  13. Adsorption induced modification of in-plane magnetic anisotropy in epitaxial Co and Fe/Co films on Fe(110)

    Science.gov (United States)

    Ślezak, M.; Ślezak, T.; Matlak, K.; DróŻdŻ, P.; Korecki, J.

    2018-05-01

    A study of in-plane magnetic anisotropy (MA) in epitaxial bcc Co films and Fe/Co bilayers on a Fe(110) surface is reported. Surface MA of as-deposited Co films and Fe/Co bilayers strongly depends on the Co (dCo) and Fe (dFe) thickness. Adsorption of residual gases drastically modifies in-plane MA of both Co films and Fe/Co bilayers. We present two dimensional MA maps in the (dCo, dFe) space for both as grown and adsorption-modified films. Our results indicate how to precisely engineer in-plane MA that can be controlled by dCo, dFe and is sensitive to the residual gas adsorption.

  14. AFM, XRD and HRTEM Studies of Annealed FePd Thin Films

    International Nuclear Information System (INIS)

    Perzanowski, M.; Zabila, Y.; Polit, A.; Krupinski, M.; Dobrowolska, A.; Marszalek, M.; Morgiel, J.

    2010-01-01

    Ferromagnetic FePd L1 0 ordered alloys are highly expected as forthcoming high-density recording materials, because they reveal a large perpendicular magnetocrystalline anisotropy. The value of the magnetic anisotropy of FePd alloy strongly depends on the alloy composition, degree of alloy order as well as on the crystallographic grain orientation. In particular, to obtain the perpendicular anisotropy, it is necessary to get the films with (001) texture. One of the successful methods, which allows one to obtain highly ordered alloy, is a subsequent deposition of Fe and Pd layers, followed by an annealing at high temperature. This paper presents the study of the FePd thin alloy film structure changing in the result of high temperature annealing. During the annealing in high vacuum, the measurements of electrical resistance were performed, indicating the regions of different structure evolution. Changes in the crystal structure and surface morphology induced by thermal treatment were investigated by X-ray diffraction, atomic force microscopy, as well as high resolution transmission electron microscopy and then compared with electrical resistivity measurement. The slow thermal annealing of the deposited layers leads to the formation of L1 0 ordered FePd alloy with preferred (111) grain orientation. After the annealing at the highest used temperature, the dewetting process was observed, resulting in a creation of well oriented, regular nanoparticles. (author)

  15. Thermal stability of ultrasoft Fe-Zr-N films

    NARCIS (Netherlands)

    Chechenin, NG; van Veen, A; Schut, H; Chezan, AR; Boerma, D; Vystavel, T; De Hosson, JTM

    2003-01-01

    The thermal stability of nanocrystalline ultrasoft magnetic (Fe98Zr2)(1-x)N-x films with x = 0.10-0.25 was studied using thermal desorption spectrometry, positron beam analysis and high resolution transmission electron microscopy. The results demonstrate that grain growth during the heat treatment

  16. Stripe domains in Fe-Zr-N nanocrystalline films

    NARCIS (Netherlands)

    Craus, C.B.; Craus, C.B.; Chezan, A.R.; Siekman, Martin Herman; Lodder, J.C.; Boerma, D.O.; Niesen, L.

    2002-01-01

    We report on the transition between a magnetic stripe domain structure and in-plane orientation of the spins, as a function of nitrogen content, for 500nm thick Fe-Zr-N films prepared by DC reactive sputtering on glass substrates. The saturation field decreases and the saturation magnetization

  17. Investigation of coercivity for electroplated Fe-Ni thick films

    Science.gov (United States)

    Yanai, T.; Eguchi, K.; Koda, K.; Kaji, J.; Aramaki, H.; Takashima, K.; Nakano, M.; Fukunaga, H.

    2018-05-01

    We have already reported Fe-Ni firms with good soft magnetic properties prepared by using an electroplating method. In our previous studies, we prepared the Fe-Ni films from citric-acid-based baths (CA-baths) and ammonium-chloride-based ones (AC-baths), and confirmed that the coercivity for the AC-baths was lower than that for the CA-baths. In the present study, we investigated reasons for the lower coercivity for the AC-baths to further improve the soft magnetic properties. From an observation of magnetic domains of the Fe22Ni78 films, we found that Fe22Ni78 film for AC-bath had a magnetic anisotropy in the width direction, and also found that the coercivity in the width direction was lower than the longitudinal one for the AC-bath. As an annealing for a stress relaxation in the films reduced the difference in the coercivity, we considered that the anisotropy is attributed to the magneto-elastic effect.

  18. Dense Fe cluster-assembled films by energetic cluster deposition

    International Nuclear Information System (INIS)

    Peng, D.L.; Yamada, H.; Hihara, T.; Uchida, T.; Sumiyama, K.

    2004-01-01

    High-density Fe cluster-assembled films were produced at room temperature by an energetic cluster deposition. Though cluster-assemblies are usually sooty and porous, the present Fe cluster-assembled films are lustrous and dense, revealing a soft magnetic behavior. Size-monodispersed Fe clusters with the mean cluster size d=9 nm were synthesized using a plasma-gas-condensation technique. Ionized clusters are accelerated electrically and deposited onto the substrate together with neutral clusters from the same cluster source. Packing fraction and saturation magnetic flux density increase rapidly and magnetic coercivity decreases remarkably with increasing acceleration voltage. The Fe cluster-assembled film obtained at the acceleration voltage of -20 kV has a packing fraction of 0.86±0.03, saturation magnetic flux density of 1.78±0.05 Wb/m 2 , and coercivity value smaller than 80 A/m. The resistivity at room temperature is ten times larger than that of bulk Fe metal

  19. Coercivity scaling in antidot lattices in Fe, Ni, and NiFe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gräfe, Joachim, E-mail: graefe@is.mpg.de; Schütz, Gisela; Goering, Eberhard J., E-mail: goering@is.mpg.de

    2016-12-01

    Antidot lattices can be used to artificially engineer magnetic properties in thin films, however, a conclusive model that describes the coercivity enhancement in this class of magnetic nano-structures has so far not been found. We prepared Fe, Ni, and NiFe thin films and patterned each with 21 square antidot lattices with different geometric parameters and measured their hysteretic behavior. On the basis of this extensive dataset we are able to provide a model that can describe both the coercivity scaling over a wide range of geometric lattice parameters and the influence of different materials.

  20. The annealing temperature dependences of microstructures and magnetic properties in electro-chemical deposited CoNiFe thin films

    International Nuclear Information System (INIS)

    Suharyadi, Edi; Riyanto, Agus; Abraha, Kamsul

    2016-01-01

    CoNiFe thin films with various compositions had been successfully fabricated using electro-chemical deposition method. The crystal structure of Co_6_5Ni_1_5Fe_2_0, Co_6_2Ni_1_5Fe_2_3, and Co_5_5Ni_1_5Fe_3_0 thin films was fcc, bcc-fcc mix, and bcc, respectively. The difference crystal structure results the difference in magnetic properties. The saturation magnetic flux density (Bs) of Co_6_5Ni_1_5Fe_2_0, Co_6_2Ni_1_5Fe_2_3, and Co_5_5Ni_1_5Fe_3_0 thin films was 1.89 T, 1.93 T, and 2.05 T, respectively. An optimal annealing temperature was determined for controlling the microstructure and magnetic properties of CoNiFe thin films. Depending on annealing temperature, the ratio of bcc and fcc structure varied without changing the film composition. By annealing at temperature of T ≥ 350°C, the intensity ratio of X-ray diffraction peaks for bcc(110) to fcc(111) increased. The increase of phase ratio of bcc(110) to fcc(111) caused the increase of Bs, from 1.89 T to 1.95 T. Coercivity (Hc) also increased after annealing, from 2.6 Oe to 18.6 Oe for fcc phase thin films, from 2.0 Oe to 12.0 Oe for fcc-bcc mix phase thin films, and 7.8 Oe to 8 Oe for bcc phase thin films. The changing crystal structures during annealing process indicated that the thermal treatment at high temperature cause the changing crystallinity and atomic displacement. The TEM bright-field images with corresponding selected-area electron diffraction (SAED) patterns showed that there are strongly effects of thermal annealing on the size of fcc and bcc phase crystalline grain as described by size of individual spot and discontinuous rings. The size of crystalline grains increased by thermal annealing. The evolution of bcc and fcc structures of CoNiFe during annealing is though to be responsible for the change of magnetic properties.

  1. Surface characterization of amorphous and crystallized Fe 80B 20

    Science.gov (United States)

    Huntley, D. R.; Overbury, S. H.; Zehner, D. M.; Budai, J. D.; Brower, W. E.

    1986-11-01

    Recent studies of catalysis by amorphous metals have prompted an interest in their surface properties. We have utilized Auger electron spectroscopy, X-ray photoelectron spectroscopy and low energy alkali ion scattering to study the surface composition, electronic properties and topography of amorphous and crystallized Fe 80B 20 ribbons. The majorresults are that the surface stoichiometry is approximately that of the bulk, unaltered by segregation. Bulk crystallization results in the diffusion of impurities to the surface, but does not change the Fe/B ratio. A small shift in the B1s core level binding energy was observed on crystalline, annealed surfaces relative to amorphous or sputtered surfaces, but no shifts were observed in the iron core level energies. A weak feature due to the B2p levels was observed in the valence band spectra from sputtered surfaces. The surfaces exhibit atomic scale roughness which is not altered by bulk crystallization. Finally, there were no observable differences in the structure, composition or electronic properties between the two sides of the ribbons.

  2. Magnetoresistances in Ni80Fe20-ITO granular film

    International Nuclear Information System (INIS)

    Gao Chunhong; Chen Ke; Yang Yanxia; Xiong Yuanqiang; Chen Peng

    2012-01-01

    Highlights: ► Magnetoresistance (MR) in Ni 80 Fe 20 -ITO granular film are investigated. ► MR is positive at high temperature, and is negative at low temperature. ► MR results from the competition among three mechanisms. - Abstract: The magnetic properties, electrical properties and magnetoresistance are investigated in Ni 80 Fe 20 -ITO granular film with various volume fractions V NF of Ni 80 Fe 20 . The room temperature magnetization hysteresis of sample with V NF = 25% shows superparamagnetic behavior. Current-voltage curve of sample with V NF = 25% at 175 K shows typical tunneling-type behavior. The magnetoresistances of samples with low V NF are positive at high temperature, and are negative at low temperature. The temperature-dependent magnetoresistances result from the competition among ordinary magnetoresistances, the granular-typed tunneling magnetoresistance and the spin-mixing induced magnetoresistances.

  3. Rapid thermal annealing of FePt and FePt/Cu thin films

    Energy Technology Data Exchange (ETDEWEB)

    Brombacher, Christoph

    2011-01-10

    Chemically ordered FePt is one of the most promising materials to reach the ultimate limitations in storage density of future magnetic recording devices due to its high uniaxial magnetocrystalline anisotropy and a corrosion resistance superior to rare-earth based magnets. In this study, FePt and FePt/Cu bilayers have been sputter deposited at room temperature onto thermally oxidized silicon wafers, glass substrates and self-assembled arrays of spherical SiO{sub 2} particles with diameters down to 10 nm. Millisecond flash lamp annealing, as well as conventional rapid thermal annealing was employed to induce the phase transformation from the chemically disordered A1 phase into the chemically ordered L1{sub 0} phase. The influence of the annealing temperature, annealing time and the film thickness on the ordering transformation and (001) texture evolution of FePt films with near equiatomic composition was studied. Whereas flash lamp annealed FePt films exhibit a polycrystalline morphology with high chemical L1{sub 0} order, rapid thermal annealing can lead to the formation of chemically ordered FePt films with (001) texture on amorphous SiO{sub 2}/Si substrates. The resultant high perpendicular magnetic anisotropy and large coercivities up to 40 kOe are demonstrated. Simultaneously to the ordering transformation, rapid thermal annealing to temperatures exceeding 600 C leads to a break up of the continuous FePt film into separated islands. This dewetting behavior was utilized to create regular arrays of FePt nanostructures on SiO{sub 2} particle templates with periods down to 50 nm. The addition of Cu improves the (001) texture formation and chemical ordering for annealing temperatures T{sub a} {<=}600 C. In addition, the magnetic anisotropy and the coercivity of the ternary FePtCu alloy can be effectively tailored by adjusting the Cu content. The prospects of FePtCu based exchange spring media, as well as the magnetic properties of FePtCu nanostructures fabricated

  4. Effects of deposition temperature and in-situ annealing time on structure and magnetic properties of (001) orientation FePt films

    International Nuclear Information System (INIS)

    Yu, Yongsheng; George, T.A.; Li, Haibo; Sun, Daqian; Ren, Zhenan; Sellmyer, D.J.

    2013-01-01

    FePt films were prepared on (100) oriented single crystal MgO substrates at high temperature ranging from 620 until 800 °C and in-situ annealed for different times ranging from 0 to 60 min to obtain ordered FePt films. The structural analysis indicates that FePt films grow epitaxially on MgO (100) substrates. Both increasing deposition temperature and in-situ annealing time enhance the (001) texture and ordering of FePt films. The magnetic analysis shows that these L1 0 FePt films have perpendicular anisotropy and the easy magnetization c-axis is perpendicular to the film plane. Magnetization reversal is controlled by a rotational mechanism. The hard magnetic properties of the films are improved with increasing deposition temperature or in-situ annealing time. - Highlights: ► The paper reports the texture and magnetic evolution of FePt films deposited on MgO substrates. ► Increasing deposition temperature or annealing time enhanced the texture and ordering. ► The magnetic analysis shows L1 0 FePt films have perpendicular anisotropy.

  5. Photoconductivity in BiFeO3 thin films

    Science.gov (United States)

    Basu, S. R.; Martin, L. W.; Chu, Y. H.; Gajek, M.; Ramesh, R.; Rai, R. C.; Xu, X.; Musfeldt, J. L.

    2008-03-01

    The optical properties of epitaxial BiFeO3 thin films have been characterized in the visible range. Variable temperature spectra show an absorption onset near 2.17eV, a direct gap (2.667±0.005eV at 300K), and charge transfer excitations at higher energy. Additionally, we report photoconductivity in BiFeO3 films under illumination from a 100mW /cm2 white light source. A direct correlation is observed between the magnitude of the photoconductivity and postgrowth cooling pressure. Dark conductivities increased by an order of magnitude when comparing films cooled in 760 and 0.1Torr. Large increases in photoconductivity are observed in light.

  6. Magnetoresistance anomaly in DyFeCo thin films

    International Nuclear Information System (INIS)

    Wu, J. C.; Wu, C. S.; Wu, Te-ho; Chen, Bing-Mau; Shieh, Han-Ping D.

    2001-01-01

    Microstructured rare-earth - transition-metal DyFeCo films have been investigated using magnetoresistance and extraordinary Hall-effect measurements. The Hall loops reveal variation of coercive fields depending on the linewidth and the composition of the films. The magnetoresistance curves, with changes up to as high as 1.3%, show positive/negative magnetoresistance peaks centered on the coercive fields depending on the linewidth of the films only. The variation of the coercivity can be attributed to the magnetic moment canting between the Dy and FeCo subcomponents and the existence of the diverged magnetization on the edges, and the anomalous magnetoresistance peaks observed are discussed with the existing theories. [copyright] 2001 American Institute of Physics

  7. Surface and bulk crystallization of amorphous solid water films: Confirmation of “top-down” crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Chunqing; Smith, R. Scott; Kay, Bruce D.

    2016-10-01

    The crystallization kinetics of nanoscale amorphous solid water (ASW) films are investigated using temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS). TPD measurements are used to probe surface crystallization and RAIRS measurements are used to probe bulk crystallization. Isothermal TPD results show that surface crystallization is independent of the film thickness (from 100 to 1000 ML). Conversely, the RAIRS measurements show that the bulk crystallization time increases linearly with increasing film thickness. These results suggest that nucleation and crystallization begin at the ASW/vacuum interface and then the crystallization growth front propagates linearly into the bulk. This mechanism was confirmed by selective placement of an isotopic layer (5% D2O in H2O) at various positions in an ASW (H2O) film. In this case, the closer the isotopic layer was to the vacuum interface, the earlier the isotopic layer crystallized. These experiments provide direct evidence to confirm that ASW crystallization in vacuum proceeds by a “top-down” crystallization mechanism.

  8. Tuning high frequency magnetic properties and damping of FeGa, FeGaN and FeGaB thin films

    Directory of Open Access Journals (Sweden)

    Derang Cao

    2017-11-01

    Full Text Available A series of FeGa, FeGaN and FeGaB films with varied oblique angles were deposited by sputtering method on silicon substrates, respectively. The microstructure, soft magnetism, microwave properties, and damping factor for the films were investigated. The FeGa films showed a poor high frequency magnetic property due to the large stress itself. The grain size of FeGa films was reduced by the additional N element, while the structure of FeGa films was changed from the polycrystalline to amorphous phase by the involved B element. As a result, N content can effectively improve the magnetic softness of FeGa film, but their high frequency magnetic properties were still poor both when the N2/Ar flow rate ratio is 2% and 5% during the deposition. The additional B content significantly led to the excellent magnetic softness and the self-biased ferromagnetic resonance frequency of 1.83 GHz for FeGaB film. The dampings of FeGa films were adjusted by the additional N and B contents from 0.218 to 0.139 and 0.023, respectively. The combination of these properties for FeGa films are helpful for the development of magnetostrictive microwave devices.

  9. Study of memory effects in polymer dispersed liquid crystal films

    International Nuclear Information System (INIS)

    Han, Jinwoo

    2006-01-01

    In this work, we have studied the memory effects in polymer dispersed liquid crystal films. We found that optical responses, such as the memory effects, of the films depended strongly on the morphology. For example, memory effects were observed for films with polymer ball morphologies; however, only weak hysteresis effects were observed for films with droplet morphologies. In particular, a stronger memory effect was observed for films with more complicated polymer ball structures. Coincidentally, T TE , the temperature at which the memory state is thermally erased, was generally higher for the films exhibiting a stronger memory effect. In addition, studies of the temporal evolution of the films show that the memory effects become stronger after films have been kept on the shelf for a period of time. This change is likely to be associated with a modification of surface anchoring properties at the LC-polymer interface.

  10. Electrochemical vs X-ray Spectroscopic Measurements of NiFe(CN)6 Crystals

    Science.gov (United States)

    Peecher, Benjamin; Hampton, Jennifer

    Pseudocapacitive materials like hexacyanoferrate have greater energy storage capabilities than standard capacitors while maintaining an ability to charge and discharge quickly. We modify the surface of an electrodeposited Ni thin film with a layer of hexacyanoferrate. Charging and discharging these modified films using cyclic voltammetry (CV) allows us to measure the electrochemically active Fe in the film. To determine how closely this resembles the full amount of Fe in the film, we measure the films' composition using particle-induced x-ray emission (PIXE). We also vary the amount of Ni deposited, both to compare the electrolysis value of charge deposited to the PIXE measurement of Ni in the film, and also to measure how varying the thickness of the Ni surface affects the presence of Fe in the film. Comparisons of the CV and PIXE measurements show agreement in Ni levels but disagreement in Fe levels. PIXE measurements of Fe in the film have positive correlation with Ni in the film. This correlation between PIXE measurements of Ni and Fe suggests that PIXE provides a reliable measure of Fe in the film. This implies that a variable proportion of total Fe in a given film is electrochemically active. This research was made possible by the Hope College Department of Physics Frissel Research Fund and the National Science Foundation under Grants RUI-DMR-1104725, MRI-CHE-0959282, and MRI/RUI-PHY-0319523.

  11. Electrodeposited Fe-Co films prepared from a citric-acid-based plating bath

    OpenAIRE

    Yanai, Takeshi; Uto, H.; Shimokawa, Takaya; Nakano, Masaki; Fukunaga, Hirotoshi; Suzuki, K.

    2013-01-01

    Electrodeposited Fe-Co films are commonly prepared in a boric-acid-based bath. In this research, we applied citric acid instead of boric acid for the plating of Fe-Co films because boron in the waste bath is restricted by environmental-protection regulations in Japan. We evaluated the effect of citric acid on the magnetic and structural properties of the films. The saturation magnetization of the Fe-Co films slightly increased while the Fe content in the Fe-Co films decreased with increasing ...

  12. Peeling off effects in vertically aligned Fe3C filled carbon nanotubes films grown by pyrolysis of ferrocene

    Science.gov (United States)

    Boi, Filippo S.; Medranda, Daniel; Ivaturi, Sameera; Wang, Jiayu; Guo, Jian; Lan, Mu; Wen, Jiqiu; Wang, Shanling; He, Yi; Mountjoy, Gavin; Willis, Maureen A. C.; Xiang, Gang

    2017-06-01

    We report the observation of an unusual self-peeling effect which allows the synthesis of free standing vertically aligned carbon nanotube films filled with large quantities of Fe3C and small quantities of γ-Fe crystals. We demonstrate that this effect depends on the interplay of three main factors: (1) the physical interactions between the chosen substrate surface and grown carbon nanotubes (CNTs), which is fixed by the composition of the used substrate (111 SiO2/Si or quartz), (2) the CNT-CNT Van der Waals interactions, and (3) the differential thermal contraction between the grown CNT film and the used substrate, which is fixed by the cooling rate differences between the grown film and the used quartz or Si/SiO2 substrates. The width and stability of these films are then further increased to cm-scale by addition of small quantities of toluene to the ferrocene precursor.

  13. Preparation of c-axis perpendicularly oriented ultra-thin L10-FePt films on MgO and VN underlayers

    Science.gov (United States)

    Futamoto, Masaaki; Shimizu, Tomoki; Ohtake, Mitsuru

    2018-05-01

    Ultra-thin L10-FePt films of 2 nm average thickness are prepared on (001) oriented MgO and VN underlayers epitaxially grown on base substrate of SrTiO3(001) single crystal. Detailed cross-sectional structures are observed by high-resolution transmission electron microscopy. Continuous L10-FePt(001) thin films with very flat surface are prepared on VN(001) underlayer whereas the films prepared on MgO(001) underlayer consist of isolated L10-FePt(001) crystal islands. Presence of misfit dislocation and lattice bending in L10-FePt material is reducing the effective lattice mismatch with respect to the underlayer to be less than 0.5 %. Formation of very flat and continuous FePt layer on VN underlayer is due to the large surface energy of VN material where de-wetting of FePt material at high temperature annealing process is suppressed under a force balance between the surface and interface energies of FePt and VN materials. An employment of underlayer or substrate material with the lattice constant and the surface energy larger than those of L10-FePt is important for the preparation of very thin FePt epitaxial thin continuous film with the c-axis controlled to be perpendicular to the substrate surface.

  14. All-optical measurement of interlayer exchange coupling in Fe/Pt/FePt thin films

    Science.gov (United States)

    Berk, C.; Ganss, F.; Jaris, M.; Albrecht, M.; Schmidt, H.

    2018-01-01

    Time Resolved Magneto Optic Kerr Effect spectroscopy was used to all-optically study the dynamics in exchange coupled Fe(10 nm)/Pt(x = 0-5 nm)/FePt (10 nm) thin films. As the Pt spacer decreases, the effective magnetization of the layers is seen to evolve towards the strong coupling limit where the two films can be described by a single effective magnetization. The coupling begins at x = 1.5 nm and reaches a maximum exchange coupling constant of 2.89 erg/cm2 at x = 0 nm. The films are ferromagnetically coupled at all Pt thicknesses in the exchange coupled regime (x ≤ 1.5 nm). A procedure for extracting the interlayer exchange constant by measuring the magnetic precession frequencies at multiple applied fields and angles is outlined. The dynamics are well reproduced using micromagnetic simulations.

  15. Optical and structural properties of FeSe2 thin films obtained by selenization of sprayed amorphous iron oxide films

    International Nuclear Information System (INIS)

    Ouertani, B.; Ouerfelli, J.; Saadoun, M.; Zribi, M.; Rabha, M.Ben; Bessais, B.; Ezzaouia, H.

    2006-01-01

    We report in this work the optical and structural properties of iron diselenide films (FeSe 2 ) obtained by selenization under vacuum of amorphous iron oxide films predeposited by spray pyrolysis. The structure of the FeSe 2 films was investigated by scanning electron microscopy (SEM), microprobe analyses, atomic force microscopy (AFM) and X-ray diffraction (XRD). XRD and micro-probe analyses showed that FeSe 2 as well as FeSe 2-x phases begin to appear at a selenization temperature of 500 deg. C. As the selenization temperature rises, the iron diselenide films become more stoichiometric with a dominance of the FeSe 2 phase. At 550 deg. C, a single FeSe 2 phase having good crystallinity was obtained. At 600 deg. C, two phases were detected: the major one corresponds to Fe 3 O 4 , and the minor one to FeSe 2 . SEM surface views show that FeSe 2 films have granular structure with small spherical crystallites. However, layered and clustered FeSe 2 films were found, respectively, at 550 deg. C and 600 deg. C. Absorption measurements show that iron diselenide films have a direct and an indirect gaps of about 1.03 eV and 0.3 eV, which were suggested to be due to the stoichiometric FeSe 2 phase and to a Fe-rich non-stoichiometric phase, respectively

  16. Magnetic structure of Tb-Fe films with an artificially layered structure

    International Nuclear Information System (INIS)

    Yamauchi, K.; Habu, K.; Sato, N.

    1988-01-01

    The magnetic structure of Tb-Fe films with an artificially layered structure has been investigated by measuring the temperature dependence of the magnetization of the films. Ferrimagnetic coupling between Tb and Fe through the interface was explicitly observed up to about 9-A Tb and 10-A Fe layers. Films with thinner Tb and Fe layers than these thicknesses are composed of only ferrimagnetically coupled Tb-Fe regions. Films with thicker layers of Tb and Fe are composed of ferrimagnetically coupled Tb-Fe, ferromagnetic Fe, ferromagnetic Tb, and/or magnetically compensated Tb regions. The Tb-Fe films exhibit various temperature dependencies of the magnetization corresponding to these magnetic structures

  17. Mössbauer and Kerr microscopy investigation of crystallization in FeCoB ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, V. Raghavendra, E-mail: varimalla@yahoo.com, E-mail: vrreddy@csr.res.in; Hussain, Zaineb; Babu, Hari [UGC DAE Consortium for Scientific Research, University Campus, Kandhwa Road, Indore-452001 India (India); Shrivastava, Namrata [School of Physics, DAVV, Khandwa Road, Indore – 452001 India (India); Gupta, Ajay [Amity Centre for Spintronic Materials, Amity University, Noida 201303.India (India)

    2016-05-23

    The present work reports the crystallization study of amorphous FeCoB ribbons using x-ray diffraction, {sup 57}Fe Mössbauer spectroscopy in transmission mode and magneto-optical Kerr (MOKE) microscopy. Annealing at 673 K is found to result in crystallization. From the Mossbauer measurements it is observed that the Fe magnetic moments are in the plane of sample for as-cast ribbon; α-FeCo, (Fe{sub 0.5}Co{sub 0.5}){sub 2}B and Fe{sub 2}B phases are formed after crystallization. MOKE microscopy revealed that wide 180° domain walls & narrow fingerprint domains are observed before crystallization and fine domains are observed after crystallization. The results are explained in terms of the presence of internal stresses and their annealing with thermal heat treatment.

  18. Structural, magnetic and optical properties of Y bFe2O4 films deposited by spin coating

    Directory of Open Access Journals (Sweden)

    Tatsuo Fujii

    2016-08-01

    Full Text Available Rare-earth iron oxides (RFe2O4 have attracting attention as new electronic device materials because of their numerous functionalities, such as electronic ferroelectricity, ferrimagnetism, and high infrared absorption. In this paper, nearly monophasic Y bFe2O4 films were prepared on α-Al2O3(001 substrates by the spin coating method using an aqueous-based Y bFe2O4 solution. The solution was composed of a stoichiometric ratio of Y b(CH3COO3 and Fe(NO33 with excess chelating agents. After heat treatment above 800 °C, well-crystallized and highly (001-oriented Y bFe2O4 started to epitaxially form on the substrate under controlled oxygen partial pressure with H2/CO2 gas mixtures. X-ray pole figure analysis confirmed the following epitaxial relationship: Y bFe2O4[100](001//α-Al2O3[100](001. Moreover formation of an Fe3O4 interracial layer between Y bFe2O4 and α-Al2O3 was detected by high-resolution transmission electron microscopy. Presence of the Fe3O4 interracial layer seemed to release the lattice misfit with the substrate. The Fe2+/Fe3+ ratio in the obtained Y bFe2O4 films was nearly stoichiometric and the indirect bandgap assigned to Fe2+ → Fe3+ charge transfer excitation was found to be ∼0.4 eV by optical spectroscopy. A clear magnetic transition from the paramagnetic state to the ferrimagnetic state occurred at ∼230 K.

  19. Magneto-thermoelectric effects in NiFe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Schmid, Maximilian

    2015-11-01

    In this thesis magneto-thermoelectric effects are investigated in a systematic way to separate the transverse spin Seebeck effect from other parasitic effects like the anomalous Nernst effect. In contrast to the first studies found in the literature, in NiFe thin films a contribution of the transverse spin Seebeck effect can be excluded. This surprising outcome was crosschecked in a variety of different sample layouts and collaborations with other universities to ensure the validity of these results. In general, this thesis solves a long time discussion about the existence of the transverse spin Seebeck effect in NiFe films and supports the importance of control measurements for the scientific community. Even if such ''negative'' results may not be the award winning ones, new discoveries should be treated with constructive criticism and be checked carefully by the scientific community.

  20. Magnetic domains in epitaxial (100) Fe thin films

    International Nuclear Information System (INIS)

    Florczak, J.M.; Dahlberg, E.D.; Ryan, P.J.; White, R.M.; Kuznia, J.N.; Wowchak, A.M.; Cohen, P.I.

    1989-01-01

    This paper discusses the investigation of the domain patterns of thin Fe films (10 nm) grown on In x Ga 1 - x As (0.09< x<0.25)/GaAs substrates by use of Kerr microscopy. For this investigation, two types of InGaAs buffer layers were prepared. One consisted of a single, thick InGaAs layer and the second composed of an InGaAs strained layer superlattice. Both were grown on (100) GaAs substrates. The study showed that many of the domain walls were approximately parallel to the easy axis of Fe for those films grown on the low x alloy, e.g. x = 0.1, InGaAs buffer layers

  1. Crystallization kinetics of a-Se, part 4: thin films

    Science.gov (United States)

    Svoboda, Roman; Gutwirth, Jan; Málek, Jiří

    2014-09-01

    Differential scanning calorimetry was used to study the crystallization behaviour of selenium thin films in dependence on film thickness and deposition rate. In the current work, which is the fourth in a sequence of articles dealing with crystallization kinetics of a-Se, the non-isothermal crystallization kinetics was described in terms of the Johnson-Mehl-Avrami nucleation-growth model. Two-dimensional crystallite growth, consistent with the idea of sterically restricted crystallization in a thin layer, was confirmed for all data. It was found that neither the film thickness (tested within the 100-2350 nm range) nor the deposition rate appears to have any significant influence on the crystallization kinetics. However, the higher amount of intrinsic defects possibly produced by a higher deposition rate seems to accelerate the crystallization, shifting it towards lower temperatures. Very good correlation between the results obtained for thin films and those for fine powders was found. Based on the obtained results, interpretations of relevant literature data were made.

  2. Magnetic viscosity study in FePt/C granular films

    International Nuclear Information System (INIS)

    Huang, Y.; Butler, W.; Zhang, Y.; Hadjipanayis, G.C.; Weller, D.

    2004-01-01

    The magnetic viscosity of FePt/C granular thin films was studied in the temperature range from 2 to 300 K in order to examine the thermal stability of the nanoparticles. The magnetic viscosity coefficient (S max ) was found to decrease with temperature because of decreased thermal activation. At low temperatures, S max showed an almost linear dependence on temperature. However, S max does not extrapolate to zero but seems to have a finite value at cryogenic temperatures

  3. Anisotropies in sputtered FeCoV films and FeCoV/Ti:N multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Clemens, D.; Vananti, A.; Terrier, C.; Boeni, P.; Schnyder, B.; Tixier, S.; Horisberger, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-09-01

    SQUID and MOKE magnetometry as well as mechanical and X-ray stress analysis have been used in order to prove the magnetostrictive nature of the anisotropy in Fe{sub 0.50}Co{sub 0.48}V{sub 0.02} films and Fe{sub 0.50}Co{sub 0.48}V{sub 0.02} /Ti:N multilayers. The investigation stresses on the dependence on the sputter gas pressure and on the thickness of the deposited layer. (author) 1 fig., 6 refs.

  4. Electrochemical and surface characterisation of carbon-film-coated piezoelectric quartz crystals

    International Nuclear Information System (INIS)

    Pinto, Edilson M.; Gouveia-Caridade, Carla; Soares, David M.; Brett, Christopher M.A.

    2009-01-01

    The electrochemical properties of carbon films, of thickness between 200 and 500 nm, sputter-coated on gold- and platinum-coated 6 MHz piezoelectric quartz crystal oscillators, as new electrode materials have been investigated. Comparative studies under the same experimental conditions were performed on bulk electrodes. Cyclic voltammetry was carried out in 0.1 M KCl electrolyte solution, and kinetic parameters of the model redox systems Fe(CN) 6 3-/4- and [Ru(NH 3 ) 6 ] 3+/2+ as well as the electroactive area of the electrodes were obtained. Atomic force microscopy was used in order to examine the surface morphology of the films, and the properties of the carbon films and the electrode-solution interface were studied by electrochemical impedance spectroscopy. The results obtained demonstrate the feasibility of the preparation and development of nanometer thick carbon film modified quartz crystals. Such modified crystals should open up new opportunities for the investigation of electrode processes at carbon electrodes and for the application of electrochemical sensing associated with the EQCM.

  5. Applications of thin-film sandwich crystallization platforms

    Energy Technology Data Exchange (ETDEWEB)

    Axford, Danny, E-mail: danny.axford@diamond.ac.uk; Aller, Pierre; Sanchez-Weatherby, Juan; Sandy, James [Diamond Light Source, Harwell Oxford, Didcot OX11 0DE (United Kingdom)

    2016-03-24

    Crystallization via sandwiches of thin polymer films is presented and discussed. Examples are shown of protein crystallization in, and data collection from, solutions sandwiched between thin polymer films using vapour-diffusion and batch methods. The crystallization platform is optimal for both visualization and in situ data collection, with the need for traditional harvesting being eliminated. In wells constructed from the thinnest plastic and with a minimum of aqueous liquid, flash-cooling to 100 K is possible without significant ice formation and without any degradation in crystal quality. The approach is simple; it utilizes low-cost consumables but yields high-quality data with minimal sample intervention and, with the very low levels of background X-ray scatter that are observed, is optimal for microcrystals.

  6. Epitaxial growth of bcc-FexCo100-x thin films on MgO(1 1 0) single-crystal substrates

    International Nuclear Information System (INIS)

    Ohtake, Mitsuru; Nishiyama, Tsutomu; Shikada, Kouhei; Kirino, Fumiyoshi; Futamoto, Masaaki

    2010-01-01

    Fe x Co 100-x (x=100, 65, 50 at%) epitaxial thin films were prepared on MgO(1 1 0) single-crystal substrates heated at 300 deg. C by ultra-high vacuum molecular beam epitaxy. The film structure and the growth mechanism are discussed. FeCo(2 1 1) films with bcc structure grow epitaxially on MgO(1 1 0) substrates with two types of variants whose orientations are rotated around the film normal by 180 deg. each other for all compositions. Fe x Co 100-x film growth follows the Volmer Weber mode. X-ray diffraction analysis indicates the out-of-plane and the in-plane lattice spacings are in agreement with the values of respective bulk Fe x Co 100-x crystals with very small errors less than ±0.4%, suggesting the strains in the films are very small. High-resolution cross-sectional transmission electron microscopy shows that periodical misfit dislocations are preferentially introduced in the film at the Fe 50 Co 50 /MgO interface along the MgO[1 1-bar 0] direction. The presence of such periodical dislocations decreases the large lattice mismatch of about -17% existing at the FeCo/MgO interface along the MgO[1 1-bar 0] direction.

  7. Asymmetrically shaped hysteresis loop in exchange-biased FeNi/FeMn film

    International Nuclear Information System (INIS)

    Gnatchenko, S.L.; Merenkov, D.N.; Bludov, A.N.; Pishko, V.V.; Shakhayeva, Yu.A.; Baran, M.; Szymczak, R.; Novosad, V.A.

    2006-01-01

    The magnetization reversal of the bilayer polycrystalline FeNi(50 A)/FeMn(50 A) film sputtered in a magnetic field has been studied by magnetic and magneto-optical techniques. The external magnetic fields were applied along the easy or hard magnetization axis of the ferromagnetic permalloy layer. The asymmetry of hysteresis loop has been found. Appreciable asymmetry and the exchange bias were observed only in the field applied along the easy axis. The specific features of magnetization reversal were explained within the phenomenological model that involves high-order exchange anisotropy and misalignment of the easy axes of the antiferromagnetic and ferromagnetic layers. It has been shown that the film can exist in one of three equilibrium magnetic states in the field applied along the easy axis. The transitions between these states occur as first-order phase transitions. The observed hysteresis loop asymmetry is related to the existence of the metastable state

  8. Measurements on very small single crystals of NdFeB using a vibrating reed magnetometer

    International Nuclear Information System (INIS)

    Richter, H.J.; Hempel, K.A.; Verhoef, R.

    1988-01-01

    Nd 2 Fe 14 B single crystals with magnetic moments ranging from 1.6 x 10 -8 Acm 2 to 9.5 x 10 -7 Acm 2 are measured using the ultra high sensitivity vibrating reed magnetometer. The hysteresis loops are compared to those of BaFe 12 O 19 single crystals. It turns out that the magnetization reversal of the Nd 2 Fe 14 B samples is similar to that of BaFe 12 O 19 single crystals if the ferrite samples are considerably bigger in size. This does not hold for bigger Nd 2 Fe 14 B particles where stronger domain wall pinning is observed. For very small grains of Nd 2 Fe 14 B there is still evidence of domain wall processes while for BaFe 12 O 19 grains of the same size true single domain behaviour can be observed

  9. L1{sub 0}-FePt films fabricated by wet-chemical route

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Xiaoliang; Xiao, Wen; Bao, Nina; Li, Weimin; Chichvarina, Olga, E-mail: A0077107@nus.edu.sg; Ding, Jun, E-mail: msedingj@nus.edu.sg

    2015-08-31

    In this work, we have developed a method to fabricate FePt films by a combination of chemical deposition and post-annealing. Pt-doped Fe films were deposited on Pt(100 nm)/Ti(50 nm)/SiO{sub 2}/Si substrate using thermal deposition and the as-deposited films were subsequently annealed from 300 °C to 800 °C under 5% H{sub 2}/95% N{sub 2}. FePt films were achieved through diffusion and rearrangement of Fe and Pt atoms in post-annealing process. From X-ray diffraction results, the face-centered cubic (fcc) FePt phase appeared at 300 °C and the transformation from fcc to L1{sub 0} phase started at 400 °C. The L1{sub 0}-FePt film possessed an out-of-plane anisotropy and a coercivity of 729 kA/m after annealing at 600 °C. A further increase in annealing temperature led to lower value of coercivity, probably because of grain growth. In addition, the thickness of Pt-doped Fe films could be controlled from 150 nm to 700 nm by adjusting the amount of surfactant used. Our superconducting quantum interference device analysis showed that Pt dopant could significantly improve the chemical stability of Fe films in air. - Highlights: • We fabricated FePt film by a combination of chemical deposition and post-annealing. • L1{sub 0} FePt film was formed by Fe/Pt diffusion in annealing of Pt-doped Fe film. • L1{sub 0}-phase FePt with high coercivity and small out-of-plane anisotropy • Relatively small amount of Pt dopant can enhance chemical stability greatly. • We studied structure and magnetic property of as-deposited and annealed FePt film.

  10. High magnetic field properties of Fe-pnictide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kurth, Fritz

    2015-11-20

    The recent discovery of high-temperature superconductivity in Fe-based materials triggered worldwide efforts to investigate their fundamental properties. Despite a lot of similarities to cuprates and MgB{sub 2}, important differences like near isotropic behaviour in contrast to cuprates and the peculiar pairing symmetry of the order parameter (OP) have been reported. The OP symmetry of Fe-based superconductors (FBS) was theoretically predicted to be of so-called s± state prior to various experimental works. Still, most of the experimental results favour the s± scenario; however, definitive evidence has not yet been reported. Although no clear understanding of the superconducting mechanisms yet exists, potential applications such as high-field magnets and Josephson devices have been explored. Indeed, a lot of reports about FBS tapes, wires, and even SQUIDs have been published to this date. In this thesis, the feasibility of high-field magnet applications of FBS is addressed by studying their transport properties, involving doped BaFe{sub 2}As{sub 2} (Ba-122) and LnFeAs(O,F) [Ln=Sm and Nd]. Particularly, it is important to study physical properties in a sample form (i.e. thin films) that is close to the conditions found in applications. However, the realisation of epitaxial FBS thin films is not an easy undertaking. Recent success in growing epitaxial FBS thin films opens a new avenue to delve into transport critical current measurements. The information obtained through this research will be useful for exploring high-field magnet applications. This thesis consists of 7 chapters: Chapter 1 describes the motivation of this study, the basic background of superconductivity, and a brief summary of the thin film growth of FBS. Chapter 2 describes experimental methods employed in this study. Chapter 3 reports on the fabrication of Co-doped Ba-122 thin films on various substrates. Particular emphasis lies on the discovery of fluoride substrates to be beneficial for

  11. Oxygen vacancy induced magnetization switching in Fe{sub 3}O{sub 4} epitaxial ultrathin films on GaAs(100)

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhaocong, E-mail: zhaocong.huang@gmail.com [Department of Physics, Southeast University, Nanjing 211189 (China); Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York YO10 5DD (United Kingdom); School of Electronic Science and Engineering, Southeast University, Nanjing 210096 (China); Chen, Qian; Zhai, Ya, E-mail: yazhai@seu.edu.cn, E-mail: jlwang@seu.edu.cn; Wang, Jinlan, E-mail: yazhai@seu.edu.cn, E-mail: jlwang@seu.edu.cn [Department of Physics, Southeast University, Nanjing 211189 (China); Xu, Yongbing [Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York YO10 5DD (United Kingdom); Wang, Baoping [School of Electronic Science and Engineering, Southeast University, Nanjing 210096 (China)

    2015-05-04

    The magnetic and transport properties of half metallic Fe{sub 3}O{sub 4}, which are sensitive to the stoichiometry, are the key issue for applications in spintronics. An anomalous enlargement of the saturation magnetic moment is found in a relatively thick sample of epitaxial Fe{sub 3}O{sub 4} film by post-growth oxidation method. The investigation of the thickness dependence of magnetic moment suggests that the enhanced magnetism moment may come from the existence of oxygen vacancies. First-principles calculations reveal that with oxygen vacancies in Fe{sub 3}O{sub 4} crystal the spin of Fe ions in the tetrahedron site near the vacancy is much easier to switch parallel to the Fe ions in the octahedron site by temperature disturbance, supported by the temperature dependence of magnetic moment of Fe{sub 3}O{sub 4} films in experiment.

  12. Structural and optical properties of cobalt doped multiferroics BiFeO3 nanostructure thin films

    Science.gov (United States)

    Prasannakumara, R.; Naik, K. Gopalakrishna

    2018-05-01

    Bismuth ferrite (BiFeO3) and Cobalt doped BiFeO3 (BiFe1-XCoXO3) nanostructure thin films were deposited on glass substrates by the sol-gel spin coating method. The X-ray diffraction patterns (XRD) of the grown BiFeO3 and BiFe1-XCoXO3 nanostructure thin films showed distorted rhombohedral structure. The shifting of peaks to higher angles was observed in cobalt doped BiFeO3. The surface morphology of the BiFeO3 and BiFe1-XCoXO3 nanostructure thin films were studied using FESEM, an increase in grain size was observed as Co concentration increases. The thickness of the nanostructure thin films was examined using FESEM cross-section. The EDX studies confirmed the elemental composition of the grown BiFeO3 and BiFe1-XCoXO3 nanostructure thin films. The optical characterizations of the grown nanostructure thin films were carried out using FTIR, it confirms the existence of Fe-O and Bi-O bands and UV-Visible spectroscopy shows the increase in optical band gap of the BiFeO3 nanostructure thin films with Co doping by ploting Tauc plot.

  13. Chitosan-Assisted Crystallization and Film Forming of Perovskite Crystals through Biomineralization.

    Science.gov (United States)

    Yang, Yang; Sun, Chen; Yip, Hin-Lap; Sun, Runcang; Wang, Xiaohui

    2016-03-18

    Biomimetic mineralization is a powerful approach for the synthesis of advanced composite materials with hierarchical organization and controlled structure. Herein, chitosan was introduced into a perovskite precursor solution as a biopolymer additive to control the crystallization and to improve the morphology and film-forming properties of a perovskite film by way of biomineralization. The biopolymer additive was able to control the size and morphology of the perovskite crystals and helped to form smooth films. The mechanism of chitosan-mediated nucleation and growth of the perovskite crystals was explored. As a possible application, the chitosan-perovskite composite film was introduced into a planar heterojunction solar cell and increased power conversion efficiency relative to that observed for the pristine perovskite film was achieved. The biomimetic mineralization method proposed in this study provides an alternative way of preparing perovskite crystals with well-controlled morphology and properties and extends the applications of perovskite crystals in photoelectronic fields, including planar-heterojunction solar cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Crystal orientation dependent thermoelectric properties of highly oriented aluminum-doped zinc oxide thin films

    KAUST Repository

    Abutaha, Anas I.; Sarath Kumar, S. R.; Alshareef, Husam N.

    2013-01-01

    We demonstrate that the thermoelectric properties of highly oriented Al-doped zinc oxide (AZO) thin films can be improved by controlling their crystal orientation. The crystal orientation of the AZO films was changed by changing the temperature

  15. Vibrational spectroscopy and analytical electron microscopy studies of Fe-V-O and In-V-O thin films

    CERN Document Server

    Vuk, A S; Drazic, G; Colomban, P

    2002-01-01

    Orthovanadate (M sup 3 sup + VO sub 4; M= Fe, In) and vanadate (Fe sub 2 V sub 4 O sub 1 sub 3) thin films were prepared using sol-gel synthesis and dip coating deposition. Using analytical electron microscopy (AEM), the chemical composition and the degree of crystallization of the phases present in the thin Fe-V-O films were investigated. TEM samples were prepared in both orientations: parallel (plan view) and perpendicular (cross section) to the substrate. In the first stages of crystallization, when the particle sizes were in the nanometer range, the classical identification of phases using electron diffraction was not possible. Instead of measuring d values, experimentally selected area electron diffraction (SAED) patterns were compared to calculated (simulated) patterns in order to determine the phase composition. The problems of evaluating the ratio of amorphous and crystalline phases in thin films are reported. Results of TEM and XRD as well as IR and Raman spectroscopy showed that the films made at lo...

  16. Crystal structure and thin film morphology of BBL ladder polymer

    Energy Technology Data Exchange (ETDEWEB)

    Song, H H [Department of Macromolecular Science, Han Nam University, Taejon (Korea, Republic of); Fratini, A V [Department of Chemistry, University of Dayton, Dayton, OH (United States); Chabinyc, M [Department of Chemistry, University of Dayton, Dayton, OH (United States); Price, G E [University of Dayton Research, Dayton, OH (United States); Agrawal, A K [Systran Corporation, Dayton, OH (United States); Wang, C S [University of Dayton Research, Dayton, OH (United States); Burkette, J [University of Dayton Research, Dayton, OH (United States); Dudis, D S [Materials Directorate, Wright Laboratory, Wright-Patterson Air Force Base, OH (United States); Arnold, F E [Materials Directorate, Wright Laboratory, Wright-Patterson Air Force Base, OH (United States)

    1995-03-01

    Crystal structure and morphology of poly[7-oxo-7H-benz(d,e)imidazo(4`,5`:5,6)-benzimidazo(2,1-a)isoquinoline-3,4:10,11-tetrayl-10-carbonyl] (BBL) ladder-like polymer were studied. The polymer forms a two-dimensional lattice of nematic liquid crystalline structure. An orthorhombic unit cell with cell parameters of a=7.87 b=3.37 c=11.97A was determined from the fiber diffraction pattern. In thin films, the rigid chains spontaneously form a layered structure across the film thickness, but in a very unusual manner, i.e. the very large molecular plane is standing perpendicularly to the film surface plane. The results are identical to our recent results of poly(p-phenylene benzobisthiazole) (PBT) film [7]. The polymer, however, lost its anisotropic order upon extrusion into a film and resulted in a fiber-like structure. (orig.)

  17. Molecular and electronic structure of thin films of protoporphyrin(IX)Fe(III)Cl

    Science.gov (United States)

    Snyder, Shelly R.; White, Henry S.

    1991-11-01

    Electrochemical, scanning tunneling microscopy (STM), and tunneling spectroscopy studies of the molecular and electronic properties of thin films of protoporphyrin(IX)Fe(III)Cl (abbreviated as PP(IX)Fe(III)Cl) on highly oriented pyrolytic graphite (HOPG) electrodes are reported. PP(IX)Fe(III)Cl films are prepared by two different methods: (1) adsorption, yielding an electrochemically-active film, and (2) irreversible electrooxidative polymerization, yielding an electrochemically-inactive film. STM images, in conjunction with electro-chemical results, indicate that adsorption of PP(IX)Fe(III)Cl from aqueous solutions onto freshly cleaved HOPG results in a film comprised of molecular aggregates. In contrast, films prepared by irreversible electrooxidative polymerization of PP(IX)Fe(III)Cl have a denser, highly structured morphology, including what appear to be small pinholes (approx. 50A diameter) in an otherwise continuous film.

  18. Crystallization of [Fe4S3]-ferredoxin from the hyperthermophile archaeon pyrococcus furiosus

    DEFF Research Database (Denmark)

    Nielsen, Michael Ericsson Skovbo; Harris, Pernille; Christensen, Hans Erik Mølager

    2003-01-01

    Recombinant Pyrococcus furiosus ferredoxin with a [Fe3S4]-cluster was crystallized through steps of optimization and X-ray diffraction data were collected from several crystal forms. Flat plate-like crystals were grown by hanging-drop vapour diffusion. The precipitant used was 30% PEG 400; the p...

  19. Soft magnetic properties of hybrid ferromagnetic films with CoFe, NiFe, and NiFeCuMo layers

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jong-Gu [Eastern-western Biomedical Engineering, Sangji University, Wonju 220-702 (Korea, Republic of); Hwang, Do-Guwn [Dept. of Oriental Biomedical Engineering, Sangji University, Wonju 220-702 (Korea, Republic of); Rhee, Jang-Roh [Dept. of Physics, Sookmyung Women' s University, Seoul 140-742 (Korea, Republic of); Lee, Sang-Suk, E-mail: sslee@sangji.ac.kr [Dept. of Oriental Biomedical Engineering, Sangji University, Wonju 220-702 (Korea, Republic of)

    2011-09-30

    Two-layered ferromagnetic alloy films (NiFe and CoFe) with intermediate NiFeCuMo soft magnetic layers of different thicknesses were investigated to understand the relationship between coercivity and magnetization process by taking into account the strength of hard-axis saturation field. The thickness dependence of H{sub EC} (easy-axis coercivity), H{sub HS} (hard-axis saturation field), and {chi} (susceptibility) of the NiFeCuMo thin films in glass/Ta(5 nm)/[CoFe or NiFe(5 nm-t/2)]/NiFeCuMo(t = 0, 4, 6, 8, 10 nm)/[CoFe or NiFe(5 nm-t/2)]/Ta(5 nm) films prepared using the ion beam deposition method was determined. The magnetic properties (H{sub EC}, H{sub HS}, and {chi}) of the ferromagnetic CoFe, NiFe three-layers with an intermediate NiFeCuMo super-soft magnetic layer were strongly dependent on the thickness of the NiFeCuMo layer.

  20. High field properties of superconducting BaFe{sub 2-x}Ni{sub x}As{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Richter, Stefan [Institute for Metallic Materials, IFW Dresden (Germany); Technical University Dresden (Germany); Kurth, Fritz; Grinenko, Vadim; Nielsch, Kornelius; Huehne, Ruben [Institute for Metallic Materials, IFW Dresden (Germany); Iida, Kazumasa [Nagoya University (Japan); Pervakov, Kirill [Russian Academy of Sciences (Russian Federation); Tarantini, Chiara; Jaroszynski, Jan [National High Magnetic Field Laboratory (United States); Pukenas, Aurimas; Skrotzki, Werner [Technical University Dresden (Germany)

    2016-07-01

    Fe based superconductors combine the advantages of cuprates (high upper critical field) with the small Hc{sub 2} anisotropy of classic low temperature superconductors, which makes them suitable candidates for high field applications. The study of Fe-based superconducting thin films is one crucial step to explore this potential in more detail. We present results for epitaxial BaFe{sub 2-x}Ni{sub x}As{sub 2} thin films, which have been successfully grown for the first time using pulsed laser deposition. Superconducting transition temperatures of up to 19 K have been realized in slightly overdoped films, which is in good agreement with results obtained for single crystals. The behavior of the upper critical field and critical current density has been measured in high magnetic fields up to 35 T. The results will be correlated to the observed microstructure and compared to high field data for single crystals with similar composition.

  1. Tunable magnetic properties by interfacial manipulation of L1(0)-FePt perpendicular ultrathin film with island-like structures.

    Science.gov (United States)

    Feng, C; Wang, S G; Yang, M Y; Zhang, E; Zhan, Q; Jiang, Y; Li, B H; Yu, G H

    2012-02-01

    Based on interfacial manipulation of the MgO single crystal substrate and non-magnetic AIN compound, a L1(0)-FePt perpendicular ultrathin film with the structure of MgO/FePt-AIN/Ta was designed, prepared, and investigated. The film is comprised of L1(0)-FePt "magnetic islands," which exhibits a perpendicular magnetic anisotropy (PMA), tunable coercivity (Hc), and interparticle exchange coupling (IEC). The MgO substrate promotes PMA of the film because of interfacial control of the FePt lattice orientation. The AIN compound is doped to increase the difference of surface energy between FePt layer and MgO substrate and to suppress the growth of FePt grains, which takes control of island growth mode of FePt atoms. The AIN compound also acts as isolator of L1(0)-FePt islands to pin the sites of FePt domains, resulting in the tunability of Hc and IEC of the films.

  2. Liquid crystals for organic thin-film transistors

    Science.gov (United States)

    Iino, Hiroaki; Usui, Takayuki; Hanna, Jun-Ichi

    2015-04-01

    Crystalline thin films of organic semiconductors are a good candidate for field effect transistor (FET) materials in printed electronics. However, there are currently two main problems, which are associated with inhomogeneity and poor thermal durability of these films. Here we report that liquid crystalline materials exhibiting a highly ordered liquid crystal phase of smectic E (SmE) can solve both these problems. We design a SmE liquid crystalline material, 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-10), for FETs and synthesize it. This material provides uniform and molecularly flat polycrystalline thin films reproducibly when SmE precursor thin films are crystallized, and also exhibits high durability of films up to 200 °C. In addition, the mobility of FETs is dramatically enhanced by about one order of magnitude (over 10 cm2 V-1 s-1) after thermal annealing at 120 °C in bottom-gate-bottom-contact FETs. We anticipate the use of SmE liquid crystals in solution-processed FETs may help overcome upcoming difficulties with novel technologies for printed electronics.

  3. Magnetic studies of Fe-Y compositionally modulated thin films

    International Nuclear Information System (INIS)

    Badia, F.; Ferrater, C.; Lousa, A.; Martinez, B.; Labarta, A.; Tejada, J.

    1990-01-01

    Compositionally modulated thin films of Y/Fe have been studied by using SQUID magnetometry. Samples were grown by electron-beam evaporation onto Kapton substrates. In the low applied field regime, the samples show irreversible behavior when they are submitted to ZFC-FC magnetization processes, increasing the irreversibility zone as the thickness of the Fe layers increases. In the high applied magnetic field regime (H≥10 000 Oe), samples show ferromagnetic behavior. The temperature dependence of the saturation magnetization has been studied, and it was found that both spin-wave excitations and Stoner excitations occur at temperatures higher than 40 K, and a marked deviation from the T 3/2 law was noted below 30 K

  4. Stress impedance effects in flexible amorphous FeCoSiB magnetoelastic films

    International Nuclear Information System (INIS)

    Zhang Wanli; Peng Bin; Su Ding; Tang Rujun; Jiang Hongchuan

    2008-01-01

    Amorphous FeCoSiB films were deposited on the flexible polyimide substrates (Kapton type (VN)) by DC magnetron sputtering. Stress impedance (SI) effects of the flexible amorphous FeCoSiB magnetoelastic films were investigated in details. The results show that a large stress impedance effect can be observed in the flexible amorphous FeCoSiB magnetoelastic films. And the results also show a bias magnetic field plays an important role in the stress impedance of FeCoSiB films. Applied a bias magnetic field during depositing can induce obvious in-plane anisotropy in the FeCoSiB films, and a larger SI effect can be obtained with a stronger anisotropy in FeCoSiB films. Argon pressure has a significant effect on the SI effect of the FeCoSiB films. The SI of the FeCoSiB films reaches a maximum of 7.6% at argon pressure of 1.5 Pa, which can be explained by the change of residual stress in FeCoSiB films

  5. Synthesis, nanostructure and magnetic properties of FeCo-reduced graphene oxide composite films by one-step electrodeposition

    International Nuclear Information System (INIS)

    Cao, Derang; Li, Hao; Wang, Zhenkun; Wei, Jinwu; Wang, Jianbo; Liu, Qingfang

    2015-01-01

    FeCo-reduced graphene oxide (FeCo-RGO) composite film was fabricated on indium tin oxide substrate using one-step electrodeposition method. Raman spectroscopy and field emission scanning electron microscope results show that the reduced graphene oxide is coprecipitated with the FeCo film. The energy-dispersive spectrometer results demonstrate that the atomic ratio of Fe/Co in FeCo-RGO composite film is larger than that of the FeCo film under the same fabrication condition. As a result, the FeCo-RGO composite film exhibits good soft magnetic properties and high-frequency properties as well as the FeCo film. The magnetic anisotropy field and saturation magnetization of FeCo-RGO composite film are increased when compared with FeCo film. Furthermore, the ferromagnetic resonance frequency is improved from 2.15 GHz for the FeCo film to 3.9 GHz for the FeCo-RGO composite film. - Highlights: • FeCo-reduced graphene oxide composite film was fabricated on indium tin oxide substrate. • One step electrodeposition method was used. • Good soft magnetic properties were exhibited by the composite films. • Increase of resonance frequency from 2.15 GHz for FeCo film to 3.9 GHz for composite film

  6. Effect of γ-(Fe,Ni) crystal-size stabilization in Fe-Ni-B amorphous ribbon

    Science.gov (United States)

    Gorshenkov, M. V.; Glezer, A. M.; Korchuganova, O. A.; Aleev, A. A.; Shurygina, N. A.

    2017-02-01

    The effect of stabilizing crystal size in a melt-quenched amorphous Fe50Ni33B17 ribbon is described upon crystallization in a temperature range of 360-400°C. The shape, size, volume fraction, and volume density have been investigated by transmission electron microscopy and X-ray diffraction methods. The formation of an amorphous layer of the Fe50Ni29B21 compound was found by means of atomic-probe tomography at the boundary of the crystallite-amorphous phase. The stabilization of crystal sizes during annealing is due to the formation of a barrier amorphous layer that has a crystallization temperature that exceeds the crystallization temperature of the matrix amorphous alloy.

  7. Raman analysis of gold on WSe2 single crystal film

    International Nuclear Information System (INIS)

    Mukherjee, Bablu; Sun Leong, Wei; Li, Yida; Thong, John T L; Gong, Hao; Sun, Linfeng; Xiang Shen, Ze; Simsek, Ergun

    2015-01-01

    Synthesis and characterization of high-quality single-crystal tungsten diselenide (WSe 2 ) films on a highly insulating substrate is presented. We demonstrate for the first time that the presence of gold (Au) nanoparticles in the basal plane of a WSe 2 film can enhance its Raman scattering intensity. The experimentally observed enhancement ratio in the Raman signal correlates well with the simulated electric field intensity using both three-dimensional electromagnetic software and theoretical calculation considering layered medium coupled-dipole approximation (LM-CDA). This work serves as a guideline for the use of Au nanoparticles on WSe 2 single-crystal thin films for surface enhanced Raman scattering (SERS) applications in the future. (paper)

  8. Phase diagram of Fe1-xCox ultrathin film

    International Nuclear Information System (INIS)

    Fridman, Yu.A.; Klevets, Ph.N.; Voytenko, A.P.

    2008-01-01

    Concentration-driven reorientation phase transitions in ultrathin magnetic films of FeCo alloy have been studied. It is established that, in addition to the easy-axis and easy-plane phases, a spatially inhomogeneous phase (domain structure), a canted phase, and also an 'in-plane easy-axis' phase can exist in the system. The realization of the last phase is associated with the competition between the single-ion anisotropy and the magnetoelastic interaction. The critical values of Co concentration corresponding to the phase transitions are evaluated, the types of phase transitions are determined, and the phase diagrams are constructed

  9. Growth and characterizations of Ba2Ti2Fe2As4O single crystals

    Directory of Open Access Journals (Sweden)

    Yun-Lei Sun, Abduweli Ablimit, Jin-Ke Bao, Hao Jiang, Jie Zhou and Guang-Han Cao

    2013-01-01

    Full Text Available Single crystals of a new iron-based superconductor Ba2Ti2Fe2As4O have been grown successfully via a Ba2As3-flux method in a sealed evacuated quartz tube. Bulk superconductivity with Tc ~ 21.5 K was demonstrated in resistivity and magnetic susceptibility measurements after the as-grown crystals were annealed at 500 °C in vacuum for a week. X-ray diffraction patterns confirm that the annealed and the as-grown crystals possess the identical crystallographic structure of Ba2Ti2Fe2As4O. Energy-dispersive x-ray spectra indicate that partial Ti/Fe substitution exists in the [Fe2As2] layers and the annealing process redistributes the Ti within the Fe-plane. The ordered Fe-plane stabilized by annealing exhibits superconductivity with magnetic vortex pinned by Ti.

  10. Raman scattering in La1-xSrxFeO3-δ thin films: annealing-induced reduction and phase transformation

    Science.gov (United States)

    Islam, Mohammad A.; Xie, Yujun; Scafetta, Mark D.; May, Steven J.; Spanier, Jonathan E.

    2015-04-01

    Raman scattering in thin film La0.2Sr0.8FeO3-δ on MgO(0 0 1) collected at 300 K after different stages of annealing at selected temperatures T (300 K topotactic transformation of the crystal structure from that of the rhombohedral ABO3 perovskites to that of Brownmillerite-like structure consisting of octahedrally and tetrahedrally coordinated Fe atoms.

  11. Unique Crystal Orientation of Poly(ethylene oxide) Thin Films by Crystallization Using a Thermal Gradient

    DEFF Research Database (Denmark)

    Gbabode, Gabin; Delvaux, Maxime; Schweicher, Guillaume

    2017-01-01

    Poly(ethylene oxide), (PEO), thin films of different thicknesses (220, 450, and 1500 nm) and molecular masses (4000, 8000, and 20000 g/mol) have been fabricated by spin-coating of methanol solutions onto glass substrates. All these samples have been recrystallized from the melt using a directional......, to significantly decrease the distribution of crystal orientation obtained after crystallization using the thermal gradient technique....

  12. Capping layer-tailored interface magnetic anisotropy in ultrathin Co2FeAl films

    International Nuclear Information System (INIS)

    Belmeguenai, M.; Zighem, F.; Chérif, S. M.; Gabor, M. S.; Petrisor, T.; Tiusan, C.

    2015-01-01

    Co 2 FeAl (CFA) thin films of various thicknesses (2 nm ≤ d ≤ 50 nm) have been grown on (001) MgO single crystal substrates and then capped with Cr, V, and Ta. Their magnetic and structural properties have been studied by x-ray diffraction (XRD), vibrating sample magnetometry, and broadband microstrip ferromagnetic resonance (MS-FMR). The XRD revealed that the films are epitaxial with the cubic [001] CFA axis normal to the substrate plane and that the chemical order varies from the B2 phase to the A2 phase when decreasing the thickness. The deduced lattice parameters showed that the Cr-capped films exhibit a larger tetragonal distortion, as compared with the films capped with V or Ta. The presence of magnetic dead layers has been observed in CFA samples capped with V and Ta but not in the case of the Cr-capped ones. The effective magnetization, deduced from the fit of MS-FMR measurements, increases (decreases) linearly with the CFA inverse thickness (1/d) for the Cr-capped (Ta-capped) films while it is constant for the V-capped ones. This allows quantifying the perpendicular surface anisotropy coefficients of −0.46 erg/cm 2 and 0.74 erg/cm 2 for Cr and Ta-capped films, respectively. Moreover, the fourfold and the uniaxial anisotropy fields, measured in these films, showed different trends with a respect to the CFA inverse thickness. This allows inferring that a non-negligible part of the fourfold magnetocrystalline term is of interfacial origin

  13. Photoelectrochemical Performance Observed in Mn-Doped BiFeO3 Heterostructured Thin Films

    Directory of Open Access Journals (Sweden)

    Hao-Min Xu

    2016-11-01

    Full Text Available Pure BiFeO3 and heterostructured BiFeO3/BiFe0.95Mn0.05O3 (5% Mn-doped BiFeO3 thin films have been prepared by a chemical deposition method. The band structures and photosensitive properties of these films have been investigated elaborately. Pure BiFeO3 films showed stable and strong response to photo illumination (open circuit potential kept −0.18 V, short circuit photocurrent density was −0.023 mA·cm−2. By Mn doping, the energy band positions shifted, resulting in a smaller band gap of BiFe0.95Mn0.05O3 layer and an internal field being built in the BiFeO3/BiFe0.95Mn0.05O3 interface. BiFeO3/BiFe0.95Mn0.05O3 and BiFe0.95Mn0.05O3 thin films demonstrated poor photo activity compared with pure BiFeO3 films, which can be explained by the fact that Mn doping brought in a large amount of defects in the BiFe0.95Mn0.05O3 layers, causing higher carrier combination and correspondingly suppressing the photo response, and this negative influence was more considerable than the positive effects provided by the band modulation.

  14. Formation and stability of Fe-rich precipitates in dilute Zr(Fe) single-crystal alloys

    International Nuclear Information System (INIS)

    Zou, H.; Hood, G.M.; Roy, J.A.; Schultz, R.J.

    1993-02-01

    The formation and stability of Fe-rich precipitates in two α-Zr(Fe) single-crystal alloys with nominal compositions (I, 50 ppma Fe, and II, 650 ppma Fe) have been investigated (the maximum solid solubility of Fe in α-Zr is 180 ppma - 800 C). Optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been used to examine the characteristics of Fe-rich precipitates. SEM and TEM micrographs show that in as-grown alloy II, Zr 2 Fe precipitates are located at 'stringers'. Precipitates were not observed in as-grown alloy I. During annealing, below the solvus, Fe diffuses to the surfaces to form Zr 3 Fe precipitates in both alloys. The precipitates on the surfaces of alloy I tend to be star-like (0001) or pyramidal (1010), and their distribution is heterogeneous. Dissolution of Zr 3 Fe surface precipitates of alloy I (annealing above the solvus) leaves precipitate-like features on the surfaces. Zr 2 Fe precipitates in as-grown alloy II can be dissolved only by β-phase annealing. (Author) 8 figs., 18 refs

  15. Heterogeneous bilayer films NiFe (Fe)-Dy: magnetic circular dichroism and Dy spin ordering

    Energy Technology Data Exchange (ETDEWEB)

    Markov, V.V. E-mail: ise@iph.krasn.ruise@iph.krasnoyarsk.su; Kesler, V.G.; Khudyakov, A.E.; Edelman, I.S.; Bondarenko, G.V

    2001-08-01

    Results of the magnetic circular dichroism (MCD) and Auger electron spectroscopy (AES) investigations in the 3d transition metal-Dy bi-layer films are presented. It is shown that even at room temperature the Dy layer makes a contribution to MCD of the bi-layer film, which corresponds to the MCD value in the single-layer Dy film measured below T{sub C}=85 K. According to the AES data there is no sharp interface between 3d and Dy layers in these films. Some amount of Ni and Fe atoms is dispersed in the Dy layer and some amount of Dy atoms is dispersed in the 3d layer. The comparison of the MCD and AES data allows one to suppose the Dy layer in the bi-layer films to be magnetically ordered at room temperature under the influence of the 3d-layer spin system. The influence spreads to long distances inside Dy layer through the 3d-ions dispersed in it.

  16. Heterogeneous bilayer films NiFe (Fe)-Dy: magnetic circular dichroism and Dy spin ordering

    International Nuclear Information System (INIS)

    Markov, V.V.; Kesler, V.G.; Khudyakov, A.E.; Edelman, I.S.; Bondarenko, G.V.

    2001-01-01

    Results of the magnetic circular dichroism (MCD) and Auger electron spectroscopy (AES) investigations in the 3d transition metal-Dy bi-layer films are presented. It is shown that even at room temperature the Dy layer makes a contribution to MCD of the bi-layer film, which corresponds to the MCD value in the single-layer Dy film measured below T C =85 K. According to the AES data there is no sharp interface between 3d and Dy layers in these films. Some amount of Ni and Fe atoms is dispersed in the Dy layer and some amount of Dy atoms is dispersed in the 3d layer. The comparison of the MCD and AES data allows one to suppose the Dy layer in the bi-layer films to be magnetically ordered at room temperature under the influence of the 3d-layer spin system. The influence spreads to long distances inside Dy layer through the 3d-ions dispersed in it

  17. Columnar grain growth of FePt(L10) thin films

    International Nuclear Information System (INIS)

    Yang En; Ho Hoan; Laughlin, David E.; Zhu Jiangang

    2012-01-01

    An experimental approach for obtaining perpendicular FePt-SiOx thin films with a large height to diameter ratio FePt(L1 0 ) columnar grains is presented in this work. The microstructure for FePt-SiOx composite thin films as a function of oxide volume fraction, substrate temperature, and film thickness is studied by plan view and cross section TEM. The relations between processing, microstructure, epitaxial texture, and magnetic properties are discussed. By tuning the thickness of the magnetic layer and the volume fraction of oxide in the film at a sputtering temperature of 410 deg. C, a 16 nm thick perpendicular FePt film with ∼8 nm diameter of FePt grains was obtained. The height to diameter ratio of the FePt grains was as large as 2. Ordering at lower temperature can be achieved by introducing a Ag sacrificial layer.

  18. Stepwise crystallization and the layered distribution in crystallization kinetics of ultra-thin poly(ethylene terephthalate) film

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, Biao, E-mail: chemizuo@zstu.edu.cn, E-mail: wxinping@yahoo.com; Xu, Jianquan; Sun, Shuzheng; Liu, Yue; Yang, Juping; Zhang, Li; Wang, Xinping, E-mail: chemizuo@zstu.edu.cn, E-mail: wxinping@yahoo.com [Department of Chemistry, Key Laboratory of Advanced Textile Materials and Manufacturing Technology of the Education Ministry, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

    2016-06-21

    Crystallization is an important property of polymeric materials. In conventional viewpoint, the transformation of disordered chains into crystals is usually a spatially homogeneous process (i.e., it occurs simultaneously throughout the sample), that is, the crystallization rate at each local position within the sample is almost the same. Here, we show that crystallization of ultra-thin poly(ethylene terephthalate) (PET) films can occur in the heterogeneous way, exhibiting a stepwise crystallization process. We found that the layered distribution of glass transition dynamics of thin film modifies the corresponding crystallization behavior, giving rise to the layered distribution of the crystallization kinetics of PET films, with an 11-nm-thick surface layer having faster crystallization rate and the underlying layer showing bulk-like behavior. The layered distribution in crystallization kinetics results in a particular stepwise crystallization behavior during heating the sample, with the two cold-crystallization temperatures separated by up to 20 K. Meanwhile, interfacial interaction is crucial for the occurrence of the heterogeneous crystallization, as the thin film crystallizes simultaneously if the interfacial interaction is relatively strong. We anticipate that this mechanism of stepwise crystallization of thin polymeric films will allow new insight into the chain organization in confined environments and permit independent manipulation of localized properties of nanomaterials.

  19. Mixed hyperfine interaction in amorphous Fe-Zr sputtered films in external magnetic field - a 57Fe Moessbauer study

    International Nuclear Information System (INIS)

    Fries, S.M.; Crummenauer, J.; Wagner, H.-G.; Gonser, U.; Chien, C.L.

    1986-01-01

    Conventional 57 Fe-Moessbauer spectroscopy provides only information about the magnitude of the splitting QS in the case of electric quadrupole hyperfine interaction, but not on the sign of the main component of the electric field gradient (EFG) or the asymmetry parameter which are sensitive to the local environment of the 57 Fe nuclei. This kind of information is obtained by measurements in external magnetic fields. In the case of amorphous Fe-Zr sputtered films mixed hyperfine interaction leads to a clear change in the behaviour of the Zr-rich and the Fe-rich alloys, indicating the existence of magnetic clusters in the Fe-rich samples. (Auth.)

  20. Structural and superconducting properties of epitaxial Fe{sub 1+y}Se{sub 1-x}Te{sub x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Richter, Stefan; Yuan, Feifei; Grinenko, Vadim; Huehne, Ruben [Institute for Metallic Materials, IFW Dresden (Germany); Sala, Alberto; Putti, Marina [Dipartimento di Fisica, Universita di Genova (Italy)

    2015-07-01

    The iron based superconductor Fe(Se,Te) is in the center of much ongoing research. The reason for this is on the one hand its simple crystal structure, that consists only of stacked Fe(Se,Te) layers so that structural and superconducting properties can be connected more easily, on the other hand FeSe itself shows a high sensibility for strain and changes in stoichiometry and can have potentially very high critical temperatures under hydrostatic pressure or in monolayers. We investigate epitaxial thin films of Fe{sub 1+y}Se{sub 1-x}Te{sub x} grown by pulsed laser deposition on different single crystalline substrates. A high crystalline quality and a superconducting transition of up to about 20 K can be achieved using optimized deposition parameters. The influence of growth conditions, Te-doping, film thickness and post growth oxygen treatment on the structural and superconducting properties on these films will be presented in detail.

  1. Observation of second spin reorientation transition within ultrathin region in Fe films on Ag(001) surface

    International Nuclear Information System (INIS)

    Khim, T.-Y.; Shin, M.; Lee, H.; Park, B.-G.; Park, J.-H.

    2014-01-01

    We acquired direct measurements for in-plane and perpendicular-to-plane magnetic moments of Fe films using an x-ray magnetic circular dichroism technique with increase of the Fe thickness (up to 40 Å) on the Ag(001) surface. Epitaxial Fe/Ag(001) films were grown in situ with the thickness varying from 2 Å to 40 Å, and the magnetic anisotropy was carefully investigated as a function of the film thickness. We found re-entrance of the in-plane magnetic anisotropy of the Fe film in ultrathin region. The results manifest that the epitaxial Fe/Ag(001) film undergoes two distinct spin reorientation transitions from in-plane to out-of-plane at the film thickness t ≈ 9 Å and back to in-plane at t ≈ 18 Å as t increases.

  2. Magnetic SiO2/Fe3O4 colloidal crystals

    International Nuclear Information System (INIS)

    Huang, C-K; Hou, C-H; Chen, C-C; Tsai, Y-L; Chang, L-M; Wei, H-S; Hsieh, K-H; Chan, C-H

    2008-01-01

    We proposed a novel technique to fabricate colloidal crystals by using monodisperse SiO 2 coated magnetic Fe 3 O 4 (SiO 2 /Fe 3 O 4 ) microspheres. The magnetic SiO 2 /Fe 3 O 4 microspheres with a diameter of 700 nm were synthesized in the basic condition with ferric sulfate, ferrous sulfate, tartaric acid and tetraethyl orthosilicate (TEOS) in the reaction system. Monodisperse SiO 2 /Fe 3 O 4 superparamagnetic microspheres have been successfully used to fabricate colloidal crystals under the existing magnetic field

  3. Structure, magnetism, and interface properties of epitactical thin Fe and FePt films on GaAs(001) substrates; Struktur, Magnetismus und Grenzflaecheneigenschaften epitaktischer duenner Fe- und FePt-Filme auf GaAs(001)-Substraten

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, Ellen Ursula

    2007-12-17

    The research in this thesis is focused on the study of the Fe spin structure and interface magnetism of thin epitaxial Fe layers or epitaxial FePt alloy films with chemical L1{sub 0} order on GaAs(001) surfaces. The main method of investigation was isotope-specific conversion electron Moessbauer spectroscopy (CEMS) combined with the {sup 57}Fe probe-layer technique in the temperature range of 4.2-300 K. The film structure was studied using electron diffraction (RHEED) and X-ray diffraction (XRD). The chemical order parameter S determined by XRD was found to increase with rising growth temperature, T{sub S}, to a maximum value of 0.71, until long range order is destroyed at T{sub S}>350 C by alloying with the substrate. As an important result a linear correlation between short-range order (revealed by the relative spectral area of the L1{sub 0} phase) and long-range order S was observed. The observed perpendicular Fe spin texture, characterized by the mean tilting angle left angle {theta} right angle of the Fe spins (relative to the film normal direction), was found to correlate with the L1{sub 0} phase content and with S. Furthermore, epitaxial Fe(001) films on GaAs(001)-(4 x 6) and on GaAs(001)-LED surfaces were grown successfully. In the initial stage of Fe film growth non-monotonous behavior of the in-plane lattice parameter was observed by RHEED. The magnetic hyperfine field distributions P(B{sub hf}) at the Fe/GaAs interface extracted from CEMS spectra for T{sub S}=-140 C or room temperature (RT) were found to be very similar. The observed large mean hyperfine fields of left angle B{sub hf} right angle {approx}25-27 T at the interface indicate the presence of high average Fe moments of 1.7-1.8 {mu}{sub B}. Nonmagnetic interface layers either can be excluded (Fe/GaAs) or are very thin (0.5 ML,Fe/GaAs-LED). Owing to its island structure an ultrathin (1.9 ML thick) uncoated Fe(001) film on GaAs(001)-(4 x 6) shows superparamagnetism with a blocking temperature of

  4. Diffusion and crystal growth in plasma deposed thin ITO films

    International Nuclear Information System (INIS)

    Steffen, H.; Wulff, H.; Quaas, M.; Tun, Tin Maung.; Hipple, R.

    2000-01-01

    Tin-doped indium oxide (ITO) films were deposited by means of DC-planar magnetron sputtering. A metallic In/Sn (90/10) target an Ar/O 2 gas mixture were used. The oxygen flow was varied between 0 and 2 sccm. Substrate voltages between 0 and -100 V were used. With increasing oxygen flow film structure and composition change from crystalline metallic In/Sn to amorphous ITO. Simultaneously the deposition rate decreases and the film density increases. The diffusion of oxygen into metallic In/Sn films and the amorphous-to-crystalline transformation of ITO were studied using in situ grazing incidence X-ray diffractometry (GIXRD), grazing incidence reflectometry (GIXR), and AFM. From the X-ray integral intensities diffusion constants, activation energies of the diffusion, reaction order and activation energy of the crystal growth were extracted. (authors)

  5. Crystallization of Electrodeposited Germanium Thin Film on Silicon (100).

    Science.gov (United States)

    Abidin, Mastura Shafinaz Zainal; Matsumura, Ryo; Anisuzzaman, Mohammad; Park, Jong-Hyeok; Muta, Shunpei; Mahmood, Mohamad Rusop; Sadoh, Taizoh; Hashim, Abdul Manaf

    2013-11-06

    We report the crystallization of electrodeposited germanium (Ge) thin films on n-silicon (Si) (100) by rapid melting process. The electrodeposition was carried out in germanium (IV) chloride: propylene glycol (GeCl₄:C₃H₈O₂) electrolyte with constant current of 50 mA for 30 min. The measured Raman spectra and electron backscattering diffraction (EBSD) images show that the as-deposited Ge thin film was amorphous. The crystallization of deposited Ge was achieved by rapid thermal annealing (RTA) at 980 °C for 1 s. The EBSD images confirm that the orientations of the annealed Ge are similar to that of the Si substrate. The highly intense peak of Raman spectra at 300 cm -1 corresponding to Ge-Ge vibration mode was observed, indicating good crystal quality of Ge. An additional sub peak near to 390 cm -1 corresponding to the Si-Ge vibration mode was also observed, indicating the Ge-Si mixing at Ge/Si interface. Auger electron spectroscopy (AES) reveals that the intermixing depth was around 60 nm. The calculated Si fraction from Raman spectra was found to be in good agreement with the value estimated from Ge-Si equilibrium phase diagram. The proposed technique is expected to be an effective way to crystallize Ge films for various device applications as well as to create strain at the Ge-Si interface for enhancement of mobility.

  6. Crystallization of Electrodeposited Germanium Thin Film on Silicon (100

    Directory of Open Access Journals (Sweden)

    Abdul Manaf Hashim

    2013-11-01

    Full Text Available We report the crystallization of electrodeposited germanium (Ge thin films on n-silicon (Si (100 by rapid melting process. The electrodeposition was carried out in germanium (IV chloride: propylene glycol (GeCl4:C3H8O2 electrolyte with constant current of 50 mA for 30 min. The measured Raman spectra and electron backscattering diffraction (EBSD images show that the as-deposited Ge thin film was amorphous. The crystallization of deposited Ge was achieved by rapid thermal annealing (RTA at 980 °C for 1 s. The EBSD images confirm that the orientations of the annealed Ge are similar to that of the Si substrate. The highly intense peak of Raman spectra at 300 cm−1 corresponding to Ge-Ge vibration mode was observed, indicating good crystal quality of Ge. An additional sub peak near to 390 cm−1 corresponding to the Si-Ge vibration mode was also observed, indicating the Ge-Si mixing at Ge/Si interface. Auger electron spectroscopy (AES reveals that the intermixing depth was around 60 nm. The calculated Si fraction from Raman spectra was found to be in good agreement with the value estimated from Ge-Si equilibrium phase diagram. The proposed technique is expected to be an effective way to crystallize Ge films for various device applications as well as to create strain at the Ge-Si interface for enhancement of mobility.

  7. Epitaxial growth of Fe-based superconductor thin films

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Sven; Haenisch, Jens; Holzapfel, Bernhard [Institut fuer Technische Physik, Karlsruher Institut fuer Technologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2016-07-01

    The Fe-based superconductors (FBS), discovered in 2008, are not only interesting for possible applications due to their large upper critical fields and low anisotropies, but also for basic understanding of unconventional superconductivity. With their properties, they constitute a link between the classic low-T{sub c} superconductors (low anisotropies, low thermal fluctuations, s-wave type symmetry) and the oxocuprates (T{sub c} up to 55 K, large H{sub c2}, unconventional pairing). Their multi-band nature reminds of MgB{sub 2}. We prepare thin films of FBS in the so called 122 family, namely Co- and P-doped BaFe{sub 2}As{sub 2} to investigate application relevant properties, such as critical current density J{sub c}, by pulsed laser deposition using a frequency-tripled Nd:YAG laser (λ = 355 nm). Microstructure and chemical composition will be investigated by XRD, AFM and SEM, and electrical transport using a 14 T PPMS. The results are compared to literature data on films grown at different wavelengths.

  8. Magnetoresistance and magnetostriction of Ni81Fe19 and Co90Fe10 mono- and bilayer films

    International Nuclear Information System (INIS)

    Sahingoz, R.; Hollingworth, M.P.; Gibbs, M.R.J.; Murdoch, S.J.

    2005-01-01

    Monolayer and bilayer films of Ni 81 Fe 19 , Co 90 Fe 10 , Co 90 Fe 10 /Ni 81 Fe 19 , and Ni 81 Fe 19 /Co 90 Fe 10 have been grown on thermally oxidized Si. The magnetoresistance (MR) of the samples was measured as a function of applied DC magnetic field, using a four-point probe method. The magnetostriction constant, λ s , was derived from the change of anisotropy field as a function of strain. The dependence of the MR on different combinations of film layers was investigated. The magnetoresistance of the bilayers changed dramatically upon reversal of the layer order. The mono- and bilayer samples with the same material on top of the substrate showed similar MR loop shapes. However, the saturation fields of the bilayers were larger than those for the monolayers. The magnetostriction of all samples was negative. We discuss the consequences for the study and optimization of spin-valve devices

  9. Precipitation of thin-film organic single crystals by a novel crystal growth method using electrospray and ionic liquid film

    Science.gov (United States)

    Ueda, Hiroyuki; Takeuchi, Keita; Kikuchi, Akihiko

    2018-04-01

    We report an organic single crystal growth technique, which uses a nonvolatile liquid thin film as a crystal growth field and supplies fine droplets containing solute from the surface of the liquid thin film uniformly and continuously by electrospray deposition. Here, we investigated the relationships between the solute concentration of the supplied solution and the morphology and size of precipitated crystals for four types of fluorescent organic low molecule material [tris(8-hydroxyquinoline)aluminum (Alq3), 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), N,N‧-bis(3-methylphenyl)-N,N‧-diphenylbenzidine (TPD), and N,N-bis(naphthalene-1-yl)-N,N-diphenyl-benzidine (NPB)] using an ionic liquid as the nonvolatile liquid. As the concentration of the supplied solution decreased, the morphology of precipitated crystals changed from dendritic or leaf shape to platelike one. At the solution concentration of 0.1 mg/ml, relatively large platelike single crystals with a diagonal length of over 100 µm were obtained for all types of material. In the experiment using ionic liquid and dioctyl sebacate as nonvolatile liquids, it was confirmed that there is a clear positive correlation between the maximum volume of the precipitated single crystal and the solubility of solute under the same solution supply conditions.

  10. High quality β-FeSi2 thin films prepared on silicon (100) by using pulsed laser ablation of Fe target

    International Nuclear Information System (INIS)

    Xu, S.C.; Yang, C.; Liu, M.; Jiang, S.Z.; Ma, Y.Y.; Chen, C.S.; Gao, X.G.; Sun, Z.C.; Hu, B.; Wang, C.C.; Man, B.Y.

    2012-01-01

    High quality β-FeSi 2 thin films have been fabricated on silicon (100) substrate by the pulsed laser deposition (PLD) technique with the Fe and sintered FeSi 2 targets. The crystalline quality and surface morphology of the samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. These results indicate that the samples prepared with a Fe target can acquire a better crystalline quality and a smoother surface than those with a sintered FeSi 2 target. The reasons were discussed with subsurface superheating mechanism. The intrinsic PL spectrum attributed to the interband transition of β-FeSi 2 for all the samples was compared, showing that the film prepared with Fe target can acquire a good PL property by optimizing experimental parameters. It is suggested that sputtering Fe on Si substrate by the pulsed laser offers a cheap and convenient way to prepare the β-FeSi 2 thin films. -- Highlights: ► β-FeSi 2 films were fabricated by PLD technique with the Fe and FeSi 2 targets. ► The films prepared with Fe target have good crystalline quality and smooth surface. ► The Fe target prepared film acquired a high PL intensity. ► Sputtering Fe on Si substrate offers a convenient way to prepare the β-FeSi 2 films.

  11. Crystallization of Fe83B17 amorphous alloy by electric pulses produced by a capacitor discharge

    International Nuclear Information System (INIS)

    Georgarakis, Konstantinos; Dudina, Dina V.; Mali, Vyacheslav I.; Anisimov, Alexander G.; Bulina, Natalia V.; Moreira Jorge, Alberto Jr.; Yavari, Alain R.

    2015-01-01

    Heating of conductive materials by electric current is used in many technological processes. Application of electric pulses to metallic glasses induces their fast crystallization, which is an interesting and complex phenomenon. In this work, crystallization of the Fe 83 B 17 amorphous alloy induced by pulses of electric current produced has been studied using X-ray diffraction and transmission electron microscopy. Ribbons of the alloy were directly subjected to single pulses of electric current 250 μs long formed by a capacitor discharge. As the value of ∫I 2 dt was increased from 0.33 to 2.00 A 2 s, different crystallization stages could be observed. The crystallization began through the formation of the nuclei of α-Fe. At high values of ∫I 2 dt, α-Fe and tetragonal and orthorhombic Fe 3 B and Fe 23 B 6 were detected in the crystallized ribbons with crystallites of about 50 nm. Thermal annealing of the ribbons at 600 C for 2 min resulted in the formation of α-Fe and tetragonal Fe 3 B. It was concluded that pulses of electric current produced by a capacitor discharge induced transformation of the Fe 83 B 17 amorphous phase into metastable crystalline products. (orig.)

  12. Hot plate annealing at a low temperature of a thin ferroelectric P(VDF-TrFE) film with an improved crystalline structure for sensors and actuators.

    Science.gov (United States)

    Mahdi, Rahman Ismael; Gan, W C; Abd Majid, W H

    2014-10-14

    Ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer 70/30 thin films are prepared by spin coating. The crystalline structure of these films is investigated by varying the annealing temperature from the ferroelectric phase to the paraelectric phase. A hot plate was used to produce a direct and an efficient annealing effect on the thin film. The dielectric, ferroelectric and pyroelectric properties of the P(VDF-TrFE) thin films are measured as a function of different annealing temperatures (80 to 140 °C). It was found that an annealing temperature of 100 °C (slightly above the Curie temperature, Tc) has induced a highly crystalline β phase with a rod-like crystal structure, as examined by X-ray. Such a crystal structure yields a high remanent polarization, Pr = 94 mC/m2, and pyroelectric constant, p = 24 μC/m2K. A higher annealing temperature exhibits an elongated needle-like crystal domain, resulting in a decrease in the crystalline structure and the functional electrical properties. This study revealed that highly crystalline P(VDF-TrFE) thin films could be induced at 100 °C by annealing the thin film with a simple and cheap method.

  13. Re-crystallization of ITO films after carbon irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Usman, Muhammad, E-mail: usmanm@ncp.edu.pk [Experimental Physics Laboratories, National Centre for Physics, Shahdara Valley Road, Quaid-i-Azam University, Islamabad (Pakistan); Khan, Shahid, E-mail: shahidkhan@zju.edu.cn [State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Khan, Majid [Department of Physics, Quaid-i-Azam University, Islamabad (Pakistan); Abbas, Turab Ali [Experimental Physics Laboratories, National Centre for Physics, Shahdara Valley Road, Quaid-i-Azam University, Islamabad (Pakistan)

    2017-01-15

    Highlights: • Carbon irradiation on ITO destroys crystal structure until threshold ion fluence. • Carbon irradiation induced amorphization in ITO is recoverable at higher fluence. • Optical transmittance is reduced after carbon irradiation. • Electrical resistivity is increased after irradiation with carbon ions in ITO. • Bandgap is reduced with increasing fluence of carbon irradiation. - Abstract: 2.0 MeV carbon ion irradiation effects on Indium Tin Oxide (ITO) thin films on glass substrate are investigated. The films are irradiated with carbon ions in the fluence range of 1 × 10{sup 13} to 1 × 10{sup 15} ions/cm{sup 2}. The irradiation induced effects in ITO are compared before and after ion bombardment by systematic study of structural, optical and electrical properties of the films. The XRD results show polycrystalline nature of un-irradiated ITO films which turns to amorphous state after 1 × 10{sup 13} ions/cm{sup 2} fluence of carbon ions. Further increase in ion fluence to 1 × 10{sup 14} ions/cm{sup 2} re-crystallizes the structure and retains for even higher fluences. A gradual decrease in the electrical conductivity and transmittance of irradiated samples is observed with increasing ion fluence. The band gap of the films is observed to be decreased after carbon irradiation.

  14. Re-crystallization of ITO films after carbon irradiation

    International Nuclear Information System (INIS)

    Usman, Muhammad; Khan, Shahid; Khan, Majid; Abbas, Turab Ali

    2017-01-01

    Highlights: • Carbon irradiation on ITO destroys crystal structure until threshold ion fluence. • Carbon irradiation induced amorphization in ITO is recoverable at higher fluence. • Optical transmittance is reduced after carbon irradiation. • Electrical resistivity is increased after irradiation with carbon ions in ITO. • Bandgap is reduced with increasing fluence of carbon irradiation. - Abstract: 2.0 MeV carbon ion irradiation effects on Indium Tin Oxide (ITO) thin films on glass substrate are investigated. The films are irradiated with carbon ions in the fluence range of 1 × 10"1"3 to 1 × 10"1"5 ions/cm"2. The irradiation induced effects in ITO are compared before and after ion bombardment by systematic study of structural, optical and electrical properties of the films. The XRD results show polycrystalline nature of un-irradiated ITO films which turns to amorphous state after 1 × 10"1"3 ions/cm"2 fluence of carbon ions. Further increase in ion fluence to 1 × 10"1"4 ions/cm"2 re-crystallizes the structure and retains for even higher fluences. A gradual decrease in the electrical conductivity and transmittance of irradiated samples is observed with increasing ion fluence. The band gap of the films is observed to be decreased after carbon irradiation.

  15. High-induction nanocrystalline soft magnetic Fe{sub X}Ti{sub Y}B{sub Z} films prepared by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Sheftel, Elena N.; Tedzhetov, Valentin A.; Harin, Eugene V.; Usmanova, Galina Sh. [A.A. Baikov Institute of Metallurgy and Material Science, Russian Academy of Sciences, Moscow (Russian Federation); Kiryukhantsev-Korneev, Filipp V. [National University of Science and Technology ' ' MISIS' ' , Moscow (Russian Federation)

    2016-12-15

    To design films with the Fe/TiB{sub 2} nanocomposite structure, which are characterized by high saturation induction B{sub s}, the phase and structural states and static magnetic properties of Fe-TiB{sub 2} films prepared by magnetron sputtering and subjected to subsequent annealing have been studied. According to X-ray diffraction data, either amorphous or nanocrystalline single-phase structure (an α-Fe(Ti,B) supersaturated solid solution with a bcc crystal lattice) is formed in the as-sputtered films. Depending on the film composition, the grain size of the α-Fe(Ti,B) phase varies from 45.6 to 6.5 nm; grains are characterized by high microstrain (0.21-4.96%). The annealing at 200-500 C leads to a decrease in the lattice parameter of the α-Fe(Ti,B) phase, i.e. to its depletion of titanium and boron and to the formation of two-phase α-Fe + Fe{sub 3}B structure after annealing at 500 C. The annealing at 200-500 C almost does not affect the grain size and microstrain of the bcc α-Fe-based phase. The amorphous state of the films is stable up to 500 C. All studied films are ferromagnets; the saturation induction B{sub s}(0.95-2.13 T) and coercive field H{sub c} (0.4-5 kA/m) of the films were determined. Correlations between the B{sub s} and H{sub c} magnitudes and the chemical composition of the films, their phase and structural states and magnetic structure are discussed. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. On the Relationship of Magnetocrystalline Anisotropy and Stoichiometry in Epitaxial L1{sub 0} CoPt(001) and FePt(001) Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Barmak, K

    2004-08-10

    Two series of epitaxial CoPt and FePt films, with nominal thicknesses of 42 or 50 nm, were prepared by sputtering onto single crystal MgO(001) substrates in order to investigate the chemical ordering and the resultant magnetic properties as a function of alloy composition. In the first series, the film composition was kept constant, while the substrate temperature was increased from 144 to 704 C. In the second series the substrate temperature was kept constant at 704 C for CoPt and 620 C for FePt, while the alloy stoichiometry was varied in the nominalrange of 40-60 at% Co(Fe). Film compositions and thicknesses were measured via Rutherford backscattering spectrometry. The lattice and long-range order parameter for the L1{sub 0} phase were obtained for both sets of films using x-ray diffraction. The room-temperature magnetocrystalline anisotropy constants were determined for a subset of the films using torque magnetometry. The order parameter was found to increase with increasing temperature, with ordering occurring more readily in FePt when compared with CoPt. A perpendicular anisotropy developed in CoPt for substrate temperatures above 534 C and in FePt above 321 C. The structure and width of the magnetic domains in CoPt and FePt, as seen by magnetic force microscopy, also demonstrated an increase in magnetic anisotropy with increasing temperature. For the films deposited at the highest temperatures (704 C for CoPt and 620 C for FePt), the order parameter reached a maximum near the equiatomic composition, whereas the magnetocrystalline anisotropy increased as the concentration of Co or Fe was increased from below to slightly above the equiatomic composition. It is concluded that non-stoichiometric L1{sub 0} CoPt and FePt, with a slight excess of Co or Fe, are preferable for applications requiring the highest anisotropies.

  17. Ion irradiation enhanced crystal nucleation in amorphous Si thin films

    International Nuclear Information System (INIS)

    Im, J.S.; Atwater, H.A.

    1990-01-01

    The nucleation kinetics of the amorphous-to-crystal transition of Si films under 1.5 MeV Xe + irradiation have been investigated by means of in situ transmission electron microscopy in the temperature range T=500--580 degree C. After an incubation period during which negligible nucleation occurs, a constant nucleation rate was observed in steady state, suggesting that homogeneous nucleation occurred. Compared to thermal crystallization, a significant enhancement in the nucleation rate during high-energy ion irradiation (five to seven orders of magnitude) was observed with an apparent activation energy of 3.9±0.75 eV

  18. Hydrothermal crystallization of amorphous titania films deposited using low temperature atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, D.R.G. [Institute of Materials Engineering, ANSTO, PMB 1, Menai, NSW 2234 (Australia)], E-mail: drm@ansto.gov.au; Triani, G.; Zhang, Z. [Institute of Materials Engineering, ANSTO, PMB 1, Menai, NSW 2234 (Australia)

    2008-10-01

    A two stage process (atomic layer deposition, followed by hydrothermal treatment) for producing crystalline titania thin films at temperatures compatible with polymeric substrates (< 130 deg. C) has been assessed. Titania thin films were deposited at 80 deg. C using atomic layer deposition. They were extremely flat, uniform and almost entirely amorphous. They also contained relatively high levels of residual Cl from the precursor. After hydrothermal treatment at 120 deg. C for 1 day, > 50% of the film had crystallized. Crystallization was complete after 10 days of hydrothermal treatment. Crystallization of the film resulted in the formation of coarse grained anatase. Residual Cl was completely expelled from the film upon crystallization. As a result of the amorphous to crystalline transformation voids formed at the crystallization front. Inward and lateral crystal growth resulted in voids being localized to the film/substrate interface and crystallite perimeters resulting in pinholing. Both these phenomena resulted in films with poor adhesion and film integrity was severely compromised.

  19. Infrared-active optical phonons in LiFePO4 single crystals

    Science.gov (United States)

    Stanislavchuk, T. N.; Middlemiss, D. S.; Syzdek, J. S.; Janssen, Y.; Basistyy, R.; Sirenko, A. A.; Khalifah, P. G.; Grey, C. P.; Kostecki, R.

    2017-07-01

    Infrared-active optical phonons were studied in olivine LiFePO4 oriented single crystals by means of both rotating analyzer and rotating compensator spectroscopic ellipsometry in the spectral range between 50 and 1400 cm-1. The eigenfrequencies, oscillator strengths, and broadenings of the phonon modes were determined from fits of the anisotropic harmonic oscillator model to the data. Optical phonons in a heterosite FePO4 crystal were measured from the delithiated ab-surface of the LiFePO4 crystal and compared with the phonon modes of the latter. Good agreement was found between experimental data and the results of solid-state hybrid density functional theory calculations for the phonon modes in both LiFePO4 and FePO4.

  20. Epitactical FeAl films on sapphire and their magnetic properties; Epitaktische FeAl-Filme auf Saphir und ihre magnetischen Eigenschaften

    Energy Technology Data Exchange (ETDEWEB)

    Trautvetter, Moritz

    2011-05-05

    In the presented thesis epitaxial FeAl thin films on sapphire have been prepared by pulse laser deposition (PLD). The thin films deposited at room temperature exhibits ferromagnetism and subsequent annealing is necessary to transform the thin films to paramagnetic B2-phase, where the transition temperature depends on the crystalline orientation of the sapphire substrate. Alternatively, by deposition at higher substrate temperature the B2-phase is obtained directly. However, morphology of the FeAl film is influenced by different growth modes resulting from different substrate temperatures. The paramagnetic FeAl films can then be transformed to ferromagnetic phase by successive ion irradiation. Independent of the ion species used for irradiation, the same universal relation between thin films' coercive fields and irradiation damage is identified. The ion irradiation ferromagnetism can be transformed back to paramagnetism by subsequent annealing. The mutual transition between ferromagnetic and paramagnetic phases has been performed several times and shows full reversibility. The ferromagnetic phase induced by Kr{sup +} irradiation exhibits structural relaxation, where the saturate magnetization of FeAl thin film gradually decreases in several days. Later, ion irradiation has been performed selectively on defined areas of the thin film with the help of an unconventional lithography technique. The subsequent thin film is composed of ordered hexagonal array of ferromagnetic nano-cylinders separated by a paramagnetic matrix, suggesting a promising system for magnetic data storage. (orig.)

  1. Investigation of electronic states of infinite-layer SrFeO2 epitaxial thin films by X-ray photoemission and absorption spectroscopies

    International Nuclear Information System (INIS)

    Chikamatsu, Akira; Matsuyama, Toshiya; Hirose, Yasushi; Kumigashira, Hiroshi; Oshima, Masaharu; Hasegawa, Tetsuya

    2012-01-01

    Highlights: ► Electronic states of infinite-layer SrFeO 2 films have been experimentally observed. ► Fe 3d states have higher densities of states in the valence-band region. ► Three peaks derived from Fe 3d states were observed in the conduction-band region. ► Indirect bandgap value was determined to be 1.3 eV. - Abstract: We investigated the electronic states of a single-crystal SrFeO 2 epitaxial thin film in the valence-band and conduction-band regions using synchrotron-radiation X-ray photoemission and absorption spectroscopies. Fe 2p–3d resonant photoemission measurements revealed that the Fe 3d states have higher densities of states at binding energies of 3–5 eV and 5–8.5 eV in the valence-band region. The O K-edge X-ray absorption spectrum exhibited three peaks in the Fe 3d-derived conduction band hybridized with O 2p states; these can be assigned to Fe 3d xy , 3d xz + 3d yz , and 3d x 2 –y 2 . In addition, the indirect bandgap value of the SrFeO 2 film was determined to be 1.3 eV by transmission and absorption spectroscopies.

  2. Structural and magnetic anisotropy in the epitaxial FeV2O4 (110) spinel thin films

    Science.gov (United States)

    Shi, Xiaolan; Wang, Yuhang; Zhao, Kehan; Liu, Na; Sun, Gaofeng; Zhang, Liuwan

    2015-11-01

    The epitaxial 200-nm-thick FeV2O4(110) films on (110)-oriented SrTiO3, LaAlO3 and MgAl2O4 substrates were fabricated for the first time by pulsed laser deposition, and the structural, magnetic, and magnetoresistance anisotropy were investigated systematically. All the films are monoclinic, whereas its bulk is cubic. Compared to FeV2O4 single crystals, films on SrTiO3 and MgAl2O4 are strongly compressively strained in [001] direction, while slightly tensily strained along normal [110] and in-plane [ 1 1 ¯ 0 ] directions. In contrast, films on LaAlO3 are only slightly distorted from cubic. The magnetic hard axis is in direction, while the easier axis is along normal [110] direction for films on SrTiO3 and MgAl2O4, and in-plane [ 1 1 ¯ 0 ] direction for films on LaAlO3. Magnetoresistance anisotropy follows the magnetization. The magnetic anisotropy is dominated by the magnetocrystalline energy, and tuned by the magneto-elastic coupling.

  3. Formation of β-FeSi 2 thin films by partially ionized vapor deposition

    Science.gov (United States)

    Harada, Noriyuki; Takai, Hiroshi

    2003-05-01

    The partially ionized vapor deposition (PIVD) is proposed as a new method to realize low temperature formation of β-FeSi 2 thin films. In this method, Fe is evaporated by E-gun and a few percents of Fe atoms are ionized. We have investigated influences of the ion content and the accelerating voltage of Fe ions on the structural properties of β-FeSi 2 films deposited on Si substrates. It was confirmed that β-FeSi 2 can be formed on Si(1 0 0) substrate by PIVD even at substrate temperature as low as 350, while FeSi by the conventional vacuum deposition. It was concluded that the influence of Fe ions on preferential orientation of β-FeSi 2 depends strongly on the content and the acceleration energy of ions.

  4. Formation of {beta}-FeSi{sub 2} thin films by partially ionized vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Harada, Noriyuki; Takai, Hiroshi

    2003-05-01

    The partially ionized vapor deposition (PIVD) is proposed as a new method to realize low temperature formation of {beta}-FeSi{sub 2} thin films. In this method, Fe is evaporated by E-gun and a few percents of Fe atoms are ionized. We have investigated influences of the ion content and the accelerating voltage of Fe ions on the structural properties of {beta}-FeSi{sub 2} films deposited on Si substrates. It was confirmed that {beta}-FeSi{sub 2} can be formed on Si(1 0 0) substrate by PIVD even at substrate temperature as low as 350, while FeSi by the conventional vacuum deposition. It was concluded that the influence of Fe ions on preferential orientation of {beta}-FeSi{sub 2} depends strongly on the content and the acceleration energy of ions.

  5. Very high coercivities of top-layer diffusion Au/FePt thin films

    International Nuclear Information System (INIS)

    Yuan, F.T.; Chen, S.K.; Liao, W.M.; Hsu, C.W.; Hsiao, S.N.; Chang, W.C.

    2006-01-01

    The Au/FePt samples were prepared by depositing a gold cap layer at room temperature onto a fully ordered FePt layer, followed by an annealing at 800 deg. C for the purpose of interlayer diffusion. After the deposition of the gold layer and the high-temperature annealing, the gold atoms do not dissolve into the FePt Ll 0 lattice. Compared with the continuous FePt film, the TEM photos of the bilayer Au(60 nm)/FePt(60 nm) show a granular structure with FePt particles embedded in Au matrix. The coercivity of Au(60 nm)/FePt(60 nm) sample is 23.5 kOe, which is 85% larger than that of the FePt film without Au top layer. The enhancement in coercivity can be attributed to the formation of isolated structure of FePt ordered phase

  6. Reactive Stresses in Ni49Fe18Ga27Co6 Shape-Memory-Alloy Single Crystals

    Science.gov (United States)

    Averkin, A. I.; Krymov, V. M.; Guzilova, L. I.; Timashov, R. B.; Soldatov, A. V.; Nikolaev, V. I.

    2018-03-01

    The reactive stresses induced in Ni49Fe18Ga27Co6-alloy single crystals during martensitic transformations with a limited possibility of shape-memory-strain recovery have been experimentally studied. The data on these crystals are compared with the results obtained previously for Cu-Al-Ni, Ni-Ti, and Ni‒Fe-Ga crystals. The potential of application of the Ni49Fe18Ga27Co6 single crystals in designing drives and power motors is demonstrated.

  7. Interfaces anisotropy in single crystal V/Fe/V trilayer

    Energy Technology Data Exchange (ETDEWEB)

    Louis, D. [Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, 54506 Vandoeuvre-lès-Nancy (France); Lytvynenko, Ia. [Sumy State University, 2, Rymskogo-Korsakova Street, 40007 Sumy (Ukraine); Hauet, T., E-mail: thomas.hauet@univ-lorraine.fr [Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, 54506 Vandoeuvre-lès-Nancy (France); Lacour, D.; Hehn, M.; Andrieu, S.; Montaigne, F. [Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, 54506 Vandoeuvre-lès-Nancy (France)

    2014-12-15

    The value and sign of V/Fe interface anisotropy are investigated. Epitaxial V/Fe/V/Au layers with different iron thicknesses were grown on single-crystalline (001) MgO substrate by ultra-high vacuum molecular beam epitaxy. Magnetometry was used to measure magnetization and out-of-plane anisotropy field. From these values, we quantify the number of dead layers due to V/Fe or Fe/V interfaces, and compare it with the literature. We deduce that dead layers occur mostly at the bottom V/Fe interface. An average value for V/Fe and Fe/V interface anisotropy around 0±0.1 erg/cm{sup 2} (mJ/m{sup 2}) was thus deduced. - Highlights: • In a V/Fe/V stack, dead layers (i.e. overall magnetization reduction) originate mostly from the bottom V/Fe interface. • The average value for V/Fe and Fe/V interface anisotropy in V/Fe/V stack has been quantified as 0±0.1 erg/cm{sup 2} (mJ/m{sup 2})

  8. Microstructure and magnetic properties of nanocomposite FePt/MgO and FePt/Ag films

    International Nuclear Information System (INIS)

    Chen, S.C.; Kuo, P.C.; Sun, A.C.; Chou, C.Y.; Fang, Y.H.; Wu, T.H.

    2006-01-01

    An in-plane magnetic anisotropy of FePt film is obtained in the MgO 5 nm/FePt t nm/MgO 5 nm films (where t=5, 10 and 20 nm). Both the in-plane coercivity (H c- parallel ) and the perpendicular magnetic anisotropy of FePt films are increased when introducing an Ag-capped layer instead of MgO-capped layer. An in-plane coercivity is 3154 Oe for the MgO 5 nm/FePt 10 nm/MgO 5 nm film, and it can be increased to 4846 Oe as a 5 nm Ag-capped layer instead of MgO-capped layer. The transmission electron microscopy (TEM)-energy disperse spectrum (EDS) analysis shows that the Ag mainly distributed at the grain boundary of FePt, that leads the increase of the grain boundary energy, which will enhance coercivity and perpendicular magnetic anisotropy of FePt film

  9. Polarized Raman study on the lattice structure of BiFeO3 films prepared by pulsed laser deposition

    KAUST Repository

    Yang, Yang; Yao, Yingbang; Zhang, Q.; Zhang, Xixiang

    2014-01-01

    Polarized Raman spectroscopy was used to study the lattice structure of BiFeO3 films on different substrates prepared by pulsed laser deposition. Interestingly, the Raman spectra of BiFeO3 films exhibit distinct polarization dependences

  10. Ab initio calculations of the electron spectrum and density of states of TlFeS{sub 2} and TlFeSe{sub 2} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Ismayilova, N. A., E-mail: ismayilova-narmin-84@mail.ru; Orudjev, H. S.; Jabarov, S. H. [Azerbaijan National Academy of Sciences, Institute of Physics (Azerbaijan)

    2017-04-15

    The results of ab initio calculations of the electron spectrum of TlFeS{sub 2} and TlFeSe{sub 2} crystals in the antiferromagnetic phase are reported. Calculations are carried out in the context of the density functional theory. The origin of the bands of s, p, and d electron states of Tl, Fe, S, and Se atoms is studied. It is established that, in the antiferromagnetic phase, the crystals possess semiconductor properties. The band gaps are found to be 0.05 and 0.34 eV for TlFeS{sub 2} and TlFeSe{sub 2} crystals, respectively.

  11. 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

  12. Microstructure and Magnetic Properties of NdFeB Films through Nd Surface Diffusion Process

    OpenAIRE

    Liu, Wenfeng; Zhang, Mingang; Zhang, Kewei; Chai, Yuesheng

    2017-01-01

    Ta/Nd/NdFeB/Nd/Ta films were deposited by magnetron sputtering on Si (100) substrates and subsequently annealed for 30 min at 923 K in vacuum. It was found that the microstructure and magnetic properties of Ta/Nd/NdFeB/Nd/Ta films strongly depend on the NdFeB layer thickness. With NdFeB layer thickness increasing, both the grain size and the strain firstly reduce and then increase. When NdFeB layer thickness is 750 nm, the strain reaches the minimum value. Meanwhile, both the in-plane and per...

  13. Multi-Valued Planar Hall Resistance Manipulated by Current Induced Magnetic Field in Fe Films Grown on GaAs(001) Substrates

    Science.gov (United States)

    Khym, Sungwon; Yoo, Taehee; Lee, Hakjoon; Lee, Sangyeop; Lee, Sanghoon; Liu, Xinyu; Furdyna, Jacek K.; Lee, Dong Uk; Kim, Eun Kyu

    2012-09-01

    A Hall device was fabricated from single-crystal Fe film having two in-plane magnetic easy axes. Planar Hall resistance measured by sequential application of current pulses to the metal strip that was deposited on the top of a Hall bar showed a hysteresis similar to that observed by scanning an external magnetic field. It was shown that discrete Hall resistance values in the hysteresis, which correspond to specific multidomain structures in Fe film, can be created by the application of appropriate sequences of current pulses to the metal strip, and can thus be used for read/write logic applications.

  14. Thin aligned organic polymer films for liquid crystal devices

    International Nuclear Information System (INIS)

    Foster, Kathryn Ellen

    1997-01-01

    This project was designed to investigate the possibility of producing alignment layers for liquid crystal devices by cross-linking thin films containing anisotropic polymer bound chromophores via irradiation with polarised ultraviolet light. Photocross-linkable polymers find use in microelectronics, liquid crystal displays, printing and UV curable lacquers and inks; so there is an increasing incentive for the development of new varieties of photopolymers in general. The synthesis and characterisation of two new photopolymers that are suitable as potential alignment layers for liquid crystal devices are reported in this thesis. The first polymer contains the anthracene chromophore attached via a spacer unit to a methacrylate backbone and the second used a similarly attached aryl azide group. Copolymers of the new monomers with methyl methacrylate were investigated to establish reactivity ratios in order to understand composition drift during polymerisation. (author)

  15. Fabrication of NdFeB microstructures using a silicon molding technique for NdFeB/Ta multilayered films and NdFeB magnetic powder

    International Nuclear Information System (INIS)

    Jiang Yonggang; Fujita, Takayuki; Uehara, Minoru; Iga, Yuki; Hashimoto, Taichi; Hao, Xiuchun; Higuchi, Kohei; Maenaka, Kazusuke

    2011-01-01

    The silicon molding technique is described for patterning of NdFeB/Ta multilayered magnetic films and NdFeB magnetic powder at the micron scale. Silicon trenches are seamlessly filled by 12-μm-thick NdFeB/Ta multilayered magnetic films with a magnetic retentivity of 1.3 T. The topography image and magnetic field distribution image are measured using an atomic force microscope and a magnetic force microscope, respectively. Using a silicon molding technique complemented by a lift-off process, NdFeB magnetic powder is utilized to fabricate magnetic microstructures. Silicon trenches as narrow as 20 μm are filled by a mixture of magnetic powder and wax powder. The B-H hysteresis loop of the patterned magnetic powder is characterized using a vibrating sample magnetometer, which shows a magnetic retentivity of approximately 0.37 T. - Highlights: → We demonstrate the fabrication of micro-magnets using silicon molding processes. → NdFeB/Ta films are well filled in silicon trenches with a thickness of 12 μm. → The 12-μm-thick NdFeB/Ta magnetic film shows a retentivity of 1.3 T. → Magnetic structures as narrow as 20 μm are fabricated using NdFeB magnetic powder. → VSM measurement shows a retentivity of 0.37 T for patterned NdFeB magnetic powder.

  16. Fabrication of NdFeB microstructures using a silicon molding technique for NdFeB/Ta multilayered films and NdFeB magnetic powder

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Yonggang, E-mail: yonggangj@gmail.com [School of Mechanical Engineering and Automation, Beihang University, Xueyuan Road No. 37, Haidian District, Beijing 100191 (China); Maenaka Human-Sensing Fusion project, Japan Science and Technology Agency, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Fujita, Takayuki [Maenaka Human-Sensing Fusion project, Japan Science and Technology Agency, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Uehara, Minoru [NEOMAX Co. Ltd., 2-15-17, Egawa, Shimamoto-Cho, Mishima-gun, Osaka 618-0013 (Japan); Iga, Yuki [Maenaka Human-Sensing Fusion project, Japan Science and Technology Agency, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Hashimoto, Taichi [Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Hao, Xiuchun; Higuchi, Kohei [Maenaka Human-Sensing Fusion project, Japan Science and Technology Agency, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Maenaka, Kazusuke [Maenaka Human-Sensing Fusion project, Japan Science and Technology Agency, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan)

    2011-11-15

    The silicon molding technique is described for patterning of NdFeB/Ta multilayered magnetic films and NdFeB magnetic powder at the micron scale. Silicon trenches are seamlessly filled by 12-{mu}m-thick NdFeB/Ta multilayered magnetic films with a magnetic retentivity of 1.3 T. The topography image and magnetic field distribution image are measured using an atomic force microscope and a magnetic force microscope, respectively. Using a silicon molding technique complemented by a lift-off process, NdFeB magnetic powder is utilized to fabricate magnetic microstructures. Silicon trenches as narrow as 20 {mu}m are filled by a mixture of magnetic powder and wax powder. The B-H hysteresis loop of the patterned magnetic powder is characterized using a vibrating sample magnetometer, which shows a magnetic retentivity of approximately 0.37 T. - Highlights: > We demonstrate the fabrication of micro-magnets using silicon molding processes. > NdFeB/Ta films are well filled in silicon trenches with a thickness of 12 {mu}m. > The 12-{mu}m-thick NdFeB/Ta magnetic film shows a retentivity of 1.3 T. > Magnetic structures as narrow as 20 {mu}m are fabricated using NdFeB magnetic powder. > VSM measurement shows a retentivity of 0.37 T for patterned NdFeB magnetic powder.

  17. Crystallization of the amorphous Fe{sub 80}Zr{sub 12}B{sub 8} alloy under controlled heating

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H. [School of Engineering (H6), University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Shao, G. [Centre for Materials Research and Innovation, University of Bolton, Bolton BL3 5AB (United Kingdom)], E-mail: G.Shao@bolton.ac.uk; Tsakiropoulos, P. [Department of Engineering Materials, Sir Robert Hadfirld Building, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2008-07-14

    The devitrification process of amorphous Fe{sub 80}Zr{sub 12}B{sub 8} alloy ribbons were studied under controlled thermal conditions. The major crystallization event during continuous heating with differential scanning calorimetory (DSC) is dictated by diffusion controlled growth and the associated atom mobility of the slow diffusing species Zr. The existence of prior nano-crystals formed by pre-annealing below the crystallization temperature had little effect on the major crystallization temperature. The crystallization sequence during heating was: amorphous {yields} amorphous + {alpha}-Fe + Fe{sub 3}Zr(B) {yields} amorphous + {alpha}-Fe + Fe{sub 3}Zr(B) + Fe{sub 2}Zr. Different from previous findings in alloys of lower Zr and B contents, the peak for the crystallization of the {alpha}-Fe phase alone is missing in the DSC traces of this alloy.

  18. Orientation and magnetic properties of the thick multilayered [NdFeBxTby]n films

    International Nuclear Information System (INIS)

    Liu, Weifang; Suzuki, Shunji; Machida, Kenichi

    2007-01-01

    Multilayered [NdFeB x /Tb y ] n films were prepared by a three-demensional sputtering system. From the thickness of NdFeB layer dependence on the orientation and magnetic properties of multilayered [NdFeB (xμm)/Tb (50nm)] n films with 7.2μm as a total thickness of NdFeB layers, it was found that the orientation of NdFeB grains was maintained. However, the coercivity was enhanced with decreasing the thickness of each NdFeB thin layer. The (BH) max value of 240kJ/m 3 was obtained on the layered [NdFeB (1.2μm)/Tb (50 nm)] 6 film as an optimal value. For the multilayered [NdFeB (1.2μm)/Tb (50 nm)] n films with various multiple layer sets (n), the coercivity value increased with the film thickness without any deterioration of the c-axis texture and consequently, multilayered NdFeB/Tb film magnets with total thickness values around 70μm showed the superior magnetic properties (H cj approx. = 1360kA/m, I r approx.= 1.05T, and (BH) max approx.= 202kJ/m 3 ). (author)

  19. Magnetization process in FePd thin films

    International Nuclear Information System (INIS)

    Klein, O.; Samson, Y.; Marty, A.; Guillous, S.; Viret, M.; Fermon, C.; Alloul, H.

    2001-01-01

    A custom made magnetic force microscope is used to study the magnetization process in thin films of FePd throughout the entire hysteresis loop. The 40 nm thick sample has a strong perpendicular anisotropy, which leads to a maze of 80 nm wide stripes of opposite polarity in the remanent state. The growth of M, when H increases, happens through an unwinding of the reversed domain along their axis. Together with the length recession, the reversed domain width also contracts with increasing field. The later effect is estimated by comparison of our images with magneto-optical Kerr measurements. A large disorder in the propagation process of the domain walls is observed. It is also found that the bubble configuration near the saturation field is unstable. [copyright] 2001 American Institute of Physics

  20. Thermomagnetically written domains in TbFeCo thin films

    International Nuclear Information System (INIS)

    Reim, W.; Weller, D.

    1988-01-01

    Characteristic features of thermomagnetically written domains in amorphous Tb x (Fe 90 Co 10 ) 100-x alloy thin films having different magnetic properties are reported. In particular, the writing process in materials with low Tb content chi ≤ 21 dominated by the demagnetizing field is compared to the bias field dominated process in Tb rich samples 22 ≤ chi ≤ 25. Domain wall movement over lateral dimensions of the bit size is found for Tb poor materials while for chi ≥ 22 domain boundaries are primarily determined by the area heated up to the Curie-temperature. The importance of mechanical stress on domain formation and irreversible changes of the storage medium due to overheating in the writing process are reported

  1. A novel selenization technique for fabrication of superconducting FeSex thin film

    International Nuclear Information System (INIS)

    Chai Qinglin; Tu Hailing; Hua Zhiqiang; Wang Lei; Qu Fei

    2011-01-01

    A novel selenization technique was applied to prepare superconducting FeSe x films with pre-set FeS films. The combination of reactive sputtering deposition with elemental diffusion technique would extend to prepare films of other iron-based superconductors. The results of transport measurement got close or greater than that of previous reports. T c,onset and T c,0 got to 10.2 K and 4 K respectively. We believe that increase of the content of Fe 7 Se 8 could not only reduce T c but also slow down the decline of resistivity. A combinative method with reactive sputtering deposition and selenization technique was applied to prepare superconducting FeSe x films on LaAlO 3 substrates successfully. The influence of selenizing temperature on film components was studied. FeSe 0.96 and FeSe films had similar and good performances in transport measurement but little difference in magnetic property. The critical onset temperature got to 11.2 K and T c,0 got to 4 K approximately. X-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy were used to analyze the ratio of constituents and morphology of several selenized films. FeSe x film had a porous structure on surface and no well preferred orientation, which were confirmed to have little influence on superconducting properties.

  2. Crystallization processes in an amorphous Co-Fe-Cr-Si-B alloy under isothermal annealing

    Science.gov (United States)

    Fedorets, A. N.; Pustovalov, E. V.; Plotnikov, V. S.; Modin, E. B.; Kraynova, G. S.; Frolov, A. M.; Tkachev, V. V.; Tsesarskaya, A. K.

    2017-09-01

    Research present the crystallization processes investigation of the amorphous Co67Fe3Cr3Si15B12 alloy. In-situ experiments on heating in a transmission electron microscope (TEM) column were carried out. Critical temperatures influencing material structure are determined. The onset temperature of material crystallization was determined.

  3. Crystallization of amorphous pseudobinary alloys of the type (Fe1-x Nix)80 B20

    International Nuclear Information System (INIS)

    Vasconcellos, M.A.Z.; Baibich, M.N.

    1984-01-01

    It was studied the crystallization of amorphous metallic ribbons of Fe 1-x Ni x 80 B 2 0 using the method of isochronous heating at variable slopes. The crystallization temperatures were determined from the transition observed in the electrical resistivity. (M.W.O.) [pt

  4. Shape of growing crystals of primary phases in autectic alloys of Fe - Fe2B and Ni - Ni3B systems

    International Nuclear Information System (INIS)

    Tavadze, F.N.; Garibashvili, V.I.; Nakaidze, Sh.G.

    1983-01-01

    Shapes of Fe 2 B and Ni 3 B crystal growth in eutectic Fe-B and Ni-B system alloys are considered. Iron hemiboride primary crystals take the form of a plane-face phase boundary and inherit a tetragonal prismatic lattice. After the crystal attains the critical size the dendritic branching occurs resulting in formation of a typical sceleton dendrite. Comparison of data obtained with entropy of melting for Fe 2 B and Ni 3 B borides shows that FeB crystals during the growth should take the spherical form. It is stated that the shape of growing crystals in Fe-Fe 2 B and Ni-Ni 2 B eutectic colonies is determined by the shape of borides

  5. Chemically fabricated LiFePO{sub 4} thin film electrode for transparent batteries and electrochromic devices

    Energy Technology Data Exchange (ETDEWEB)

    Béléké, Alexis B. [Institut de recherche d’Hydro-Québec, 1800 Boul. Lionel-Boulet, Varennes, QC J3X 1S3 (Canada); Department of Mining and Materials Engineering, McGill University, M.H. Wong Building, 3610 rue University, Montréal, QC H3A 2B2 (Canada); Faure, Cyril [Institut de recherche d’Hydro-Québec, 1800 Boul. Lionel-Boulet, Varennes, QC J3X 1S3 (Canada); Röder, Manuel [Center for Applied Electrochemistry, Fraunhofer Institute for Silicate Research, Neunerplatz 2, 97083 Würzburg (Germany); Hovington, Pierre [Institut de recherche d’Hydro-Québec, 1800 Boul. Lionel-Boulet, Varennes, QC J3X 1S3 (Canada); Posset, Uwe [Center for Applied Electrochemistry, Fraunhofer Institute for Silicate Research, Neunerplatz 2, 97083 Würzburg (Germany); Guerfi, Abdelbast [Institut de recherche d’Hydro-Québec, 1800 Boul. Lionel-Boulet, Varennes, QC J3X 1S3 (Canada); Zaghib, Karim, E-mail: zaghib.karim@ireq.ca [Institut de recherche d’Hydro-Québec, 1800 Boul. Lionel-Boulet, Varennes, QC J3X 1S3 (Canada)

    2016-12-15

    Graphical abstract: Simplified diagram of the novel sol-gel approach of preparation of colorless and transparent LiFePO{sub 4} thin film electrode. - Highlights: • Novel sol-gel synthesis of colorless LFP thin film electrode for transparent Li-ion battery. • High performance of the electrode at various current densities: 5, 10, 20, 50 and 100 μA/cm{sup 2}. • LFP nanoparticles exhibit an excellent electro-activity. • Colorless LFP thin film shows a transmittance above 80% versus FTO. • Higher transmittance of LFP electrode a potential candidate for electrochromic devices. - Abstract: We report a new sol-gel approach of synthesis of LiFePO{sub 4} (LFP) thin film and its application as cathode materials for transparent Li-ion battery in half-cell configuration. LFP thin films were obtained from an alcoholic colloidal suspension of iron acetylacetonate (Fe(AcAc){sub 3}) and aqueous lithium dihydrogen phosphate (LiH{sub 2}PO{sub 4}) deposited on fluorine tin oxide (FTO) glass substrate, followed by heating at 450 °C under nitrogen gas for 1 h. X-ray diffraction (XRD) confirmed that the LFP films have an orthorhombic crystal system with space group Pnma (62). Scanning electron microscopy (SEM) shows spherical LFP nanoparticles aggregates homogenously deposited all over the surface of FTO substrate containing 3-D open pores. The electrochemical behaviors of thin film vs Li/Li{sup +} cell were investigated by cyclic voltammetry and galvanostatic charge-discharge measurements. The cycle life was evaluated by running 1000 cycles of charge-discharge at a current density of 20 μA/cm{sup 2}. The transmission spectra reveal 85–90% of transparency versus FTO as reference, which makes it a potential candidate as a complementary electrode in electrochromic devices (ECDs).

  6. Correlation of magnetic and mechanical properties of hydrogenated, compositionally modulated, amorphous Fe80Zr20 films (abstract)

    International Nuclear Information System (INIS)

    Rengarajan, S.; Yun, E.J.; Lee, B.H.; Cho, B.I.; Walser, R.M.

    1996-01-01

    Recent research has demonstrated that large amounts of hydrogen can be electrolytically incorporated in amorphous, compositionally modulated (CM) FeZr films. The first irreversible changes in the magnetic state of an electrolytically hydrogenated iron-rich amorphous alloy were observed. The hydrogen-induced changes in the magnetization were interpreted in terms of specific structural rearrangements. In this work, simultaneous measurements of the variations in the magnetization and mechanical properties of these films were measured as a function of hydrogen charging to further clarify the hydrogen-induced structure changes. The Young close-quote s moduli E and internal friction d of as-deposited, and as-hydrogenated CM Fe 80 Zr 20 thin films were calculated from the displacements of a vibrating composite cantilever, measured using a laser heterodyne interferometer (LHI) having a displacement sensitivity of ∼0.01 A. E and d were measured using the resonant frequency method. CM films with thickness 1390 A and modulation wavelength ∼10 A were deposited on glass cantilevers (5 mm long, 2 mm wide, and 150 μm thick) by sequentially sputtering (rf diode) elemental Fe and Zr targets. The samples were electrolytically hydrogenated for various times in 2 N phosphoric acid with a current density of 26.3 mA/cm 2 . The maximum change in magnetization of the film (from 71.5 to 551 emu/cm 3 ) was observed after 5 min. During this time, E increased 18-fold from 535 GPa to 9.63 TPa. The unusually high Young close-quote s modulus of the as-deposited CM film is comparable to those previously observed in other CM films. The change is three times larger than the change in the E of carbon steel at the martensitic transformation, and nine times larger than the hydrogen induced increase in E of pure single crystals of iron. (Abstract Truncated)

  7. Crystal-fields at rare-earth sites in R2Fe14B compounds

    International Nuclear Information System (INIS)

    Adam, S.; Adam, G.; Burzo, E.

    1985-12-01

    Crystal-field effects are expected to be important in R 2 Fe 14 B compounds. Within a model-independent approach, it is proved that four distinct rare-earth sites exist with respect to the crystalline electric fields, namely, R(4f; z=0), R(4f; z=0.5 c), R(4g; z=0), and R(4g; z=0.5 c), and relationships are established between the corresponding crystal-fields coefficients. Further, generalized Stevens parametrizations of the crystal field coefficients are derived at three levels of approximation for the interatomic forces inside the crystal. A crystal lattice dressing effect upon the radial electronic integrals is found to occur, the magnitude of which depends on the deviation of the interatomic forces from Coulombian. Finally, computation of crystal-field coefficients in Nd 2 Fe 14 B leads to results which raise questions about the validity of the simple Coulomb point-charge model. (author)

  8. Enhancement of L10 ordering with the c-axis perpendicular to the substrate in FePt alloy film by using an epitaxial cap-layer

    Directory of Open Access Journals (Sweden)

    Mitsuru Ohtake

    2017-05-01

    Full Text Available FePt alloy thin films with cap-layers of MgO or C are prepared on MgO(001 single-crystal substrates by using a two-step method consisting of low-temperature deposition at 200 °C followed by high-temperature annealing at 600 °C. The FePt film thickness is fixed at 10 nm, whereas the cap-layer thickness is varied from 1 to 10 nm. The influences of cap-layer material and cap-layer thickness on the variant structure and the L10 ordering are investigated. Single-crystal FePt(001 films with disordered fcc structure (A1 grow epitaxially on the substrates at 200 °C. Single-crystal MgO(001 cap-layers grow epitaxially on the FePt films, whereas the structure of C cap-layers is amorphous. The phase transformation from A1 to L10 occurs when the films are annealed at 600 °C. The FePt films with MgO cap-layers thicker than 2 nm consist of L10(001 variant with the c-axis perpendicular to the substrate surface, whereas those with C cap-layers involve small volumes of L10(100 and (010 variants with the c-axis lying in the film plane. The in-plane and the out-of-plane lattices are respectively more expanded and contracted in the continuous-lattice MgO/FePt/MgO structure due to accommodations of misfits of FePt film with respect to not only the MgO substrate but also the MgO cap-layer. The lattice deformation promotes phase transformation along the perpendicular direction and L10 ordering. The FePt films consisting of only L10(001 variant show strong perpendicular magnetic anisotropies and low in-plane coercivities. The present study shows that an introduction of epitaxial cap-layer is effective in controlling the c-axis perpendicular to the substrate surface.

  9. Crystal structure and Mössbauer studies of the isotypic Fe6-cluster compounds RE15[Fe8C25], RE=Dy, Ho

    KAUST Repository

    Davaasuren, Bambar

    2015-05-01

    The carboferrates RE15[Fe8C25] (RE=Dy, Ho) were prepared from mixtures of the elements by arc-melting followed with subsequent annealing at 1373 K. The crystal structures were determined from single crystal X-ray diffraction data and revealed an isotypic relationship to Er15[Fe8C25] (hP48, P321). The main feature of the crystal structure is given by Fe6 cluster units characterized by covalent Fe-Fe bonding interactions. 57Fe Mössbauer spectra of Dy15[Fe8C25] were fitted by three subspectra with relative spectral weights of about 3:3:2 which is in general agreement with the crystal structure. Below 50 K, an onset of magnetic hyperfine fields at the three iron sites is observed which is supposed to be caused by dipolar fields arising from neighboring, slowly relaxing Dy magnetic moments.

  10. Analysis of NdFeB thin films prepared by facing target sputtering

    International Nuclear Information System (INIS)

    Shivalingappa, L.; Mohan, S.; Ghantasala, M.K.; Sood, D.K.

    1999-01-01

    In this paper, we present the details of our work on the deposition and characterization of NdFeB thin films. These films were prepared using facing target sputtering technique. The silicon(100) substrates were maintained at a substrate temperature of 400 to 600 deg C during deposition. Film structure, composition and magnetic properties are analyzed using Rutherford Backscattering Spectroscopy (RBS) and X-ray Diffraction (XRD) techniques. Films deposited below 400 deg C were x-ray amorphous, while the onset of crystallinity was observed with the films deposited at 500 deg C. Typical film composition was Nd:Fe:B = 2.2:12.5:2. Film composition appear to be a function of deposition conditions. Oxygen has been found to be the main impurity in the films. Oxygen content in the film reduced as the substrate temperature is increased

  11. Temperature dependence of the resistivity and tunneling magnetoresistance of sputtered FeHf(Si)O cermet films

    NARCIS (Netherlands)

    Strijkers, G.J.; Swagten, H.J.M.; Rulkens, B.; Bitter, R.H.J.N.; Jonge, de W.J.M.; Bloemen, P.J.H.; Schep, K.M.

    1998-01-01

    We have studied the tunneling resistivity and magnetoresistance of reactive sputter deposited FeHfO and FeHfSiO thin granular films. Maximum magnetoresistance ratios at room temperature of 2% and 3.2% were observed for films with compositions of Fe47Hf10O43 and Fe40Hf6Si6O48, respectively. The

  12. Effect of carbon additive on microstructure evolution and magnetic properties of epitaxial FePt (001) thin films

    International Nuclear Information System (INIS)

    Ding, Y.F.; Chen, J.S.; Liu, E.; Lim, B.C.; Hu, J.F.; Liu, B.

    2009-01-01

    FePt:C thin films were deposited on CrRu underlayers by DC magnetron co-sputtering. The effects of C content, FePt:C film thickness and substrate temperature on the microstructural and magnetic properties of the epitaxial FePt (001) films were studied. Experimental results showed that even with 30 vol.% C doping, the FePt films could keep a (001) preferred orientation at 350 deg. C . When a FePt:C film was very thin (< 5 nm), the film had a continuous microstructure instead of a granual structure with C diffused onto the film surface. With further increased film thickness, the film started to nucleate and formed a column microstructure over continuous FePt films. A strong exchange coupling in the FePt:C films was believed to be due to the presence of a thin continuous FePt layer attributed to the carbon diffusion during the initial stage of the FePt:C film growth. Despite the presence of a strong exchange coupling in the FePt:C (20 vol.% C) film, the SNR ratio of the FePt:C media was about 10 dB better than that of the pure FePt media. The epitaxial growth of the FePt:C films on the Pt layers was observed from high resolution TEM cross sectional images even for the films grown at about 200 deg. C . The TEM images did not show an obvious change in the morphology of the FePt:C films deposited at different temperatures (from 200 deg. C to 350 deg. C ), though the ordering degree and coercivity of the films increased with increased substrate temperature

  13. Carrier mobility and crystal perfection of tetracene thin film FET

    International Nuclear Information System (INIS)

    Moriguchi, N.; Nishikawa, T.; Anezaki, T.; Unno, A.; Tachibana, M.; Kojima, K.

    2006-01-01

    It is well-known that the carrier mobility of an organic field effect semiconductor (FET) depended on the crystal quality and/or the crystal perfection of the organic thin films [T.W. Kelly, D.V. Muyres, P.F. Baude, T.P. Smith, T.D. Jones, Mater. Res. Soc. Symp. Proc. 771 (2003) L6.5.1; D.J. Gundlach, J.A. Nichols, L. Zhou, T.N. Jackson, Appl. Phys. Lett. 80 (2002) 2925; H.K. Lauk, M. Halik, U. Zschieschang, G. Schmid, W. Radlik, J. Appl. Phys. 92 (2002) 5259; M. Shtein, J. Mapel, J.B. Benziger, S.R. Forrest, Appl. Phys. Lett. 81 (2002) 268; D. Knipp, R.A. Street, A.R. Volkel, Appl. Phys. Lett. 82 (2003) 3907; R. Ruiz, A.C. Mayer, G.G. Malliaras, Appl. Phys. Lett. 85 (2004) 4926; R.W.I. de Boer, M.E. Gershenson, A.F. Morpurgo, V. Podzorov, Phys. Stat. Sol. A 201 (2004) 1031]. To improve the crystal quality of the thin film many efforts were made. One of the important improvements was the surface treatment of the substrate. The tetracene thin film FET (top contact structure) was fabricated using the substrate, which was coated by a spin-coating method with a 0.1% poly α-methylstyrene (AMS) solution. The crystal quality was improved by this treatment so that the carrier mobility was higher than that of non-treatment. The maximum mobility of the AMS-treated sample was obtained to be 0.12 cm 2 /V s

  14. Crystal structures of sol-gel deposited zirconia thin films

    International Nuclear Information System (INIS)

    Bell, J.M.; Cheary, R.W.; Rice, M.; Ben-Nissan, B.; Cocking, J.L.; Johnstone, G.R.

    1992-01-01

    The authors reports on the crystal structure of zirconia thin films by high temperature x-ray diffraction. The films were deposited by sol-gel processing onto polished stainless steel substrates, and dried at 200 deg C. X-ray diffraction at temperatures between 400 deg C and 800 deg C was carried out using an APEX diffractometer with a position sensitive detector. Previous results indicated that there was a transformation between the tetragonal phase and the monoclinic phase at approximately 770 deg C. Two experiments have been carried out: temperature runs, where the structure evolution is studied as a function of temperature; and time evolution of the structure at fixed temperatures. The results for both experiments, including structural analysis of the different phases found in the thin zirconia films and an analysis of the kinetics of the phase transformation(s) from the time evolution work are presented. This will include a comparison with theories of nucleation and crystallisation in single element films. Impurity phases introduced by interaction of the zirconia with the substrate have been observed, and the effect of increasing annealing time on the substrate-film interaction will also be discussed. 17 refs., 1 tab., 3 figs

  15. Studies on electrodeposited Cd1-xFe xS thin films

    International Nuclear Information System (INIS)

    Deshmukh, S.K.; Kokate, A.V.; Sathe, D.J.

    2005-01-01

    Thin films of Cd 1-x Fe x S have been prepared on stainless steel and fluorine doped tin oxide (FTO) coated glass substrates using electrodeposition technique. Double distilled water containing precursors of Cd, Fe and S are used with ethylene diamine tetra-acetic acid (EDTA) disodium salt as a complexing agent to obtain good quality deposits by controlling the rate of reactions. The different preparative parameters like concentration of bath, deposition time, pH of the bath and Fe content in the bath have been optimized by photoelectrochemical (PEC) technique in order to get good quality thin films. Different techniques have been used to characterize electrodeposited Cd 1-x Fe x S thin films. The X-ray diffraction (XRD) analysis reveals that the films Cd 1-x Fe x S are polycrystalline in nature with crystallite size 282 A for the films deposited with optimized preparative parameters. Scanning electron microscopy (SEM) study for the sample deposited at optimized preparative parameters reveals that all grains uniformly distributed over the surface of stainless steel substrate indicates well defined growth of polycrystalline Cd-Fe-S material. Optical absorption shows the presence of direct transition and band gap energy decreases from 2.43 to 0.81 eV with the increase of Fe content from 0 to 1. PEC study shows the films of Cd 1-x Fe x S with x = 0.2 are more photosensitive than other compositions

  16. Nonlinear optical and electroabsorption spectra of polydiacetylene crystals and films

    Science.gov (United States)

    Mukhopadhyay, D.; Soos, Z. G.

    1996-01-01

    Vibronic structure of nonlinear optical (NLO) coefficients is developed within the Condon approximation, displaced harmonic oscillators, and crude adiabatic states. The displacements of backbone modes of conjugated polymers are taken from vibrational data on the ground and 1B excited state. NLO resonances are modeled by three excitations and transition moments taken from Pariser-Parr-Pople (PPP) theory and optimized to polydiacetylene (PDA) spectra in crystals and films, with blue-shifted 1B exciton. The joint analysis of third-harmonic-generation, two-photon absorption, and nondegenerate four-wave-mixing spectra of PDA crystals and films shows weak two-photon absorption to 2A below 1B, leading to overlapping resonances in the THG spectrum, strong two-photon absorption to an nA state some 35% above 1B, and weak Raman resonances in nondegenerate FWM spectra. The full π-π* spectrum contributes to Stark shifts and field-induced transitions, as shown by PPP results for PDA oligomers. The Stark shift dominates high-resolution electroabsorption (EA) spectra of PDA crystals below 10 K. The close correspondence between EA and the first-derivative I'(ω) of the linear absorption above the 1B exciton in PDA crystals provides an experimental separation of vibrational and electronic contributions that limits any even-parity state in this 0.5 eV interval. An oscillator-strength sum rule is applied to the convergence of PDA oligomers with increasing length, N, and the crystal oscillator strengths are obtained without adjustable parameters. The sum rule for the 1B exciton implies large transition moments to higher-energy Ag states, whose locations in recent models are contrasted to PPP results. Joint analysis of NLO and EA spectra clarifies when a few electronic excitations are sufficient, distinguishes between vibrational and electronic contributions, and supports similar π-electron interactions in conjugated molecules and polymers.

  17. Magnetic, structural and electrical properties of ordered and disordered Co50Fe50 films

    International Nuclear Information System (INIS)

    Chen, Y.T.; Jen, S.U.; Yao, Y.D.; Wu, J.M.; Hwang, G.H.; Tsai, T.L.; Chang, Y.C.; Sun, A.C.

    2006-01-01

    Co 50 Fe 50 films with thickness varying from 100 to 500 A were deposited on a glass substrate by sputtering process, respectively. Two kinds of CoFe films were studied: one was the as-deposited film, and the other the annealed film. The annealing procedure was to keep the films at 400 deg. C for 5 h in a vacuum of 5x10 -6 mbar. From the X-ray study, we find that the as-deposited film prefers the CoFe(1 1 0) orientation. Moreover, the body-centered cubic (bcc) CoFe(1 1 0) line is split into two peaks: one corresponding to the ordered body-centered tetragonal (bct) phase, and the other, the disordered bcc phase. After annealing, the peak intensity of the ordered bct phase becomes much stronger, while that of the disordered bcc phase disappears. The annealing has also caused the ordered CoFe(2 0 0) line to appear. When the amount of the ordered bct phase in Co 50 Fe 50 is increased, the saturation magnetization (M s ) and coercivity (H c ) become larger, but the electrical resistivity (ρ) decreases. From the temperature coefficient of resistance (TCR) measurement, we learn that the bct grains in the CoFe film start to grow at temperature 82 deg. C

  18. Room temperature ferromagnetism in Fe-doped semiconductor ZrS2 single crystals

    Science.gov (United States)

    Muhammad, Zahir; Lv, Haifeng; Wu, Chuanqiang; Habib, Muhammad; Rehman, Zia ur; Khan, Rashid; Chen, Shuangming; Wu, Xiaojun; Song, Li

    2018-04-01

    Two dimensional (2D) layered magnetic materials have obtained much attention due to their intriguing properties with a potential application in the field of spintronics. Herein, room-temperature ferromagnetism with 0.2 emu g‑1 magnetic moment is realized in Fe-doped ZrS2 single crystals of millimeter size, in comparison with diamagnetic behaviour in ZrS2. The electron paramagnetic resonance spectroscopy reveals that 5.2wt% Fe-doping ZrS2 crystal exhibit high spin value of g-factor about 3.57 at room temperature also confirmed this evidence, due to the unpaired electrons created by doped Fe atoms. First principle static electronic and magnetic calculations further confirm the increased stability of long range ferromagnetic ordering and enhanced magnetic moment in Fe-doped ZrS2, originating from the Fe spin polarized electron near the Fermi level.

  19. Laser direct-write and crystallization of FeSi II micro-dot array for NIR light-emitting device application

    Science.gov (United States)

    Narazaki, Aiko; Kurosaki, Ryozo; Sato, Tadatake; Kawaguchi, Yoshizo; Niino, Hiroyuki

    2007-02-01

    We printed FeSi II micro-dot array on various kinds of substrates utilizing laser-induced forward transfer (LIFT). An amorphous FeSi II was deposited by sputtering on a transparent plate as a source film. A single KrF excimer laser pulse through a mask-projection system was imaged with a small micrometer-sized grid pattern onto a film/plate interface, resulting in the deposition of FeSi II micro-dot array on a facing substrate with a high number density of 10 4 mm -2. FeSi II in the β crystalline phase is a promising eco-friendly semiconductor because of NIR electroluminescence used for optical networking as well as abundant components reserve on the earth and non-toxicity. However, the β-FeSi II film fabrication generally required high-temperature multi-processes which hamper its integration and performance reproducibility. Using the LIFT of micro-dot array, we succeeded in room-temperature preparation of β-FeSi II. Micro-Raman spectroscopy confirmed the β crystalline phase in the micro-dots deposited on an unheated silica glass substrate. Thus, the LIFT is useful for integrating functional micro-dot array accompanied by the crystallization at lower temperatures.

  20. Optical and magneto-optical characterization of TbFeCo thin films in trilayer structures

    International Nuclear Information System (INIS)

    McGahan, W.A.; He, P.; Chen, L.; Bonafede, S.; Woollam, J.A.; Sequeda, F.; McDaniel, T.; Do, H.

    1991-01-01

    A series of TbFeCo films ranging in thickness from 100 to 800 A have been deposited in trilayer structures on silicon wafer substrates, with Si 3 N 4 being employed as the dielectric material. These films have been characterized both optically and magneto-optically by variable angle of incidence spectroscopic ellipsometry, normal angle of incidence reflectometry, and normal angle of incidence Kerr spectroscopy. From these measurements, the optical constants n and k have been determined for the TbFeCo films, as well as the magneto-optical constants Q1 and Q2. Results are presented that demonstrate the lack of dependence of these constants on the thickness of the TbFeCo film, and which can be used for calculating the expected optical and magneto-optical response of any multilayer structure containing similar TbFeCo films

  1. Thin film pc-Si by aluminium induced crystallization on metallic substrate

    Directory of Open Access Journals (Sweden)

    Cayron C.

    2013-04-01

    Full Text Available Thin film polycrystalline silicon (pc-Si on flexible metallic substrates is promising for low cost production of photovoltaic solar cells. One of the attractive methods to produce pc-Si solar cells consists in thickening a large-grained seed layer by epitaxy. In this work, the deposited seed layer is made by aluminium induced crystallization (AIC of an amorphous silicon (a-Si thin film on metallic substrates (Ni/Fe alloy initially coated with a tantalum nitride (TaN conductive diffusion barrier layer. Effect of the thermal budget on the AIC grown pc-Si seed layer was investigated in order to optimize the process (i.e. the quality of the pc-Si thin film. Structural and optical characterizations were carried out using optical microscopy, μ-Raman and Electron Backscatter Diffraction (EBSD. At optimal thermal annealing conditions, the continuous AIC grown pc-Si thin film showed an average grain size around 15 μm. The grains were preferably (001 oriented which is favorable for its epitaxial thickening. This work proves the feasibility of the AIC method to grow large grains pc-Si seed layer on TaN coated metal substrates. These results are, in terms of grains size, the finest obtained by AIC on metallic substrates.

  2. Investigation of Fe-Si-N films as magnetic overcoat for high density recording disk drives

    International Nuclear Information System (INIS)

    Gauvin, M.; Talke, F. E.; Fullerton, E. E.

    2010-01-01

    A 50-nm-thick Fe-Si-N films were deposited via reactive magnetron cosputtering of independent Fe and Si targets, in Ar/N 2 gas mixture, under different dc Fe target power conditions. Magnetic properties, mechanical hardness and tribological properties were characterized as a function of the Fe target power by magnetometry, nanoindentation, and nanoscratch testing, respectively. Deposited samples were found to be ferromagnetic with a coercivity of approximately 20 Oe and a saturation magnetization increasing from 200 to 1100 emu/cm 3 as a function of Fe sputter power, i.e., values typical of soft magnetic materials. The mechanical hardness was found to be between 50% and 70% of the hardness of a pure SiN x film. Nanotribological properties of films deposited with a Fe target power ≥80 W degraded rapidly.

  3. Magnetic x-ray linear dichroism of ultrathin Fe-Ni alloy films

    Energy Technology Data Exchange (ETDEWEB)

    Schumann, F.O.; Willis, R.F. [Pennsylvania State Univ., University Park, PA (United States); Goodman, K.W. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    The authors have studied the magnetic structure of ultrathin Fe-Ni alloy films as a function of Fe concentration by measuring the linear dichroism of the 3p-core levels in angle-resolved photoemission spectroscopy. The alloy films, grown by molecular-beam epitaxy on Cu(001) surfaces, were fcc and approximately four monolayers thick. The intensity of the Fe dichroism varied with Fe concentration, with larger dichroisms at lower Fe concentrations. The implication of these results to an ultrathin film analogue of the bulk Invar effect in Fe-Ni alloys will be discussed. These measurements were performed at the Spectromicroscopy Facility (Beamline 7.0.1) of the Advanced Light Source.

  4. Magnetic properties and microstructure of low ordering temperature L10 FePt thin films

    International Nuclear Information System (INIS)

    Sun, A.C.; Kuo, P.C.; Chen, S.C.; Chou, C.Y.; Huang, H.L.; Hsu, J.H.

    2004-01-01

    Polycrystalline Fe 52 Pt 48 alloy thin films were prepared by dc magnetron sputtering on preheated natural-oxidized silicon wafer substrates. The film thickness was varied from 10 to 100 nm. The as-deposited film was encapsulated in a quartz tube and postannealed in vacuum at various temperatures for 1 h, then furnace cooled. It is found that the ordering temperature from as-deposited soft magnetic fcc FePt phase to hard magnetic fct L1 0 FePt phase could be reduced to about 350 deg. C by preheating substrate and furnace cooling treatment. The magnetic properties measurements indicated that the in-plane coercivity of the films was increased rapidly as annealing temperature is increased from 300 to 400 deg. C, but it decreased when the annealing temperature is higher than 400 deg. C. X-ray diffraction analysis shown that the as-deposited FePt thin film was a disorder fcc FePt phase. The magnetic measurement indicated that the transformation of disorder fcc FePt to fct L1 0 FePt phase was started at about 350 deg. C, which is consistent with the analysis of x-ray diffraction patterns. From scanning electron microscopy observation and selected area energy disperse spectrum analysis, the distributions of Fe and Pt elements in the films became nonuniform when the annealing temperature was higher than 500 deg. C due to the formation of the Fe 3 Pt phase. After annealing at 400 deg. C, the in plane coercivity of Fe 52 Pt 48 thin film with film thickness of 100 nm is 10 kOe, M s is 580 emu/cm3, and grain size is about 12 nm

  5. Kinetics and Mechanisms of Oxygen Surface Exchange on La0.6Sr0.4FeO3-delta Thin Films

    OpenAIRE

    Mosleh, Majid; Søgaard, Martin; Hendriksen, Peter Vang

    2009-01-01

    The thermodynamic properties as well as oxygen exchange kinetics were examined on mixed ionic and electronic conducting (La0.6Sr0.4)0.99FeO3− (LSF64) thin films deposited on MgO single crystals. It is found that thin films and bulk material have the same oxygen stoichiometry for a given temperature and oxygen partial pressure [i.e., the incorporation reaction has the same reaction enthalpy (H0=−105 KJ/mol) and entropy (S0=−75.5 J/mol/K) as found for bulk material]. The thin film shows smaller...

  6. Effect of anisotropy on anomalous Hall effect in Tb-Fe thin films

    International Nuclear Information System (INIS)

    Babu, V. Hari; Markandeyulu, G.; Subrahmanyam, A.

    2009-01-01

    The electrical and Hall resistivities of Tb x Fe 100-x thin films in the temperature range 13-300 K were investigated. The sign of Hall resistivity at 300 K is found to change from positive for x=28 film to negative for x=30 film, in accordance with the compensation of Tb and Fe moments. All the films are seen to have planar magnetic anisotropy at 13 K. The temperature coefficients of electrical resistivities of the amorphous films with 19≤x≤51 are seen to be negative. The temperature dependence of Hall resistivity of these films is explained on the basis of random magnetic anisotropy model. The temperature dependences of Hall resistivities of the x=22 and 41 films are seen to exhibit a nonmonotonous behavior due to change in anisotropy from perpendicular to planar. The same behavior is considered for the explanation regarding the probable formation of Berry phase curvature in these films.

  7. Nanolaminated FeCoB/FeCo and FeCoB/NiFe soft magnetic thin films with tailored magnetic properties deposited by magnetron sputtering

    Science.gov (United States)

    Hida, Rachid; Falub, Claudiu V.; Perraudeau, Sandrine; Morin, Christine; Favier, Sylvie; Mazel, Yann; Saghi, Zineb; Michel, Jean-Philippe

    2018-05-01

    Thin films based on layers of Fe52Co28B20 (at%), Fe65Co35 (at%), and Ni80Fe20 (at%) were deposited by sputtering on 8″ bare Si and Si/200 nm-thermal-SiO2 wafers by simultaneous use of two or more cathodes. Due to the continuous rotation of the substrate cage, such that the substrates faced different targets alternately, the multilayers consisted of stacks of alternating, nanometer-thick regular layers. The composition of the films was determined by Rutherford Backscattering Spectrometry (RBS) and Nuclear Reactive Analysis (NRA), whereas Plasma Profiling Time of Flight Mass Spectrometry (PP-TOFMS) analysis gave depth profile information about the chemical elements. The structural and magnetic properties of the films were investigated by X-ray Diffraction and by TEM analysis, B-H loop tracer and high frequency single coil technique permeametry, respectively. The linear dependence of the coercivity of these thin films versus the grain size can be explained by the random anisotropy model. These novel, composite soft magnetic multilayers, with tunable in-plane anisotropy, allow operation at tunable frequencies, as shown by broadband (between 100 MHz and 10 GHz) RF measurements that exhibit a classical Landau-Lifschitz-Gilbert (LLG) behavior and, combine the magnetic properties of the individual materials in an advantageous way. This article presents a method to produce nanostructured soft magnetic multilayers, the properties of which can easily be tuned by choosing the ratio of the individual nanolayers. In this way it's possible to combine soft magnetic materials with complementary properties, e.g. high saturation magnetization, low coercivity, high specific resistivity and low magnetostriction

  8. Effect of Ti seed and spacer layers on structure and magnetic properties of FeNi thin films and FeNi-based multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Svalov, A.V., E-mail: andrey.svalov@ehu.es [Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain); Department of Magnetism and Magnetic Nanomaterials, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Larrañaga, A. [SGIker, Servicios Generales de Investigación, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain); Kurlyandskaya, G.V. [Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain); Department of Magnetism and Magnetic Nanomaterials, Ural Federal University, 620002 Ekaterinburg (Russian Federation)

    2014-10-15

    Highlights: • Fe{sub 19}Ni{sub 81} films and FeNi-based multilayers were prepared by magnetron sputtering. • The samples were deposited onto glass substrates at room temperature. • Ti/FeNi films exhibit good (1 1 1) texture and crystallinity. • The thick Cu seed increases the coercive force of the magnetic layer. • The thin Ti spacer restores the magnetic softness of the Cu/Ti/FeNi multilayers. - Abstract: The microstructure and magnetic properties of sputtered permalloy films and FeNi-based multilayers prepared by magnetron sputtering have been studied. X-ray diffraction measurements indicate that Ti/FeNi films exhibit good (1 1 1) texture and crystallinity. Ti/FeNi bilayers with high crystallographic quality have relatively low resistivity. The Ti seed layer does not influence the magnetic properties of FeNi film in Ti/FeNi bilayers, but the thick Cu seed layer leads to an increase of the coercive force of the magnetic layer. For the FeNi films deposited on thick Cu seed layer, the (0 1 0) and (0 0 2) diffraction peaks of hcp nickel were clearly observed. The thin Ti spacer between Cu and FeNi layers prevents the formation of the nickel phase and restores the magnetic softness of the FeNi layer in the Cu/Ti/FeNi sample. Obtained results can be important for the development of multilayer sensitive elements for giant magnetoimpedance or magnetoresistance detectors.

  9. Soft Magnetic Properties of High-Entropy Fe-Co-Ni-Cr-Al-Si Thin Films

    Directory of Open Access Journals (Sweden)

    Pei-Chung Lin

    2016-08-01

    Full Text Available Soft magnetic properties of Fe-Co-Ni-Al-Cr-Si thin films were studied. As-deposited Fe-Co-Ni-Al-Cr-Si nano-grained thin films showing no magnetic anisotropy were subjected to field-annealing at different temperatures to induce magnetic anisotropy. Optimized magnetic and electrical properties of Fe-Co-Ni-Al-Cr-Si films annealed at 200 °C are saturation magnetization 9.13 × 105 A/m, coercivity 79.6 A/m, out-of-plane uniaxial anisotropy field 1.59 × 103 A/m, and electrical resistivity 3.75 μΩ·m. Based on these excellent properties, we employed such films to fabricate magnetic thin film inductor. The performance of the high entropy alloy thin film inductors is superior to that of air core inductor.

  10. L1{sub 0} phase transition in FePt thin films via direct interface reaction

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiaohong; Sun Hongyu; Wang Fengqing; Li Wei; Zhang Xiangyi [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, 066004 Qinhuangdao (China); Liu Baoting; Guo Jianxin [College of Physics Science and Technology, Hebei University, 071002 Baoding (China)], E-mail: xyzh66@ysu.edu.cn

    2008-12-07

    Lowering the L1{sub 0} ordering temperature of FePt films is of great significance for their application as an ultrahigh density magnetic recording medium. In this study, the L1{sub 0} ordering process of FePt thin films deposited directly on Si substrates has been significantly accelerated by the interface reaction between the thin film and the Si substrate, and thus the thin films show a low L1{sub 0} ordering temperature of T = 310 deg. C as compared with those deposited on Si/SiO{sub 2} substrates. The accelerated L1{sub 0} ordering transition is predominantly dependent on the rapid growth of the ordered domains during the interface reaction. The film thickness has an important effect on the interface reaction and thus can be used to tune the L1{sub 0} ordering process of the FePt films.

  11. L10 phase transition in FePt thin films via direct interface reaction

    International Nuclear Information System (INIS)

    Li Xiaohong; Sun Hongyu; Wang Fengqing; Li Wei; Zhang Xiangyi; Liu Baoting; Guo Jianxin

    2008-01-01

    Lowering the L1 0 ordering temperature of FePt films is of great significance for their application as an ultrahigh density magnetic recording medium. In this study, the L1 0 ordering process of FePt thin films deposited directly on Si substrates has been significantly accelerated by the interface reaction between the thin film and the Si substrate, and thus the thin films show a low L1 0 ordering temperature of T = 310 deg. C as compared with those deposited on Si/SiO 2 substrates. The accelerated L1 0 ordering transition is predominantly dependent on the rapid growth of the ordered domains during the interface reaction. The film thickness has an important effect on the interface reaction and thus can be used to tune the L1 0 ordering process of the FePt films.

  12. Nitrided FeB amorphous thin films for magneto mechanical systems

    International Nuclear Information System (INIS)

    Fernandez-Martinez, I.; Martin-Gonzalez, M.S.; Gonzalez-Arrabal, R.; Alvarez-Sanchez, R.; Briones, F.; Costa-Kraemer, J.L.

    2008-01-01

    The structural, magnetic and magnetoelastic properties of Fe-B-N amorphous films, sputtered from a Fe 80 B 20 target, in a mixture of argon and nitrogen gas, are studied for different nitrogen partial pressures. Nitrogen incorporates into the film preserving the amorphous structure, and modifying magnetic properties. The amount of nitrogen that incorporates into the amorphous structure is found to scale linearly with the nitrogen partial pressure during film growth. The structure, magnetization, field evolution, magnetic anisotropy and magnetostrictive behaviour are determined for films with different nitrogen content. An ∼20% increase of both the saturation magnetization and the magnetostriction constant values is found for moderate (∼8%) nitrogen content when compared to those for pure Fe 80 B 20 amorphous films. These improved properties, together with the still low coercivity of the amorphous films offer great potential for their use in magnetostrictive micro and nano magneto mechanical actuator devices

  13. Nano size crystals of goethite, α-FeOOH: Synthesis and thermal transformation

    International Nuclear Information System (INIS)

    Christensen, Axel Norlund; Jensen, Torben R.; Bahl, Christian R.H.; DiMasi, Elaine

    2007-01-01

    An aqueous suspension of amorphous iron(III) hydroxide was kept at room temperature (298 K) for 23 years. During this period of time the pH of the liquid phase changed from 4.3 to 2.85, and nano size crystals of goethite, α-FeOOH crystallised from the amorphous iron(III) hydroxide. Transmission electron microscopy (TEM) investigations, Moessbauer spectra, and powder X-ray diffraction using Co Kα radiation showed that the only iron containing crystalline phase present in the recovered product was α-FeOOH. The size of these nano particles range from 10 to 100 nm measured by TEM. The thermal decomposition of α-FeOOH was investigated by time-resolved in situ synchrotron radiation powder X-ray diffraction and the data showed that the sample of α-FeOOH transformed to α-Fe 2 O 3 in the temperature range 444-584 K. A quantitative phase analysis shows the increase in scattered X-ray intensity from α-Fe 2 O 3 to follow the decrease of intensity from α-FeOOH in agreement with the topotactic phase transition. - Graphical abstract: Nano size crystals of goethite, α-FeOOH formed from amorphous iron(III) hydroxide after 23 years, and transforms faster to α-Fe 2 O 3 upon heating

  14. Ionic and electronic dark decay of holograms in LiNbO3:Fe crystals

    International Nuclear Information System (INIS)

    Yang, Yunping; Nee, Ingo; Buse, Karsten; Psaltis, Demetri

    2001-01-01

    The lifetimes of nonfixed holograms in LiNbO 3 :Fe crystals with doping levels of 0.05, 0.138, and 0.25 wt% Fe 2 O 3 have been measured in the temperature range from 30 to 180 degree C. The time constants of the dark decay of holograms stored in crystals with doping levels of 0.05 and 0.25 wt% Fe 2 O 3 obey an Arrhenius-type dependence on absolute temperature T, but yield two activation energies: 1.0 and 0.28 eV, respectively. For these crystals, two different dark decay mechanisms are prevailing, one of which is identified as proton compensation and the other is due to electron tunneling between sites of Fe 2+ and Fe 3+ . The dark decay of holograms stored in crystals with the doping level of 0.138 wt% Fe 2 O 3 is the result of a combination of both effects. [copyright] 2001 American Institute of Physics

  15. Application of Thin Films of Conjugated Polymers in Novel LED's and Liquid Crystal 'Light Valves'

    National Research Council Canada - National Science Library

    MacDiarmid, A

    1997-01-01

    .... Flexible, completely organic polymer dispersed liquid crystal light valves have been fabricated from transparent plastic substrates on which a conducting film of polypyrrole has been deposited...

  16. Synthesis and characterization of liquid crystals and their thermoset films

    International Nuclear Information System (INIS)

    Ahn, Yong-Ho; Jung, Myung-Sup; Chang, Jin-Hae

    2010-01-01

    We prepared a series of aromatic liquid crystals (LCs) based on aromatic ester units with the reactive end groups methyl-maleimide and nadimide, and the resulting LCs were thermally cross-linked to produce liquid crystalline thermoset (LCT) films by means of solution-casting and heat treatment. The synthesized LCs and LCTs were characterized with Fourier transform infrared (FT-IR) spectroscopy, 1 H nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and polarizing optical microscopy with a hot stage. We found that all these LCs form nematic phases. The coefficients of thermal expansion (CTEs) of the LCT films are strongly affected by the reactive end group and the mesogen units in their main-chain structures. The methyl-maleimide-terminated biphenyl LCT was found to have the lowest CTE.

  17. A study on lead myristate (LM) soap film crystal by positron annihilation life spectroscopy

    International Nuclear Information System (INIS)

    Shi Zikang; Yu xianchun

    1992-01-01

    The quality of the LM soap film crystal is determined by means of the positron annihilation life spectroscopy. It is found that the technology to be used to make soap film will influence the film quality and the film quality can be improved by a reasonable heat treatment

  18. Nano-impact testing of TiFeN and TiFeMoN films for dynamic toughness evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Beake, B D [Micro Materials Ltd, Willow House, Ellice Way, Yale Business Village, Wrexham LL13 7YL (United Kingdom); Vishnyakov, V M; Colligon, J S, E-mail: ben@micromaterials.co.uk [Dalton Research Institute, Manchester Metropolitan University, Manchester M1 5GD (United Kingdom)

    2011-03-02

    TiFeN and TiFeMoN films were deposited on silicon wafers by ion-beam-assisted deposition. Their mechanical properties were measured by nanoindentation (quasi-static) and nano-impact (dynamic) techniques. Nano-impact testing enabled assessment of their toughness and resistance to fatigue fracture under repetitive loading. At low impact forces, films with a higher resistance to plastic deformation (H{sup 3}/E{sup 2}) were much more resistant to the formation of cracks throughout the test. At higher impact forces, these films initially show impact resistance but with continued impacts they are unable to protect the Si substrate, performing as poorly as films with lower H{sup 3}/E{sup 2} and suffer delamination from the Si substrate over a large area.

  19. Magnetic properties and configuration of Fe{sub 50}Pt{sub 50*x}Rh{sub x} films

    Energy Technology Data Exchange (ETDEWEB)

    Fenske, Jochen; Lott, Dieter; Schreyer, Andreas [Helmholt-Zentrum, Geesthacht (Germany); Schmidt, Wolfgang; Schmalzl, Karin [IFF Forschungszentrum, Juelich (Germany); JCNS at ILL (France); Mankey, Gary J. [MINT Center, University of Alabama (United States); Klose, Frank [Ansto, Bragg Institute (Australia); Tartakowskaya, Helena [Institute for Magnetism, National Accademy of Scinece (Ukraine)

    2011-07-01

    Ordered FePt alloys with L1{sub 0} structure are known as materials with FM order and a high magnetic moment of Fe providing a large magnetization. The large atomic number of Pt on the other hand results in a high magnetic anisotropy. If grown in thin films, the high anisotropy often results in perpendicular magnetization which is the preferred orientation for current magnetic recording media. One way to control the magnetic properties in these materials is through the introduction of a third element into the crystal matrix e.g. Rh. When Rh is added to replace Pt in the equiatomic alloy, new magnetic phases emerge. Here we present neutron diffraction studies on the magnetic properties of different 200nm thick Fe{sub 50}Pt{sub 50*x}Rh{sub x} films in dependence of the temperature and external magnetic fields. Additional resonant x-ray measurements on the Fe and Pt absorption edges provide additional information about the magnetic moments on these sites.

  20. Investigation of the magnetic properties in thin Fe50Pt50-xRhx films by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Fenske, J.; Lott, D.; Schreyer, A. [GKSS Research Centre (Germany); Mankey, G.J. [University of Alabama, MINT Center (United States); Schmidt, W.; Schmalzl, K. [Juelich Research Centre (Germany); Tartakowskaya, E. [Institute for Magnetism, National Accademy of Science (United States)

    2009-07-01

    FePt-based alloys are typically the material of choice for magnetic information storage media. The high magnetic moment of Fe gives a large magnetization and the large atomic number of Pt results in a high magnetic anisotropy. This combination enables the written bits to be smaller than ever before, since magnetic grains with a high magnetic anisotropy are more thermally stable. One way to control the magnetic properties in these materials is through the introduction of a third element into the crystal matrix, e.g. Rh. When Rh is added to replace Pt in the equiatomic alloy, new magnetic phases emerge. Bulk samples of Fe{sub 50}Pt{sub 40}Rh{sub 10} for example, studied by magnetization measurements refer to an antiferromagnetic (AF)/ferromagnetic (FM) phase transition at about 150 K when heated. Additional magnetostriction measurements indicate that the phase transition could also be induced by applying a magnetic field. Here we present results on several Fe{sub 50}Pt{sub 50-x}Rh{sub x} films. These films were examined by neutron diffraction in dependence of temperature and magnetic field. The observed magnetic behaviours differ significant from the behaviour of the bulk system.

  1. Micro-patterning of NdFeB and SmCo magnet films for integration into micro-electro-mechanical-systems

    International Nuclear Information System (INIS)

    Walther, A.; Marcoux, C.; Desloges, B.; Grechishkin, R.; Givord, D.; Dempsey, N.M.

    2009-01-01

    The integration of high-performance RE-TM (NdFeB and SmCo) hard magnetic films into micro-electro-mechanical-systems (MEMS) requires their patterning at the micron scale. In this paper we report on the applicability of standard micro-fabrication steps (film deposition onto topographically patterned substrates, wet etching and planarization) to the patterning of 5-8 μm thick RE-TM films. While NdFeB comprehensively fills micron-scaled trenches in patterned substrates, SmCo deposits are characterized by poor filling of the trench corners, which poses a problem for further processing by planarization. The magnetic hysteresis loops of both the NdFeB and SmCo patterned films are comparable to those of non-patterned films prepared under the same deposition/annealing conditions. A micron-scaled multipole magnetic field pattern is directly produced by the unidirectional magnetization of the patterned films. NdFeB and SmCo show similar behavior when wet etched in an amorphous state: etch rates of approximately 1.25 μm/min and vertical side walls which may be attributed to a large lateral over-etch of typically 20 μm. Chemical-mechanical-planarization (CMP) produced material removal rates of 0.5-3 μm/min for amorphous NdFeB. Ar ion etching of such films followed by the deposition of a Ta layer prior to film crystallization prevented degradation in magnetic properties compared to non-patterned films

  2. Micro-patterning of NdFeB and SmCo magnet films for integration into micro-electro-mechanical-systems

    Energy Technology Data Exchange (ETDEWEB)

    Walther, A. [CEA Leti-MINATEC, 17 rue des Martyrs, 38054 Grenoble (France); Institut Neel, CNRS-UJF, 25 rue des Martyrs, 38042 Grenoble (France); Marcoux, C.; Desloges, B. [CEA Leti-MINATEC, 17 rue des Martyrs, 38054 Grenoble (France); Grechishkin, R. [Laboratory of Magnetoelectronics, Tver State University, 170000 Tver (Russian Federation); Givord, D. [Institut Neel, CNRS-UJF, 25 rue des Martyrs, 38042 Grenoble (France); Dempsey, N.M. [Institut Neel, CNRS-UJF, 25 rue des Martyrs, 38042 Grenoble (France)], E-mail: nora.dempsey@grenoble.cnrs.fr

    2009-03-15

    The integration of high-performance RE-TM (NdFeB and SmCo) hard magnetic films into micro-electro-mechanical-systems (MEMS) requires their patterning at the micron scale. In this paper we report on the applicability of standard micro-fabrication steps (film deposition onto topographically patterned substrates, wet etching and planarization) to the patterning of 5-8 {mu}m thick RE-TM films. While NdFeB comprehensively fills micron-scaled trenches in patterned substrates, SmCo deposits are characterized by poor filling of the trench corners, which poses a problem for further processing by planarization. The magnetic hysteresis loops of both the NdFeB and SmCo patterned films are comparable to those of non-patterned films prepared under the same deposition/annealing conditions. A micron-scaled multipole magnetic field pattern is directly produced by the unidirectional magnetization of the patterned films. NdFeB and SmCo show similar behavior when wet etched in an amorphous state: etch rates of approximately 1.25 {mu}m/min and vertical side walls which may be attributed to a large lateral over-etch of typically 20 {mu}m. Chemical-mechanical-planarization (CMP) produced material removal rates of 0.5-3 {mu}m/min for amorphous NdFeB. Ar ion etching of such films followed by the deposition of a Ta layer prior to film crystallization prevented degradation in magnetic properties compared to non-patterned films.

  3. Synthesis of nanocrystalline nickel-zinc ferrite (Ni0.8Zn0.2Fe2O4) thin films by chemical bath deposition method

    International Nuclear Information System (INIS)

    Pawar, D.K.; Pawar, S.M.; Patil, P.S.; Kolekar, S.S.

    2011-01-01

    Graphical abstract: Display Omitted Research highlights: → We have successfully synthesized nickel-zinc ferrite (Ni 0.8 Zn 0.2 Fe 2 O 4 ) thin films on stainless steel substrates using a low temperature chemical bath deposition method. → The surface morphological study showed the compact flakes like morphology. → The as-deposited thin films are hydrophilic (10 o o ) whereas the annealed thin films are super hydrophilic (θ o ) in nature. → Ni 0.8 Zn 0.2 Fe 2 O 4 thin films could be used in supercapacitor. - Abstract: The nickel-zinc ferrite (Ni 0.8 Zn 0.2 Fe 2 O 4 ) thin films have been successfully deposited on stainless steel substrates using a chemical bath deposition method from alkaline bath. The films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), static water contact angle and cyclic voltammetry measurements. The X-ray diffraction pattern shows that deposited Ni 0.8 Zn 0.2 Fe 2 O 4 thin films were oriented along (3 1 1) plane. The FTIR spectra showed strong absorption peaks around 600 cm -1 which are typical for cubic spinel crystal structure. SEM study revealed compact flakes like morphology having thickness ∼1.8 μm after air annealing. The annealed films were super hydrophilic in nature having a static water contact angle (θ) of 5 o .The electrochemical supercapacitor study of Ni 0.8 Zn 0.2 Fe 2 O 4 thin films has been carried out in 6 M KOH electrolyte. The values of interfacial and specific capacitances obtained were 0.0285 F cm -2 and 19 F g -1 , respectively.

  4. Formation and crystallization kinetics of Nd-Fe-B-based bulk amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qiong; Ge, Hongliang; Zhang, Pengyue; Li, Dongyun; Wang, Zisheng [China Jiliang University, Magnetism Key Laboratory of Zhejiang Province, Hangzhou (China)

    2014-06-15

    In order to improve the glass-forming ability (GFA) of Nd-Fe-B ternary alloys to obtain fully amorphous bulk Nd-Fe-B-based alloy, the effects of Mo and Y doping on GFA of the alloys were investigated. It was found that the substitution of Mo for Fe and Y for Nd enhanced the GFA of the Nd-Y-Fe-Mo-B alloys. It was also revealed that the GFA of the samples was optimized by 4 at.% Mo doping and increased with theYcontent. The fully amorphous structures were all formed in the Nd{sub 6-x}Y{sub x}Fe{sub 68}Mo{sub 4}B{sub 22} (x =1-5) alloy rods with 1.5 mm-diameter. After subsequent crystallization, the devitrified Nd{sub 3}Y{sub 3}Fe{sub 68}Mo{sub 4}B{sub 22} alloy rod exhibited a uniform distribution of grains with a coercivity of 364.1 kA/m. The crystallization behavior of Nd{sub 3}Y{sub 3}Fe{sub 68}Mo{sub 4}B{sub 22} BMG was investigated in isothermal situation. The Avrami exponent n determined by JAM plot is lower than 2.5, implying that the crystallization is mainly governed by a growth of particles with decreasing nucleation rate. (orig.)

  5. Crystallization kinetics and magnetic properties of FeSiCr amorphous alloy powder cores

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hu-ping [School of Logistics Engineering, Wuhan University of Technology, Wuhan 430063 (China); Wang, Ru-wu, E-mail: ruwuwang@hotmail.com [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China); College of Materials Science and Metallurgical Engineering, Wuhan University of Science and Technology, Wuhan 430081 (China); Wei, Ding [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China); Zeng, Chun [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China)

    2015-07-01

    The crystallization kinetics of FeSiCr amorphous alloy, characterized by the crystallization activation energy, Avrami exponent and frequency factor, was studied by non-isothermal differential scanning calorimetric (DSC) measurements. The crystallization activation energy and frequency factor of amorphous alloy calculated from Augis–Bennett model were 476 kJ/mol and 5.5×10{sup 18} s{sup −1}, respectively. The Avrami exponent n was calculated to be 2.2 from the Johnson–Mehl–Avrami (JMA) equation. Toroid-shaped Fe-base amorphous powder cores were prepared from the commercial FeSiCr amorphous alloy powder and subsequent cold pressing using binder and insulation. The characteristics of FeSiCr amorphous alloy powder and the effects of compaction pressure and insulation content on the magnetic properties, i.e., effective permeability μ{sub e}, quality factor Q and DC-bias properties of FeSiCr amorphous alloy powder cores, were investigated. The FeSiCr amorphous alloy powder cores exhibit a high value of quality factor and a stable permeability in the frequency range up to 1 MHz, showing superior DC-bias properties with a “percent permeability” of more than 82% at H=100 Oe. - Highlights: • The crystallization kinetics of FeSiCr amorphous alloy was investigated. • The FeSiCr powder cores exhibit a high value of Q and a stable permeability. • The FeSiCr powder cores exhibit superior DC-bias properties.

  6. Highly textured Nd-Fe-B films grown on amorphous substrates

    International Nuclear Information System (INIS)

    Hannemann, Ullrich; Melcher, Steffen; Faehler, Sebastian

    2004-01-01

    Thin films with an almost perfect alignment of Nd 2 Fe 14 B grains with the c-axis (easy magnetisation direction) perpendicular to the film plane were achieved on amorphous SiN substrates using pulsed laser deposition. The texture arises due to epitaxial growth on a Ta(1 1 0) buffer deposited prior to the Nd-Fe-B film. Out-of-plane coercivity of 1.3 T and remanence to saturation magnetisation ratio around 0.95 are obtained for Nd-rich films. An analysis of the coercivity mechanism shows that the switching mechanism is nucleation dominated, independent of the Nd content

  7. Highly textured Nd-Fe-B films grown on amorphous substrates

    Energy Technology Data Exchange (ETDEWEB)

    Hannemann, Ullrich E-mail: u.hannemann@ifw-dresden.de; Melcher, Steffen; Faehler, Sebastian

    2004-05-01

    Thin films with an almost perfect alignment of Nd{sub 2}Fe{sub 14}B grains with the c-axis (easy magnetisation direction) perpendicular to the film plane were achieved on amorphous SiN substrates using pulsed laser deposition. The texture arises due to epitaxial growth on a Ta(1 1 0) buffer deposited prior to the Nd-Fe-B film. Out-of-plane coercivity of 1.3 T and remanence to saturation magnetisation ratio around 0.95 are obtained for Nd-rich films. An analysis of the coercivity mechanism shows that the switching mechanism is nucleation dominated, independent of the Nd content.

  8. Some magnetic and magnetoresistive properties of RF-sputtered thin NiFe-Si films.

    Science.gov (United States)

    Vatskicheva, M.; Vatskichev, Ly.; Dimitrov, I.; Kunev, B.

    The galvanomagnetic properties and some structural peculiarities of rf-sputtered alloy films (NI80Fe20)100-xSix at 0 < x < 30 at. % were studied and compared with the corresponding properties of evaporated films of the same thickness and composition. The content of silicon increased with the increasing of the velocity of deposition and led to the amorphousation of the films. Coercivity decreased with the velocity of growth but it did not depend on the thickness and on the velocity of film deposition. The magnetoresistance ratio Dr/r of the sputtered films was about three times higher then that of the evaporated films.

  9. Magnetic characteristics and nanostructures of FePt granular films with GeO2 segregant

    Science.gov (United States)

    Ono, Takuya; Moriya, Tomohiro; Hatayama, Masatoshi; Tsumura, Kaoru; Kikuchi, Nobuaki; Okamoto, Satoshi; Kitakami, Osamu; Shimatsu, Takehito

    2017-01-01

    To realize a granular film composed of L10-FePt grains with high uniaxial magnetic anisotropy energy, Ku, and segregants for energy-assisted magnetic recording, a FePt-GeO2/FePt-C stacked film was investigated in the engineering process. The FePt-GeO2/FePt-C stacked film fabricated at a substrate temperature of 450 °C realized uniaxial magnetic anisotropy, Kugrain , of about 2.5 × 107 erg/cm3, which is normalized by the volume fraction of FePt grains, and a granular structure with an averaged grain size of 7.7 nm. As the thickness of the FePt-GeO2 upper layer was increased to 9 nm, the Ku values were almost constant. That result differs absolutely from the thickness dependences of the other oxide segregant materials such as SiO2 and TiO2. Such differences on the oxide segregant are attributed to their chemical bond. The strong covalent bond of GeO2 is expected to result in high Ku of the FePt-GeO2/FePt-C stacked films.

  10. Interface-enhanced high-temperature superconductivity in single-unit-cell FeT e1 -xS ex films on SrTi O3

    Science.gov (United States)

    Li, Fangsen; Ding, Hao; Tang, Chenjia; Peng, Junping; Zhang, Qinghua; Zhang, Wenhao; Zhou, Guanyu; Zhang, Ding; Song, Can-Li; He, Ke; Ji, Shuaihua; Chen, Xi; Gu, Lin; Wang, Lili; Ma, Xu-Cun; Xue, Qi-Kun

    2015-06-01

    Recently discovered high-temperature superconductivity in single-unit-cell (UC) FeSe films on SrTi O3 (STO) substrate has stimulated tremendous research interest, both experimental and theoretical. Whether this scenario could be extended to other superconductors is vital in both identifying the enhanced superconductivity mechanism and further raising the critical transition temperature (Tc). Here we successfully prepared single-UC FeT e1 -xS ex(0.1 ≤x ≤0.6 ) films on STO substrates by molecular beam epitaxy and observed U -shaped superconducting gaps (Δ ) up to ˜16.5 meV , nearly ten times the gap value (Δ ˜1.7 meV ) of the optimally doped bulk FeT e0 .6S e0 .4 single crystal (Tc˜14.5 K ). No superconducting gap has been observed on the second UC and thicker FeT e1 -xS ex films at 5.7 K, indicating the important role of the interface. This interface-enhanced high-temperature superconductivity is further confirmed by ex situ transport measurements, which revealed an onset superconducting transition temperature above 40 K, nearly two times higher than that of the optimally doped bulk FeT e0 .6S e0 .4 single crystal. This work demonstrates that interface engineering is a feasible way to discover alternative superconductors with higher Tc.

  11. Magnetic and magnetoelastic properties of epitaxial SmFe{sub 2} thin film

    Energy Technology Data Exchange (ETDEWEB)

    Fuente, C de la; Arnaudas, J I; Ciria, M; Del Moral, A [Departamento de Magnetismo de Solidos and Departamento de Fisica de la Materia Condensada, Instituto de Ciencia de los Materiales de Aragon and Universidad de Zaragoza, 50071, Zaragoza (Spain); Dufour, C; Dumesnil, K, E-mail: cesar@unizar.e [Laboratoire de Metallurgie Physique et de Science des Materiaux, Universite Henry Poincare, Nancy 1, BP 239, 54506 (France)

    2010-02-03

    We report on magnetic and magnetoelastic measurements for a 5000 A (110) SmFe{sub 2} thin film, which was successfully analyzed by means of a point charge model for describing the effect of the epitaxial growth in this kind of system. Some of the main conclusions of the Moessbauer and magnetoelastic results and the new magnetization results up to 5 T allow us to get a full description of the crystal electric field, exchange, and magnetoelastic behavior in this compound. So, new single-ion parameters are obtained for the crystal field interaction of samarium ions, A{sub 4}(r{sup 4}) = +755 K/ion and A{sub 6}(r{sup 6}) = -180 K/ion, and new single-ion magnetoelastic coupling B{sup gamma}{sup ,2}approx =-200 MPa and B{sup epsilon}{sup ,2}approx =800 MPa, which represent the tetragonal and the in-plane shear deformations, respectively. Moreover, the new thermal behavior of the samarium magnetic moment, the exchange coupling parameter, and the magnetocrystalline anisotropy of the iron sublattice are obtained too. From these, the softening of the spin reorientation transition with respect to the bulk case could be accounted for.

  12. Metal-semiconductor transition materials. FeS and VO{sub 2} thin films by RF reactive sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Fu Ganhua

    2007-06-15

    In the present work, two MST systems, FeS and VO{sub 2} thin films were investigated. Iron sulfide thin films over a range of composition were prepared by reactive sputtering. The influence of the substrate, sputter power, substrate temperature and stoichiometry on the structure and MST of iron sulfide films was investigated. Iron sulfide films deposited at different temperatures show temperature dependent structure and MST. FeS films on float glass show (110) and (112) orientations when the substrate temperature is 200 and 500 C, respectively. The transition temperature and width of the hysteresis loop determined from the temperature dependent conductivity curves of iron sulfide films decrease with the substrate temperature. Fe and S excess in FeS films both result in the decrease of the transition temperature and width of the hysteresis loop. The vacuum-annealing affects the MST of FeS films significantly. When FeS films were annealed below the deposition temperature, the transition temperature decreases; otherwise increases. The residual stress plays an important role during the annealing process. The higher the residual stress inside the FeS films is, the higher the transition temperature of FeS films. With the increase of the annealing temperature, the residual stress in FeS films is first released and then enhances, which gives rise first to the decrease and then increase of the transition temperature of FeS films. At high substrate temperatures, the residual stress is higher. In addition, the MST of FeS films was influenced by the ambient aging. With the increase of the aging time, the transition temperature first increases and then decreases. FeS films with different thicknesses were prepared. The correlation between the film thickness (grain size) and the MST switching characteristics of FeS films was established. With the decrease of the grain size, the density of grain boundaries increases, causing the increase of the conductivity of the semiconducting

  13. Metal-semiconductor transition materials. FeS and VO2 thin films by RF reactive sputtering

    International Nuclear Information System (INIS)

    Fu, Ganhua

    2007-06-01

    In the present work, two MST systems, FeS and VO 2 thin films were investigated. Iron sulfide thin films over a range of composition were prepared by reactive sputtering. The influence of the substrate, sputter power, substrate temperature and stoichiometry on the structure and MST of iron sulfide films was investigated. Iron sulfide films deposited at different temperatures show temperature dependent structure and MST. FeS films on float glass show (110) and (112) orientations when the substrate temperature is 200 and 500 C, respectively. The transition temperature and width of the hysteresis loop determined from the temperature dependent conductivity curves of iron sulfide films decrease with the substrate temperature. Fe and S excess in FeS films both result in the decrease of the transition temperature and width of the hysteresis loop. The vacuum-annealing affects the MST of FeS films significantly. When FeS films were annealed below the deposition temperature, the transition temperature decreases; otherwise increases. The residual stress plays an important role during the annealing process. The higher the residual stress inside the FeS films is, the higher the transition temperature of FeS films. With the increase of the annealing temperature, the residual stress in FeS films is first released and then enhances, which gives rise first to the decrease and then increase of the transition temperature of FeS films. At high substrate temperatures, the residual stress is higher. In addition, the MST of FeS films was influenced by the ambient aging. With the increase of the aging time, the transition temperature first increases and then decreases. FeS films with different thicknesses were prepared. The correlation between the film thickness (grain size) and the MST switching characteristics of FeS films was established. With the decrease of the grain size, the density of grain boundaries increases, causing the increase of the conductivity of the semiconducting phase

  14. Effect of surfactants on the morphology of FeSe films fabricated from ...

    Indian Academy of Sciences (India)

    tants in gas phase, aerosol- assisted chemical vapour deposition (AACVD) ... temperature, flow rate, concentration of the precursor, ... chemical sensing and photocatalytic activity in FeSe films ... having ultrasonic system on glass substrates.

  15. Magnetic and magneto-optical properties of FeRh thin films

    International Nuclear Information System (INIS)

    Inoue, Sho; Nam, Nguyen T.; Phuoc, Nguyen N.; Cao Jiangwei; Yu Ko, Hnin Yu; Suzuki, Takao

    2008-01-01

    The magnetic and magneto-optical properties of FeRh thin films epitaxially deposited onto MgO(1 0 0) substrates by RF sputter-deposition system have been investigated in conjunction with the structure. An intriguing virgin effect has been found in the M-T curves of the as-deposited FeRh thin films, which is presumably interpreted in term of a change in structural phase when heating. Also, a (negative) maximum peak of Kerr rotation at around 3.8 eV has been observed when FeRh thin films are in ferromagnetic state. The polar Kerr rotation angle is found to increase at temperatures above 100 deg. C, which corresponds to the antiferromagnet (AF)-ferromagnet (FM) transition of FeRh thin films

  16. Spacer layer effect and microstructure on multi-layer [NdFeB/Nb]n films

    International Nuclear Information System (INIS)

    Tsai, J.-L.; Yao, Y.-D.; Chin, T.-S.; Kronmueller, H.

    2002-01-01

    Spacer layer effect on multi-layer [NdFeB/Nb] n films has been investigated from the variation of magnetic properties and microstructure of the films. From a HRTEM cross-section view observation, the average grain size of [NdFeB/Nb] n multi-layers was controlled by both annealing temperature and thickness of NdFeB layer. Selected area diffraction pattern indicated that the structure of Nb spacer layer was amorphous. The grain size and coercivity of [NdFeB x /Nb] n films change from 50 nm and 16.7 kOe to 167 nm and 9 kOe for films with x=40 nm, n=10 and x=200 nm, n=2, respectively

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

    KAUST Repository

    Yao, Yingbang; Zhang, Bei; Chen, Long; Yang, Yang; Wang, Zhihong; Alshareef, Husam N.; Zhang, Xixiang

    2012-01-01

    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

  18. Third generation biosensing matrix based on Fe-implanted ZnO thin film

    International Nuclear Information System (INIS)

    Saha, Shibu; Gupta, Vinay; Sreenivas, K.; Tan, H. H.; Jagadish, C.

    2010-01-01

    Third generation biosensor based on Fe-implanted ZnO (Fe-ZnO) thin film has been demonstrated. Implantation of Fe in rf-sputtered ZnO thin film introduces redox center along with shallow donor level and thereby enhance its electron transfer property. Glucose oxidase (GOx), chosen as model enzyme, has been immobilized on the surface of the matrix. Cyclic voltammetry and photometric assay show that the prepared bioelectrode, GOx/Fe-ZnO/ITO/Glass is sensitive to the glucose concentration with enhanced response of 0.326 μA mM -1 cm -2 and low Km of 2.76 mM. The results show promising application of Fe-implanted ZnO thin film as an attractive matrix for third generation biosensing.

  19. Third generation biosensing matrix based on Fe-implanted ZnO thin film

    Science.gov (United States)

    Saha, Shibu; Gupta, Vinay; Sreenivas, K.; Tan, H. H.; Jagadish, C.

    2010-09-01

    Third generation biosensor based on Fe-implanted ZnO (Fe-ZnO) thin film has been demonstrated. Implantation of Fe in rf-sputtered ZnO thin film introduces redox center along with shallow donor level and thereby enhance its electron transfer property. Glucose oxidase (GOx), chosen as model enzyme, has been immobilized on the surface of the matrix. Cyclic voltammetry and photometric assay show that the prepared bioelectrode, GOx/Fe-ZnO/ITO/Glass is sensitive to the glucose concentration with enhanced response of 0.326 μA mM-1 cm-2 and low Km of 2.76 mM. The results show promising application of Fe-implanted ZnO thin film as an attractive matrix for third generation biosensing.

  20. Permanent magnetic properties of NdFe12Nx sputtered films epitaxially grown on V buffer layer

    Science.gov (United States)

    Sato, T.; Ohsuna, T.; Yano, M.; Kato, A.; Kaneko, Y.

    2017-08-01

    To clarify the magnetic properties of the NdFe12Nx compound, which shows promise as a high-performance permanent magnet material, NdFe12Nx epitaxial films fabricated by using a V underlayer on MgO (100) single-crystalline substrates were investigated. Nd-Fe films deposited on a V underlayer consist of NdFe12 grains, which have a c-axis orientation perpendicular to the film plane, as well as α-Fe and Nd2Fe17 phases. In the Nd-Fe-N film obtained by subsequent nitridation of the Nd-Fe film, NdFe12Nx grains grew as the dominant phase, and the volume fractions of α-Fe phases dropped below 5%. A Nd-Fe-N film with a thickness of 50 nm exhibits a saturation magnetization (Ms) of 1.7 T, an anisotropy field (HA) of ˜60 kOe, a magnetocrystalline anisotropy energy (K1) of ˜4.1 MJ/m3, and a coercivity (Hc) of 1.7 kOe. The Hc of a Nd-Fe-N film with a thickness of 25 nm is 4.3 kOe. These results indicate that NdFe12Nx compounds have a superior Ms compared to Nd-Fe-B magnets, while the enhancement in Hc is indispensable.

  1. Magnetron sputtering of Fe-oxides on the top of HTS YBCO films

    International Nuclear Information System (INIS)

    Nurgaliev, T.; Blagoev, B.; Buchkov, K.; Mateev, E.; Gajda, G.; Nedkov, I.; Kovacheva, D.; Slavov, L.; Starbova, I.; Starbov, N.; Nankovski, M.

    2017-01-01

    The possibilities for preparation of bilayers containing magnetic Fe-oxide (Fe-O) and high temperature superconducting (HTS) YBa 2 Cu 3 O 7−x (YBCO) thin films were investigated. For this purpose, Fe-O films were deposited using reactive magnetron sputtering at comparatively low temperatures T≤250 °C onto dielectric (for example, LaAlO 3 (LAO)) substrates, covered with a HTS YBCO film. The sputtering of the Fe-O layer at such conditions did not lead to a crucial damage of the critical temperature T C of the YBCO film, but could affect the width of the superconducting transition. A decrease of the critical temperature of the (Fe-O)/YBCO/LAO bilayer kept at ambient conditions was observed, possibly due to the negative effects of the water vapour on the sample characteristics. The double peak structure of the imaginary component of the response signal to the AC harmonic magnetic field, observed in such a (Fe-O)/YBCO/LAO sample, was ascribed from two possible views: as a consequence of morphology determined inter- and intra-granular contributions and/or as transitions from dominant irreversible processes as Bean-Livingston barrier to vortex state chains formation. - Highlights: • Iron-oxide (Fe-O) film sputtered on the top of superconducting HTS YBCO film at not very high temperatures. • No crucially damaged superconducting properties of YBCO film during Fe-O sputtering process. • A negative effect of the ambient conditions on the critical temperature of the obtained samples. • A double peak structure of the response signal to the AC harmonic magnetic field in a (Fe-O)/YBCO/LAO is observed.

  2. Magnetron sputtering of Fe-oxides on the top of HTS YBCO films

    Energy Technology Data Exchange (ETDEWEB)

    Nurgaliev, T. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Blagoev, B. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Laboratory of High Magnetic Fields and Low Temperatures, 95 Gajowicka Str., 53-421 Wroclaw (Poland); Buchkov, K. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Mateev, E. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Gajda, G. [Laboratory of High Magnetic Fields and Low Temperatures, 95 Gajowicka Str., 53-421 Wroclaw (Poland); Nedkov, I. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Kovacheva, D. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Street, bl. 10, 1113 Sofia (Bulgaria); Slavov, L. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Laboratory of High Magnetic Fields and Low Temperatures, 95 Gajowicka Str., 53-421 Wroclaw (Poland); Starbova, I.; Starbov, N. [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Nankovski, M. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chausse, 1784 Sofia (Bulgaria); Sofia university “St. Kliment Ohridski”, Faculty of Physics, 5 James Bourchier Blvd., 1164 Sofia (Bulgaria)

    2017-05-01

    The possibilities for preparation of bilayers containing magnetic Fe-oxide (Fe-O) and high temperature superconducting (HTS) YBa{sub 2}Cu{sub 3}O{sub 7−x} (YBCO) thin films were investigated. For this purpose, Fe-O films were deposited using reactive magnetron sputtering at comparatively low temperatures T≤250 °C onto dielectric (for example, LaAlO{sub 3} (LAO)) substrates, covered with a HTS YBCO film. The sputtering of the Fe-O layer at such conditions did not lead to a crucial damage of the critical temperature T{sub C} of the YBCO film, but could affect the width of the superconducting transition. A decrease of the critical temperature of the (Fe-O)/YBCO/LAO bilayer kept at ambient conditions was observed, possibly due to the negative effects of the water vapour on the sample characteristics. The double peak structure of the imaginary component of the response signal to the AC harmonic magnetic field, observed in such a (Fe-O)/YBCO/LAO sample, was ascribed from two possible views: as a consequence of morphology determined inter- and intra-granular contributions and/or as transitions from dominant irreversible processes as Bean-Livingston barrier to vortex state chains formation. - Highlights: • Iron-oxide (Fe-O) film sputtered on the top of superconducting HTS YBCO film at not very high temperatures. • No crucially damaged superconducting properties of YBCO film during Fe-O sputtering process. • A negative effect of the ambient conditions on the critical temperature of the obtained samples. • A double peak structure of the response signal to the AC harmonic magnetic field in a (Fe-O)/YBCO/LAO is observed.

  3. Electrical transport properties in Fe-Cr nanocluster-assembled granular films

    Science.gov (United States)

    Wang, Xiong-Zhi; Wang, Lai-Sen; Zhang, Qin-Fu; Liu, Xiang; Xie, Jia; Su, A.-Mei; Zheng, Hong-Fei; Peng, Dong-Liang

    2017-09-01

    The Fe100-xCrx nanocluster-assembled granular films with Cr atomic fraction (x) ranging from 0 to 100 were fabricated by using a plasma-gas-condensation cluster deposition system. The TEM characterization revealed that the uniform Fe clusters were coated with a Cr layer to form a Fe-Cr core-shell structure. Then, the as-prepared Fe100-xCrx nanoclusters were randomly assembled into a granular film in vacuum environments with increasing the deposition time. Because of the competition between interfacial resistance and shunting effect of Cr layer, the room temperature resistivity of the Fe100-xCrx nanocluster-assembled granular films first increased and then decreased with increasing the Cr atomic fraction (x), and revealed a maximum of 2 × 104 μΩ cm at x = 26 at.%. The temperature-dependent longitudinal resistivity (ρxx), magnetoresistance (MR) effect and anomalous Hall effect (AHE) of these Fe100-xCrx nanocluster-assembled granular films were also studied systematically. As the x increased from 0 to 100, the ρxx of all samples firstly decreased and then increased with increasing the measuring temperature. The dependence of ρxx on temperature could be well addressed by a mechanism incorporated for the fluctuation-induced-tunneling (FIT) conduction process and temperature-dependent scattering effect. It was found that the anomalous Hall effect (AHE) had no legible scaling relation in Fe100-xCrx nanocluster-assembled granular films. However, after deducting the contribution of tunneling effect, the scaling relation was unambiguous. Additionally, the Fe100-xCrx nanocluster-assembled granular films revealed a small negative magnetoresistance (MR), which decreased with the increase of x. The detailed physical mechanism of the electrical transport properties in these Fe100-xCrx nanocluster-assembled granular films was also studied.

  4. First-principles-based study of transport properties of Fe thin films on Cu surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kishi, Tomoya [Department of Applied Physics, Osaka University, Suita, Osaka 565-0871 (Japan); Kasai, Hideaki [Department of Applied Physics, Osaka University, Suita, Osaka 565-0871 (Japan); Nakanishi, Hiroshi [Department of Applied Physics, Osaka University, Suita, Osaka 565-0871 (Japan); Dino, Wilson Agerico [Department of Applied Physics, Osaka University, Suita, Osaka 565-0871 (Japan); Komori, Fumio [Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8587 (Japan)

    2004-12-08

    We investigate the transport properties of Fe thin films on Cu(111) based on first principles calculation. We calculate the electron current through these Fe thin films, which can be observed by using a double-tipped scanning tunnelling microscope. We find that the conductance is majority spin polarized. On the basis of the band structures for this system, we discuss the origin of these interesting transport properties.

  5. First-principles-based study of transport properties of Fe thin films on Cu surfaces

    International Nuclear Information System (INIS)

    Kishi, Tomoya; Kasai, Hideaki; Nakanishi, Hiroshi; Dino, Wilson Agerico; Komori, Fumio

    2004-01-01

    We investigate the transport properties of Fe thin films on Cu(111) based on first principles calculation. We calculate the electron current through these Fe thin films, which can be observed by using a double-tipped scanning tunnelling microscope. We find that the conductance is majority spin polarized. On the basis of the band structures for this system, we discuss the origin of these interesting transport properties

  6. Epitactical FeAl films on sapphire and their magnetic properties

    International Nuclear Information System (INIS)

    Trautvetter, Moritz

    2011-01-01

    In the presented thesis epitaxial FeAl thin films on sapphire have been prepared by pulse laser deposition (PLD). The thin films deposited at room temperature exhibits ferromagnetism and subsequent annealing is necessary to transform the thin films to paramagnetic B2-phase, where the transition temperature depends on the crystalline orientation of the sapphire substrate. Alternatively, by deposition at higher substrate temperature the B2-phase is obtained directly. However, morphology of the FeAl film is influenced by different growth modes resulting from different substrate temperatures. The paramagnetic FeAl films can then be transformed to ferromagnetic phase by successive ion irradiation. Independent of the ion species used for irradiation, the same universal relation between thin films' coercive fields and irradiation damage is identified. The ion irradiation ferromagnetism can be transformed back to paramagnetism by subsequent annealing. The mutual transition between ferromagnetic and paramagnetic phases has been performed several times and shows full reversibility. The ferromagnetic phase induced by Kr + irradiation exhibits structural relaxation, where the saturate magnetization of FeAl thin film gradually decreases in several days. Later, ion irradiation has been performed selectively on defined areas of the thin film with the help of an unconventional lithography technique. The subsequent thin film is composed of ordered hexagonal array of ferromagnetic nano-cylinders separated by a paramagnetic matrix, suggesting a promising system for magnetic data storage. (orig.)

  7. Comparison of functional parameters of CsI:Tl crystals and thick films

    International Nuclear Information System (INIS)

    Fedorov, A.; Gektin, A.; Lebedynskiy, A.; Mateychenko, P.; Shkoropatenko, A.

    2013-01-01

    500 mkm thick CsI:Tl columnar films can be produced using thermal evaporation in vacuum by sublimation of the same bulk crystal. Comparison of afterglow and radiation stability of deposited CsI:Tl films with source crystal was the aim of current work. It is shown that the afterglow in the films is always below its level in initial single crystal. It was ascertained that the annealing atmospheres influence the processes leading to the activator depletion of the films during the thermal processing. -- Highlights: ► Thick CsI:Tl columnar films were obtained by thermal evaporation in vacuum. ► Radiation stability of such CsI:Tl films appears to be better than that of crystal. ► CsI:Tl film parameters can be modified by annealing in different atmospheres

  8. Mechanical design of thin-film diamond crystal mounting apparatus with optimized thermal contact and crystal strain for coherence preservation x-ray optics

    Science.gov (United States)

    Shu, Deming; Shvydko, Yury; Stoupin, Stanislav; Kim, Kwang-Je

    2018-05-08

    A method and mechanical design for a thin-film diamond crystal mounting apparatus for coherence preservation x-ray optics with optimized thermal contact and minimized crystal strain are provided. The novel thin-film diamond crystal mounting apparatus mounts a thin-film diamond crystal supported by a thick chemical vapor deposition (CVD) diamond film spacer with a thickness slightly thicker than the thin-film diamond crystal, and two groups of thin film thermal conductors, such as thin CVD diamond film thermal conductor groups separated by the thick CVD diamond spacer. The two groups of thin CVD film thermal conductors provide thermal conducting interface media with the thin-film diamond crystal. A piezoelectric actuator is integrated into a flexural clamping mechanism generating clamping force from zero to an optimal level.

  9. Moessbauer determination of magnetic structure of Fe3BO6 crystal

    International Nuclear Information System (INIS)

    Kovalenko, P.P.; Labushkin, V.G.; Ovsepyan, A.K.; Sarkisov, Eh.R.; Smirnov, E.V.; Prokopov, A.R.; Seleznev, V.N.

    1984-01-01

    The magnetic structure of a Fe 3 BO 6 crystal belonging to space group Dsub(2h)sup(16)(Psub(nma)) is determined by the Moessbauer γ-radiation diffraction. The bragg reflection (700) of Moessbauer 14.4 keV γ-quanta from the Fe 3 BO 6 monocrystal has been studied experimentally. A high sensitivity of the interference of γ-quantum diffraction scattering on Fe nuclei being in crystallographically non-equivalent 8d- and 4s-positions to the type of magnetic ordering in the crystal is used for determination of the magnetic structure. Agreement of the experimental results with the theoretical calculations, conducted for types of magnetic ordering resolved by the symmetry of the crystal, permitted to reliably determine the magnetic structure of this compound. The results obtained confirm the data of neutrondiffraction studies on magnetic ordering in Fe 3 BO 6 . Advantages of the Moessbauer-diffraction study, as compared to the magnetic neutrondiffraction method, in particular, for investigation of crystals, in which the hyperfine magnetic fields on Fe nuclei have different values, are revealed and discussed in detail

  10. Moessbauer determination of magnetic structure of Fe/sub 3/BO/sub 6/ crystal

    Energy Technology Data Exchange (ETDEWEB)

    Kovalenko, P.P.; Labushkin, V.G.; Ovsepyan, A.K.; Sarkisov, Eh.R.; Smirnov, E.V.; Prokopov, A.R.; Seleznev, V.N.

    1984-10-01

    The magnetic structure of a Fe/sub 3/BO/sub 6/ crystal belonging to space group Dsub(2h)sup(16)(Psub(nma)) is determined by the Moessbauer ..gamma..-radiation diffraction. The bragg reflection (700) of Moessbauer 14.4 keV ..gamma..-quanta from the Fe/sub 3/BO/sub 6/ monocrystal has been studied experimentally. A high sensitivity of the interference of ..gamma..-quantum diffraction scattering on Fe nuclei being in crystallographically non-equivalent 8d- and 4s-positions to the type of magnetic ordering in the crystal is used for determination of the magnetic structure. Agreement of the experimental results with the theoretical calculations, conducted for types of magnetic ordering resolved by the symmetry of the crystal, permitted to reliably determine the magnetic structure of this compound. The results obtained confirm the data of neutrondiffraction studies on magnetic ordering in Fe/sub 3/BO/sub 6/. Advantages of the Moessbauer-diffraction study, as compared to the magnetic neutrondiffraction method, in particular, for investigation of crystals, in which the hyperfine magnetic fields on Fe nuclei have different values, are revealed and discussed in detail.

  11. Crystal structure and magnetic properties of Tb6FeSb2

    International Nuclear Information System (INIS)

    Cai Gemei; Zhang Jiliang; He Wei; Qin Pingli; Zeng Lingmin

    2006-01-01

    The crystal structure and magnetic properties of Tb 6 FeSb 2 has been investigated for the first time. The compound crystallizes in the hexagonal, space group P6-bar 2m (No. 189) with the Ho 6 FeSb 2 structure type and lattice parameters a=8.1942(5)A, c=4.1758(3)A, z=1 and D calc =8.564g/cm 3 . Its magnetic properties were measured between 85 and 420K. The Curie temperature T c =256K was obtained using the method of intersecting tangents, and the effective paramagnetic moment was μ eff =9.32μ B per Tb atom

  12. Praseodymium Cuprate Thin Film Cathodes for Intermediate Temperature Solid Oxide Fuel Cells: Roles of Doping, Orientation, and Crystal Structure.

    Science.gov (United States)

    Mukherjee, Kunal; Hayamizu, Yoshiaki; Kim, Chang Sub; Kolchina, Liudmila M; Mazo, Galina N; Istomin, Sergey Ya; Bishop, Sean R; Tuller, Harry L

    2016-12-21

    Highly textured thin films of undoped, Ce-doped, and Sr-doped Pr 2 CuO 4 were synthesized on single crystal YSZ substrates using pulsed laser deposition to investigate their area-specific resistance (ASR) as cathodes in solid-oxide fuel cells (SOFCs). The effects of T' and T* crystal structures, donor and acceptor doping, and a-axis and c-axis orientation on ASR were systematically studied using electrochemical impedance spectroscopy on half cells. The addition of both Ce and Sr dopants resulted in improvements in ASR in c-axis oriented films, as did the T* crystal structure with the a-axis orientation. Pr 1.6 Sr 0.4 CuO 4 is identified as a potential cathode material with nearly an order of magnitude faster oxygen reduction reaction kinetics at 600 °C compared to thin films of the commonly studied cathode material La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ . Orientation control of the cuprate films on YSZ was achieved using seed layers, and the anisotropy in the ASR was found to be less than an order of magnitude. The rare-earth doped cuprate was found to be a versatile system for study of relationships between bulk properties and the oxygen reduction reaction, critical for improving SOFC performance.

  13. Thin (111) oriented CoFe{sub 2}O{sub 4} and Co{sub 3}O{sub 4} films prepared by decomposition of layered cobaltates

    Energy Technology Data Exchange (ETDEWEB)

    Buršík, Josef, E-mail: bursik@iic.cas.cz [Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., 250 68 Husinec-Řež 1001 (Czech Republic); Soroka, Miroslav, E-mail: soroka@iic.cas.cz [Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., 250 68 Husinec-Řež 1001 (Czech Republic); Uhrecký, Róbert, E-mail: uhrecky@iic.cas.cz [Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, v.v.i., 250 68 Husinec-Řež 1001 (Czech Republic); Kužel, Radomír, E-mail: kuzel@karlov.mff.cuni.cz [Charles University in Prague, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Praha 2 (Czech Republic); Mika, Filip, E-mail: filip.mika@isibrno.cz [Institute of Scientific Instruments, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 147, 612 64 Brno (Czech Republic); Huber, Štěpán, E-mail: stepan.huber@vscht.cz [University of Chemistry and Technology, Faculty of Chemical Technology, Technická 5, 166 28 Prague 6 (Czech Republic)

    2016-07-15

    Graphical abstract: Pole figures of NaCoO{sub 2} (left) and of CoFe{sub 2}O{sub 4} (right) films formed through the transformation of O3-type NaCoO{sub 2} phase in consequence of sodium deintercalation occurring at 800 °C. Films were prepared by chemical solution deposition on MgO(111) substrate. - Highlights: • Epitaxial Na(CoFe)O{sub 2} thin films by means of chemical solution deposition were prepared. • Oriented spinel films through transformation of Na(CoFe)O{sub 2} were obtained. • Orientation relation to MgO, SrTiO{sub 3} and Zr(Y)O{sub 2} substrates were determined. • Structural aspects of Na(CoFe)O{sub 2} → CoFe{sub 2}O{sub 4} transformation pathway were elucidated. - Abstract: The formation and structural characterization of highly (111)-oriented Co{sub 3}O{sub 4} and CoFe{sub 2}O{sub 4} films prepared by a novel procedure from 00l-oriented NaCoO{sub 2} and Na(CoFe)O{sub 2} is reported. The Na(CoFe)O{sub 2} films were deposited on MgO, SrTiO{sub 3}, LaAlO{sub 3}, and Zr(Y)O{sub 2} single crystals with (100) and (111) orientations by chemical solution deposition method and crystallized at 700 °C. Subsequently they were transformed into (111)-oriented spinel phase during post-growth annealing at 800–1000 °C. Morphology and structure of the films was investigated by means of scanning electron microscopy and X-ray diffraction. While all spinel films exhibit pronounced out-of-plane orientation irrespective of substrate, the rate of in-plane orientation strongly depend on lattice misfit values. Different epitaxial phenomena ranging from true one-to-one epitaxy to the existence of many-to-one epitaxy involving two or more orientations were determined by full 3D texture analysis.

  14. Study of microstructure and magnetic properties of L10 FePt/SiO2 thin films

    Directory of Open Access Journals (Sweden)

    Giannopoulos G.

    2014-07-01

    Full Text Available Achieving magnetic recording densities in excess of 1Tbit/in2 requires not only perpendicular media with anisotropies larger than 7 MJ/m3, making FePt alloys an ideal choice, but also a narrow distribution below 10 nm for a reduced S/N ratio. Such grain size reduction and shape control are crucial parameters for high density magnetic recording, along with high thermal stability. Previous work has shown that the L10 FePt grain size can be controlled by alloying FePt with materials such as C, Ag, and insulators such as AlOx, MgO. Au and Al2O3 also act to segregate and magnetically decouple the FePt grains. Better results were obtained with C with respect to the uniformity of grains and SiO2 with respect to the shape. We present our results on co-sputtering FePt with C or SiO2 (up to 30 vol % on MgO (001 single crystal substrates at 350 and 500 oC. With C or SiO2 addition we achieved grain size reduction, shape control and isolated structure formation, producing continuous films with high uniformity and a narrow grain size distribution. These additions thus allow us to simultaneously control the coercivity and the S/N ratio. We also will report structural and microstructural properties.

  15. Effects of annealing and pulse plating on soft magnetic properties of electroplated Fe-Ni films

    Directory of Open Access Journals (Sweden)

    T. Yanai

    2016-05-01

    Full Text Available We have already reported that Fe-Ni films prepared in citric-acid-based plating baths show good soft magnetic properties. In this paper, we investigated the effect of the grain size of the Fe-Ni crystalline phase in the films on magnetic properties, and employed an annealing and a pulse plating method in order to vary the grain size. The coercivity of the annealed Fe-Ni films at 600 °C shows large value, and good correlation between the grain growth and the coercivity was observed. The pulse plating enables us to reduce the grain size of the as-plated Fe-Ni films compared with the DC plating method, and we realized smooth surface and low coercivity of the Fe-Ni films using the pulse plating method. From these results, we confirmed the importance of the reduction in the grain size, and concluded that a pulse plating is an effective method to improve the good soft magnetic properties for our previously-reported Fe-Ni films.

  16. Direct growth of superconducting NdFeAs(O,F) thin films by MBE

    Energy Technology Data Exchange (ETDEWEB)

    Chihara, Masashi, E-mail: chihara@iku.xtal.nagoya-u.ac.jp [Department of Crystalline Materials Science, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan); Sumiya, Naoki; Arai, Kenta [Department of Crystalline Materials Science, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan); Ichinose, Ataru; Tsukada, Ichiro [Central Research Institute of Electric Power Industry, Yokosuka-shi, Kanagawa 240-0101 (Japan); Hatano, Takafumi; Iida, Kazumasa; Ikuta, Hiroshi [Department of Crystalline Materials Science, Nagoya University, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-11-15

    Highlights: • Highly textured NdFeAs(O,F) thin films were obtained by a direct growth method. • Enhancing the migration was crucial to realize the direct growth. • The critical current density exceeded 3 MA/cm{sup 2} at self-field and 1 MA/cm{sup 2} at 9 T. • A two-dimensional growth was confirmed by the observation of surface morphology. - Abstract: We report on the growth of NdFeAs(O,F) superconducting thin films by molecular beam epitaxy without having a NdOF secondary layer that was necessary for fluorine doping in our previous studies. The key to realizing the direct growth of a superconducting film was the enhancement of migration of the raw materials on the substrate, which was accomplished by two steps. Firstly, we increased the growth temperature that improved the crystalline quality of parent NdFeAsO thin films. Secondly, the atmosphere in the chamber during the growth was improved by changing the crucible material of the Fe source cell. Highly textured NdFeAs(O,F) thin films with critical temperatures up to 50 K were obtained, and terraces were observed by atomic force microscope, indicating a two-dimensional growth. However, precipitates were also found on the surface, which suggests that enhancing further the migration is necessary for obtaining a NdFeAs(O,F) thin film with a better quality.

  17. Structural, mechanical and magnetic study on galvanostatic electroplated nanocrystalline NiFeP thin films

    Science.gov (United States)

    Kalaivani, A.; Senguttuvan, G.; Kannan, R.

    2018-03-01

    Nickel based alloys has a huge applications in microelectronics and micro electromechanical systems owing to its superior soft magnetic properties. With the advantages of simplicity, cost-effectiveness and controllable patterning, electroplating processes has been chosen to fabricate thin films in our work. The soft magnetic NiFeP thin film was successfully deposited over the surface of copper plate through galvanostatic electroplating method by applying constant current density of 10 mA cm-2 for a deposition rate for half an hour. The properties of the deposited NiFeP thin films were analyzed by subjecting it into different physio-chemical characterization such as XRD, SEM, EDAX, AFM and VSM. XRD pattern confirms the formation of NiFeP particles and the structural analysis reveals that the NiFeP particles were uniformly deposited over the surface of copper substrate. The surface roughness analysis of the NiFeP films was done using AFM analysis. The magnetic studies and the hardness of the thin film were evaluated from the VSM and hardness test. The NiFeP thin films possess lower coercivity with higher magnetization value of 69. 36 × 10-3 and 431.92 Gauss.

  18. Thick Fe2O3, Fe3O4 films prepared by the chemical solution deposition method

    Czech Academy of Sciences Publication Activity Database

    Buršík, Josef; Košovan, P.; Šubrt, Jan

    2006-01-01

    Roč. 39, č. 2 (2006), s. 85-94 ISSN 0928-0707 R&D Projects: GA ČR GA203/01/0408 Institutional research plan: CEZ:AV0Z40320502 Keywords : chemical solution deposition * thick films * alpha-Fe2O3 Subject RIV: CA - Inorganic Chemistry Impact factor: 1.009, year: 2006

  19. Magnetron-sputter deposition of Fe3S4 thin films and their conversion into pyrite (FeS2) by thermal sulfurization for photovoltaic applications

    International Nuclear Information System (INIS)

    Liu Hongfei; Chi Dongzhi

    2012-01-01

    The authors report on the fabrication of FeS 2 (pyrite) thin films by sulfurizing Fe 3 S 4 that were deposited by direct current magnetron sputtering at room temperature. Under the selected sputtering conditions, Fe 3 S 4 nanocrystal films are obtained and the nanocrystals tend to locally cluster and closely pack into ricelike nanoparticles with an increase in film thickness. Meanwhile, the film tends to crack when the film thickness is increased over ∼1.3 μm. The film cracking can be effectively suppressed by an introduction of a 3-nm Cu intermediate layer prior to Fe 3 S 4 deposition. However, an introduction of a 3-nm Al intermediate layer tends to enhance the film cracking. By post-growth thermal sulfurization of the Fe 3 S 4 thin films in a tube-furnace, FeS 2 with high phase purity, as determined by using x ray diffraction, is obtained. Optical absorption spectroscopy was employed to characterize the resultant FeS 2 thin films, which revealed two absorption edges at 0.9 and 1.2 eV, respectively. These two absorption edges are assigned to the direct bandgap (0.9 eV) and the indirect allowed transitions (1.2 eV) of FeS 2 , respectively.

  20. Magnetic properties of electroplated nano/microgranular NiFe thin films for rf application

    NARCIS (Netherlands)

    Zhuang, Y.; Vroubel, M.; Rejaei, B.; Burghartz, J.N.; Attenborough, K.

    2005-01-01

    A granular NiFe thin film with large in-plane magnetic anisotropy and high ferromagnetic-resonance frequency developed for radio-frequency integrated circuit (IC) applications is presented. During the deposition, three-dimensional (3D) growth occurs, yielding NiFe grains (? ? 1.0??m). Nanonuclei (?

  1. A study on electrodeposited NixFe1−x alloy films

    Indian Academy of Sciences (India)

    Several techniques such as X-ray diffraction [9], VSM. [10], Mössbauer spectroscopy [11], four-point probe [12] etc. are used to investigate the crystallographic, magnetic and magnetotransport properties of NiFe systems. In this study our aim is to prepare NiFe alloy films relatively thicker (in µm scale) than those reported in ...

  2. Preparation and characterization of sputtered Fe1-xN x films

    International Nuclear Information System (INIS)

    Easton, E. Bradley; Buhrmester, Th.; Dahn, J.R.

    2005-01-01

    Iron nitride films have been prepared by reactive DC magnetron sputtering. The composition of Fe 1-x N x was varied over a range of 0 ≤ x ≤ 0.5 by controlling the nitrogen flow rate during sputtering. These films were characterized using powder X-ray diffraction (XRD), thermogravimetric and electron microprobe analysis. We found that the nitrogen content in the films increased with nitrogen gas partial pressure. XRD experiments revealed an evolution through the α-Fe, γ'-Fe 4 N, ε-Fe 2+z N, ζ-Fe 2 N, γ'''-FeN and γ'-FeN phases, when the nitrogen gas mole percentage was increased from 0% up to 70%. Above 70%, only the γ'-FeN phase was formed despite a measurable increase in the nitrogen content of the film with nitrogen gas partial pressure. Rietveld analysis of powder X-ray diffraction patterns revealed that this behavior is due to an increase in the nitrogen site occupation factor within the lattice

  3. Orientation control and thermoelectric properties of FeSb2 films

    DEFF Research Database (Denmark)

    Sun, Ye; Zhang, Eryun; Johnsen, Simon

    2010-01-01

    FeSb2 has a high potential for technological applications due to its colossal thermoelectric power, giant carrier mobility and large magnetoresistance. Earlier, growth of lang1 0 1rang-textured FeSb2 films on quartz (0 0 0 1) substrates has been reported. Here magnetron sputtering is used to obtain...

  4. Effect of Fe2+ and Fe3+ substitution on the crystal structure, optical and magnetic properties of anatase Ti1-δ (δ %Fe2+)O2 nanoparticles

    International Nuclear Information System (INIS)

    Wisnu Ari Adi; Adel Fisli

    2018-01-01

    Recently electromagnetic wave absorber materials are becoming a very interesting study to be studied more deeply because it is unique in terms of its interaction with electromagnetic waves itself. The main requirement to be met as an electromagnetic wave absorber material is that the material must have the characteristics of dielectric loss and magnetic loss are high. Anatase TiO 2 is a good dielectric material but these material is diamagnetic. Fe substitution was expected to manipulate the magnetic properties of this material. Modification of anatase TiO 2 was prepared by the precipitation method through the procedure as follows: 25 ml of iron salt solution containing 0.3 M Fe 2+ and 0.3 M Fe 3+ (mol ratio of 2 : 1) respectively mixed into 50 ml of 3 M TiCl 4 . The mixture solution of titanium and iron was added to a 150 ml solution of 2.5 M ammonia with drop wise rate 3 ml/min. After that the precipitate was washed then heated in an oven and calcined at 500 °C for 3 hours. There are two types of samples obtained namely anatase Ti 1-δ (δ %Fe 3+ ) Ti 1-δ (δ %Fe 2+ ) where (δ =0, 0.5, 1, and 5 wt %). Phase identification was measured by X-ray diffraction and crystal structure was analyzed by using the Rietveld method. Refinement result indicates that the sample has tetragonal crystal structure a single phase of anatase TiO 2 . Fe atoms have been successfully substituted into Ti without changing the crystal structure of this material. While based on the results of the analysis of optical and magnetic properties showed that the substitution effect of both Fe 2+ and Fe 3+ has managed to reduce energy of band gap and can transform this magnetic phase of this material from diamagnetic becomes paramagnetic at room temperature. It was concluded that it has successfully carried out material engineering of anatase TiO 2 with a substitution of up to 5 wt % of either Fe 2+ or Fe 3+ into ion Ti 4+ by the precipitation method. (author)

  5. Bulk Superconductivity and Disorder in Single Crystals of LaFePO

    Energy Technology Data Exchange (ETDEWEB)

    Analytis, James G.; Chu, Jiun-Haw; Erickson, Ann S.; Kucharczyk, Chris; /Stanford U., Appl. Phys. Dept.; Serafin, Alessandro; Carrington, Antony; /Bristol U.; Cox, Catherine; Kauzlarich, Susan M.; Hope, Hakon; /UC, Davis. Dept. Chem.

    2010-02-15

    We have studied the intrinsic normal and superconducting properties of the oxypnictide LaFePO. These samples exhibit bulk superconductivity and the evidence suggests that stoichiometric LaFePO is indeed superconducting, in contrast to other reports. We find that superconductivity is independent of the interplane residual resistivity {rho}{sub 0} and discuss the implications of this on the nature of the superconducting order parameter. Finally we find that, unlike T{sub c}, other properties in single-crystal LaFePO including the resistivity and magnetoresistance, can be very sensitive to disorder.

  6. Critical current densities and vortex dynamics in FeTexSe1-x single crystals

    International Nuclear Information System (INIS)

    Taen, T.; Tsuchiya, Y.; Nakajima, Y.; Tamegai, T.

    2010-01-01

    The critical current density and the normalized relaxation rate are reported in FeTe 0.59 Se 0.41 single crystal. Critical current density is of order of 10 5 A/cm 2 , which is comparable to that in Co-doped BaFe 2 As 2 . In low temperature and low field region, the vortex dynamics of this system is well defined by the collective creep theory, which is quite similar to Co-doped BaFe 2 As 2 reported before. We also discuss the origin of the anomaly in the field dependence of the relaxation rate.

  7. Stress-Induced Crystallization of Ge-Doped Sb Phase-Change Thin Films

    NARCIS (Netherlands)

    Eising, Gert; Pauza, Andrew; Kooi, Bart J.

    The large effects of moderate stresses on the crystal growth rate in Ge-doped Sb phase-change thin films are demonstrated using direct optical imaging. For Ge6Sb94 and Ge7Sb93 phase-change films, a large increase in crystallization temperature is found when using a polycarbonate substrate instead of

  8. Epitaxial Fe16N2 thin film on nonmagnetic seed layer

    Science.gov (United States)

    Hang, Xudong; Zhang, Xiaowei; Ma, Bin; Lauter, Valeria; Wang, Jian-Ping

    2018-05-01

    Metastable α″ -Fe16N2 has attracted much interest as a candidate for rare-earth-free hard magnetic materials. We demonstrate that Fe16N2 thin films were grown epitaxially on Cr seed layers with MgO (001) substrates by facing-target sputtering. Good crystallinity with the epitaxial relation MgO (001 )[110 ] ∥ Cr (001 )[100 ] ∥ Fe16N2 (001 )[100 ] was obtained. The chemical order parameter, which quantifies the degree of N ordering in the Fe16N2 (the N-disordered phase is α' -Fe8N martensite), reaches 0.75 for Cr-seeded samples. Cr has a perfect lattice constant match with Fe16N2, and no noticeable strain can be assigned to Fe16N2. The intrinsic saturation magnetization of this non-strained Fe16N2 thin film at room temperature is determined to be 2.31 T by polarized neutron reflectometry and confirmed with vibrating sample magnetometry. Our work provides a platform to directly study the magnetic properties of high purity Fe16N2 films with a high order parameter.

  9. Nano Size Crystals of Geothite, alpha-FeOOH: Synthesis and Thermal Transformation

    Energy Technology Data Exchange (ETDEWEB)

    Christensen,A.; Jensen, T.; Bahl, C.; DiMasi, E.

    2007-01-01

    An aqueous suspension of amorphous iron(III) hydroxide was kept at room temperature (298 K) for 23 years. During this period of time the pH of the liquid phase changed from 4.3 to 2.85, and nano size crystals of goethite, {alpha}-FeOOH crystallized from the amorphous iron(III) hydroxide. Transmission electron microscopy (TEM) investigations, Moessbauer spectra, and powder X-ray diffraction using Co K{alpha} radiation showed that the only iron containing crystalline phase present in the recovered product was {alpha}-FeOOH. The size of these nano particles range from 10 to 100 nm measured by TEM. The thermal decomposition of {alpha}-FeOOH was investigated by time-resolved in situ synchrotron radiation powder X-ray diffraction and the data showed that the sample of {alpha}-FeOOH transformed to {alpha}-Fe{sub 2}O{sub 3} in the temperature range 444--584 K. A quantitative phase analysis shows the increase in scattered X-ray intensity from {alpha}-Fe{sub 2}O{sub 3} to follow the decrease of intensity from {alpha}-FeOOH in agreement with the topotactic phase transition.

  10. The Effect of Thickness on the Physical Properties of Fe2O3 Thin Films Prepared by DC Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    Baha'a A. Al-Hilli

    2017-11-01

    Full Text Available The objective of this study is to assess the influence of nano-particle Fe2O3 thin film thickness on some physical properties which were prepared by magnetron DC- sputtering on glass substrate at room temperature. The structure was tested with X-Ray diffraction and it was to be amorphous and to become single crystal with recognized peak in (003 after annealing at temperature 500oC. The physical properties as a function of deposition parameters and then film thickness were studied. The optical properties such as absorbance, energy gap and some optical constants are measured and found that of about (3eV energy gap.

  11. Hyperfine interaction studies and magnetic properties of FeCoAlN nanocomposite films

    International Nuclear Information System (INIS)

    Lancok, A.; Zaveta, K.; Kanuch, T.; Miglierini, M.; Lancok, J.; Postava, K.; Kohout, J.; Zivotsky, O.; Fendrych, F.

    2008-01-01

    Nanogranular magnetic films were produced by specially designed UHV plasma-jet system with DC hollow-cathode discharge. We investigated the properties of these ferromagnetic FeCoAlN-based films. The analyses of the samples were additionally complemented by the study of nuclear magnetic resonance (NMR), Moessbauer spectroscopy, magnetic measurements, and X-ray diffraction.

  12. Engineering Gilbert damping by dilute Gd doping in soft magnetic Fe thin Films

    NARCIS (Netherlands)

    Zhang, W.; Jiang, S.; Wong, P.K.J.; Sun, Li; Wang, Y.K.; Wang, Kai; de Jong, Machiel Pieter; van der Wiel, Wilfred Gerard; van der Laan, G.; Zhai, Y.

    2014-01-01

    By analyzing the ferromagnetic resonance linewidth, we show that the Gilbert damping constant in soft magnetic Fe thin films can be enhanced by ∼6 times with Gd doping of up to 20%. At the same time, the magnetic easy axis remains in the film plane while the coercivity is strongly reduced after Gd

  13. Theoretical investigation of electronic, magnetic and optical properties of Fe doped GaN thin films

    International Nuclear Information System (INIS)

    Salmani, E.; Mounkachi, O.; Ez-Zahraouy, H.; Benyoussef, A.; Hamedoun, M.; Hlil, E.K.

    2013-01-01

    Highlights: •Magnetic and optical properties Fe-doped GaN thin films are studied using DFT. •The band gaps of GaN thin films are larger than the one of the bulk. •The layer thickness and acceptor defect can switch the magnetic ordering. -- Abstract: Using first principles calculations based on spin-polarized density functional theory, the magnetic and optical properties of GaN and Fe-doped GaN thin films with and without acceptor defect is studied. The band structure calculations show that the band gaps of GaN thin films with 2, 4 and 6 layers are larger than the one of the bulk with wurtzite structure and decreases with increasing the film thickness. In Fe doped GaN thin films, we show that layer of thickness and acceptor defect can switch the magnetic ordering from disorder local moment (DLM) to ferromagnetic (FM) order. Without acceptor defect Fe doped GaN exhibits spin glass phase in 4 layers form and ferromagnetic state for 2 layers form of the thin films, while it exhibits ferromagnetic phase with acceptor defect such as vacancies defect for 2 and 4 layers. In the FM ordering, the thin films is half-metallic and is therefore ideal for spin application. The different energy between ferromagnetic state and disorder local moment state was evaluated. Moreover, the optical absorption spectra obtained by ab initio calculations confirm the ferromagnetic stability based on the charge state of magnetic impurities

  14. Ternary NiFeX as soft biasing film in a magnetoresistive sensor

    Science.gov (United States)

    Chen, Mao-Min; Gharsallah, Neila; Gorman, Grace L.; Latimer, Jacquie

    1991-04-01

    The properties of NiFeX ternary films (X being Al, Au, Nb, Pd, Pt, Si, and Zr) have been studied for soft-film biasing of the magnetoresistive (MR) trilayer sensor. In general, the addition of the element X into the NiFe alloy film decreases the saturation magnetization Bs and magnetoresistance coefficient of the film, while increasing the film's electrical resistivity ρ. One of the desirable properties of a soft film for biasing is high sheet resistance for minimum current flow. A figure of merit Bsρ that takes into account both the rate of increase in Bs and the rate of decrease in ρ when adding X element was derived to compare the effectiveness of various X elements in reducing the current shunting through the soft-film layer. Using this criterion, NiFeNb and NiFeZr emerge as good soft-film materials having a maximum sheet resistance relative to the MR layer. Other critical properties such as magnetoresistance coefficient, magnetostriction, coercivity, and anisotropy field were also examined and are discussed in this paper.

  15. Analysis of deuterium in V-Fe5at.% film by atom probe tomography (APT)

    KAUST Repository

    Gemma, Ryota; Al-Kassab, Talaat; Kirchheim, Reiner; Pundt, Astrid A.

    2011-01-01

    V-Fe5at.% 2 and 10-nm thick single layered films were prepared by ion beam sputtering on W substrate. They were loaded with D from gas phase at 0.2 Pa and at 1 Pa, respectively. Both lateral and depth D distribution of these films was investigated

  16. The evaluation of Young's modulus and residual stress of Cu films by NiFe/Cu bilayer film microbridge tests

    International Nuclear Information System (INIS)

    Zhou Zhimin; Zhou Yong; Cao Ying; Ding Wen; Mao Haiping

    2008-01-01

    This paper proposes a method to estimate the thickness limit for single-layer microbridge tests and also the thickness limit of one film on another film with known thickness for bilayer microbridge tests. To evaluate the mechanical properties of the Cu film, which could not be measured by single-layer microbridge tests, the NiFe single-layer film and NiFe/Cu bilayer film on silicon substrate are fabricated onto the microbridge by the MEMS technique. A load–deflection experiment is conducted upon the ceramic shaft adhered to the microbridge center by means of the XP nanoindenter system. From single-layer microbridge theory, Young's modulus and the residual stress of the NiFe film are deduced to be 192.74 ± 8.10 GPa and 287.75 ± 16.18 MPa, respectively. The data are introduced into bilayer microbridge theory and Young's modulus and the residual stress of the copper film are calculated to be 118.71 ± 6.54 GPa and 41.34 ± 4.42 MPa, respectively. The experimental results correspond well with those of nanoindentation

  17. Temperature dependent magnetic coupling between ferromagnetic FeTaC layers in multilayer thin films

    International Nuclear Information System (INIS)

    Singh, Akhilesh Kumar; Hsu, Jen-Hwa; Perumal, Alagarsamy

    2016-01-01

    We report systematic investigations on temperature dependent magnetic coupling between ferromagnetic FeTaC layers and resulting magnetic properties of multilayer structured [FeTaC (~67 nm)/Ta(x nm)] 2 /FeTaC(~67 nm)] thin films, which are fabricated directly on thermally oxidized Si substrate. As-deposited amorphous films are post annealed at different annealing temperatures (T A =200, 300 and 400 °C). Structural analyzes reveal that the films annealed at T A ≤200 °C exhibit amorphous nature, while the films annealed above 200 °C show nucleation of nanocrystals at T A =300 °C and well-defined α-Fe nanocrystals with size of about 9 nm in amorphous matrix for 400 °C annealed films. Room temperature and temperature dependent magnetic hysteresis (M–H) loops reveal that magnetization reversal behaviors and magnetic properties are strongly depending on spacer layer thickness (x), T A and temperature. A large reduction in coercivity (H C ) was observed for the films annealed at 200 °C and correlated to relaxation of stress quenched in during the film deposition. On the other hand, the films annealed at 300 °C exhibit unusual variation of H C (T), i.e., a broad minimum in H C (T) vs T curve. This is caused by change in magnetic coupling between ferromagnetic layers having different microstructure. In addition, the broad minimum in the H C (T) curve shifts from 150 K for x=1 film to 80 K for x=4 film. High-temperature thermomagnetization data show a strong (significant) variation of Curie temperature (T C ) with T A (x). The multilayer films annealed at 200 °C exhibit low value of T C with a minimum of 350 K for x=4 film. But, the films annealed at 400 °C show largest T C with a maximum of 869 K for x=1 film. The observed results are discussed on the basis of variations in magnetic couplings between FeTaC layers, which are majorly driven by temperature, spacer layer thickness, annealing temperature and nature of interfaces. - Highlights: • Preparation and

  18. Interaction domains in high performance NdFeB thick films

    Energy Technology Data Exchange (ETDEWEB)

    Woodcock, Tom; Khlopkov, Kirill; Schultz, Ludwig; Gutfleisch, Oliver [IFW Dresden, IMW, Dresden (Germany); Walther, Arno [Insitut Neel, CNRS-UJF, Grenoble (France); CEA Leti - MINATEC, Grenoble (France); Dempsey, Nora; Givord, Dominique [Insitut Neel, CNRS-UJF, Grenoble (France)

    2009-07-01

    Thick sputtered films (5-300 micron) of NdFeB have excellent hard magnetic properties which make them attractive for applications in micro-electro-mechanical systems (MEMS). A two step process consisting of triode sputtering and high temperature annealing produced films with energy densities approaching those of sintered NdFeB magnets. Magnetic force microscopy (MFM) using hard magnetic tips showed that the films deposited without substrate heating and at 300 C exhibited magnetic domains typical of low anisotropy materials. These films were amorphous in the as-deposited state. The film deposited at 500 C was crystalline and displaid hard magnetic properties. This was reflected in the magnetic microstructure which showed interaction domains typical of highly textured and high magnetic anisotropy materials with a grain size below or equal to the critical single-domain particle limit. With increasing substrate temperature, the domain patterns of the annealed films became coarser, indicating higher degrees of texture.

  19. Double switching hysteresis loop in a single layer Fe3Pt alloy thin films

    International Nuclear Information System (INIS)

    Nahid, M.A.I.; Suzuki, Takao

    2008-01-01

    The Fe 3 Pt alloy thin films were epitaxially grown on MgO(100) substrate by e-beam evaporation. The films were partially ordered at the substrate deposition temperature above 350 deg. C. These partially ordered films exhibit very large biaxial magnetic anisotropy constant in the order of 10 5 J/m 3 and produce double switching in the hysteresis loops. The difference of the switching field of these films can be up to about 3 x 10 5 A/m by tuning the angle of the applied field with respect to the easy axes. This double switching behavior stems from the large biaxial magnetic anisotropy of the films

  20. Residual stress change by thermal annealing in amorphous Sm-Fe-B thin films

    International Nuclear Information System (INIS)

    Na, S.M.; Suh, S.J.; Kim, H.J.; Lim, S.H.

    2002-01-01

    The change in the residual stress and its effect on mechanical bending and magnetic properties of sputtered amorphous Sm-Fe-B thin films are investigated as a function of annealing temperature. Two stress components of intrinsic compressive stress and tensile stress due to the difference of the thermal expansion coefficients between the substrate and thin film are used to explain the stress state in as-deposited thin films, and the annealing temperature dependence of residual stress, mechanical bending and magnetic properties

  1. Structural features of epitaxial NiFe2O4 thin films grown on different substrates by direct liquid injection chemical vapor deposition

    Science.gov (United States)

    Datta, R.; Loukya, B.; Li, N.; Gupta, A.

    2012-04-01

    NiFe2O4 (NFO) thin films are grown on four different substrates, i.e., Lead Zinc Niobate-Lead Titanate (PZN-PT), Lead Magnesium Niobate-Lead Titanate (PMN-PT), MgAl2O4 (MAO) and SrTiO3 (STO), by a direct liquid injection chemical vapor deposition technique (DLI-CVD) under optimum growth conditions where relatively high growth rate (˜20 nm/min), smooth surface morphology and high saturation magnetization values in the range of 260-290 emu/ cm3 are obtained. The NFO films with correct stoichiometry (Ni:Fe=1:2) grow epitaxially on all four substrates, as confirmed by energy dispersive X-ray spectroscopy, transmission electron microscopy and x-ray diffraction. While the films on PMN-PT and PZN-PT substrates are partially strained, essentially complete strain relaxation occurs for films grown on MAO and STO. The formations of threading dislocations along with dark diffused contrast areas related to antiphase domains having a different cation ordering are observed on all four substrates. These crystal defects are correlated with lattice mismatch between the film and substrate and result in changes in magnetic properties of the films. Atomic resolution HAADF imaging and EDX line profiles show formation of a sharp interface between the film and the substrate with no inter-diffusion of Pb or other elements across the interface. Antiphase domains are observed to originate at the film-substrate interface.

  2. Crystal growth, electronic structure, and properties of Ni-substituted FeGa{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Likhanov, Maxim S. [Department of Chemistry, Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Verchenko, Valeriy Yu. [Department of Chemistry, Lomonosov Moscow State University, Moscow 119991 (Russian Federation); National Institute of Chemical Physics and Biophysics, 12618 Tallinn (Estonia); Bykov, Mikhail A. [Department of Chemistry, Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Tsirlin, Alexander A. [National Institute of Chemical Physics and Biophysics, 12618 Tallinn (Estonia); Experimental Physics VI, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, 86135 Augsburg (Germany); Gippius, Andrei A. [Faculty of Physics, Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Shubnikov Institute of Crystallography, Russian Academy of Science, 119333, Moscow (Russian Federation); Berthebaud, David; Maignan, Antoine [Laboratoire CRISMAT, UMR 6508 CNRS/ENSICAEN, F-14050 CAEN Cedex 4 (France); Shevelkov, Andrei V., E-mail: shev@inorg.chem.msu.ru [Department of Chemistry, Lomonosov Moscow State University, Moscow 119991 (Russian Federation)

    2016-04-15

    Crystals of the Fe{sub 1−x}Ni{sub x}Ga{sub 3} limited solid solution (x<0.045) have been grown from gallium flux. We have explored the electronic structure as well as magnetic and thermoelectric properties of Fe{sub 0.975}Ni{sub 0.025}Ga{sub 3} in comparison with Fe{sub 0.95}Co{sub 0.05}Ga{sub 3}, following the rigid band approach and assuming that one Ni atom donates twice the number of electrons as one Co atom. However, important differences between the Co- and Ni-doped compounds are found below 620 K, which is the temperature of the metal-to-insulator transition for both compounds. We have found that Fe{sub 0.975}Ni{sub 0.025}Ga{sub 3} displays lower degree of spatial inhomogeneity on the local level and exhibits diamagnetic behavior with a broad shallow minimum in the magnetic susceptibility near 35 K, in sharp contrast with the Curie–Weiss paramagnetism of Fe{sub 0.95}Co{sub 0.05}Ga{sub 3}. Transport measurements have shown the maximum of the thermoelectric figure-of-merit ZT of 0.09 and 0.14 at 620 K for Fe{sub 0.975}Ni{sub 0.025}Ga{sub 3} and Fe{sub 0.95}Co{sub 0.05}Ga{sub 3}, respectively. - Graphical abstract: Crystals of Ni-substituted FeGa{sub 3} up to 8 mm long were grown from gallium flux (see Figure for the temperature profile and crystal shape) that allowed studying magnetic and thermoelectric properties of the title solid solution.

  3. Graphene derivatives/Fe_3O_4/polymer nanocomposite films: Optical and electrical properties

    International Nuclear Information System (INIS)

    Hatel, Rhizlane; Goumri, Meryem; Ratier, Bernard; Baitoul, Mimouna

    2017-01-01

    This paper reports a simple solution casting method for the preparation of nanocomposite films in which graphene oxide (GO)/Fe_3O_4 nanocomposites are incorporated into poly (vinyl alcohol) (PVA) matrix. The films obtained with different weight percent of GO/Fe_3O_4 (0.5, 0.7 and 1 wt%) are subjected an in situ chemical and thermal reduction in order to explore the evolution and interactions between these components under different treatments and get an insight into on how this can affects the optical and electrical properties of these nanocomposites. Characterization was carried out using, UV–Vis absorption, Photoluminescence, electrical conductivity measurements, Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. Strong covalent functionalization occurs between the polymer and graphene derivatives (GD)/Fe_3O_4 hybrids. The experimental results obtained for our nanocomposites films exhibit significant enhancement in properties highlighted the efficiency of the in situ thermal reduction. The high absorption with strong photoluminescence and electrical conductivity achieved might promote these nanocomposites for opto-electronic devices in near future. - Highlights: • Novel inorganic-organic hybrid flexible films were successfully prepared. • Good interfacial interaction between the graphene/Fe_3O_4 and the hydroxyl-rich PVA. • Optical and electrical properties of Graphene Derivatives/Fe_3O_4/PVA were investigated. • Thermally reduced GO/Fe_3O_4/PVA films show high absorption and strong photoluminescence.

  4. Magnetic properties of amorphous Tb-Fe thin films with an artificially layered structure

    International Nuclear Information System (INIS)

    Sato, N.

    1986-01-01

    An alternating terbium-iron (Tb-Fe) multilayer structure artificially made in amorphous Tb-Fe thin films gives rise to excellent magnetic properties of large perpendicular uniaxial anisotropy, large saturation magnetization, and large coercivity over a wide range of Tb composition in the films. The films are superior to amorphous Tb-Fe alloy thin films, especially when they are piled up with a monatomic layer of Tb and several atomic layers of Fe in an alternating fashion. Small-angle x-ray diffraction analysis confirmed the layering of monatomic layers of Tb and Fe, where the periodicity of the layers was found to be about 5.9 A. Direct evidence for an artificially layered structure was obtained by transmission electron microscopic and Auger electron spectroscopic observations. Together with magnetic measurements of hysteresis loops and torque curves, it has been concluded that the most important origin of the large magnetic uniaxial anisotropy can be attributed to the Tb-Fe pairs aligned perpendicular to the films

  5. Chemical synthesis of Fe{sub 2}O{sub 3} thin films for supercapacitor application

    Energy Technology Data Exchange (ETDEWEB)

    Kulal, P.M.; Dubal, D.P.; Lokhande, C.D. [Holography and Material Research Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, M.S. (India); Fulari, V.J., E-mail: vijayfulari@gmail.com [Holography and Material Research Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, M.S. (India)

    2011-02-03

    Research highlights: > Simple chemical synthesis of Fe{sub 2}O{sub 3}. > Formation of amorphous and hydrous Fe{sub 2}O{sub 3}. > Potential candidate for supercapacitors. - Abstract: Fe{sub 2}O{sub 3} thin films have been prepared by novel chemical successive ionic layer adsorption and reaction (SILAR) method. Further these films were characterized for their structural, morphological and optical properties by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrum, scanning electron microscopy (SEM), wettability test and optical absorption studies. The XRD pattern showed that the Fe{sub 2}O{sub 3} films exhibit amorphous in nature. Formation of iron oxide compound was confirmed from FTIR studies. The optical absorption showed existence of direct optical band gap of energy 2.2 eV. Fe{sub 2}O{sub 3} film surface showed superhydrophilic nature with water contact angle less than 10{sup o}. The supercapacitive properties of Fe{sub 2}O{sub 3} thin film investigated in 1 M NaOH electrolyte showed supercapacitance of 178 F g{sup -1} at scan rate 5 mV/s.

  6. Soft magnetic properties of FeRuGaSi alloy films: SOFMAX

    International Nuclear Information System (INIS)

    Hayashi, K.; Hayakawa, M.; Ishikawa, W.; Ochiai, Y.; Iwasaki, Y.; Aso, K.

    1988-01-01

    To advance new soft magnetic materials of an FeGaSi alloy into the commercial world, improvements on various properties were designed by introducing additive elements without sacrificing its high saturation magnetic induction. The detailed studies on the diversified properties, such as saturation magnetic induction, film internal stress, wear resistivity, and so on, were performed. High-frequency permeability of the laminated structure film was also investigated. As a result, the Ru-added FeRuGaSi alloy films, whose typical compositions are Fe 72 Ru 4 Ga 7 Si 17 and Fe 68 Ru 8 Ga 7 Si 17 (at. %), prove to be excellent soft magnetic materials especially appropriate for the magnetic recording/playback head core use

  7. Preparation and properties of [(NdFeB)x/(Nb)z]n multi-layer films

    International Nuclear Information System (INIS)

    Tsai, J.-L.; Chin, T.-S.; Yao, Y.-D.; Melsheimer, A.; Fisher, S.; Drogen, T.; Kelsch, M.; Kronmueller, H.

    2003-01-01

    Multi-layer [(NdFeB) x /(Nb) z ] n films with 200 nm≥x≥10 nm, 10 nm≥z≥0, 40≥n≥2, prepared by ion beam sputtering and subsequent annealing, show significantly enhanced coercivity due to the reduced grain size that enhances the anisotropy of individual grains. After annealing at 630 deg. C, some Nd 2 Fe 14 B grains were enriched with Nb and isolated as the thickness of the Nb spacer layer increases. For multi-layer (NdFeB x /Nb z ) n films with 100 nm ≥x≥25 nm, 5 nm≥z≥2 nm, their coercivity and remanence ratio are better than that of a single NdFeB film. Up to 17.8 kOe room temperature coercivity has been obtained for a sample with x=25 nm, z=5 nm and n=16

  8. Structural and magnetic properties of Ni{sub 78}Fe{sub 22} thin films sandwiched between low-softening-point glasses and application in spin devices

    Energy Technology Data Exchange (ETDEWEB)

    Misawa, Takahiro; Mori, Sumito [Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan); Komine, Takashi [Faculty of Engineering, Ibaraki University, Hitachi, Ibaraki 316-8511 (Japan); Fujioka, Masaya; Nishii, Junji [Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan); Kaiju, Hideo, E-mail: kaiju@es.hokudai.ac.jp [Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan)

    2016-12-30

    Graphical abstract: This paper presents the first demonstration of the formation of Ni{sub 78}Fe{sub 22} thin films sandwiched between low-softening-point (LSP) glasses used in spin quantum cross (SQC) devices and the theoretical prediction of spin filter effect in Ni{sub 78}Fe{sub 22}-based SQC devices. The fomation of the LSP-glass/Ni{sub 78}Fe{sub 22}/LSP-glass structures was successfully demonstrated using a newly proposed thermal pressing technique. Interestingly, this technique gives rise to both a highly-oriented crystal growth in Ni{sub 78}Fe{sub 22} thin films and a 100-fold enhancement in coercivity, in contrast to those of as-deposited Ni{sub 78}Fe{sub 22} thin films. This remarkable increase in coercivity can be explained by the calculation based on two-dimensional random anisotropy model. These excellent features on structural and magnetic properties allowed us to achieve that the stray magnetic field was uniformly generated from the Ni{sub 78}Fe{sub 22} thin-film edge in the direction perpendicular to the cross section of the LSP-glass/Ni{sub 78}Fe{sub 22}/LSP-glass structures. As we calculated the stray magnetic field generated between the two edges of Ni{sub 78}Fe{sub 22} thin-film electrodes in SQC devices, a high stray field of approximately 5 kOe was generated when the gap distance between two edges of the Ni{sub 78}Fe{sub 22} thin-film electrodes was less than 5 nm and the thickness of Ni{sub 78}Fe{sub 22} was greater than 20 nm. These experimental and calculated results suggest that Ni{sub 78}Fe{sub 22} thin films sandwiched between LSP glasses can be used as electrodes in SQC devices, providing a spin-filter effect, and also our proposed techniques utilizing magnetic thin-film edges will open up new opportunities for the creation of high performance spin devices, such as large magnetoresistance devices and nanoscale spin injectors. Our paper is of strong interest to the broad audience of Applied Surface Science, as it demonstrates that the

  9. 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.

  10. Synthesis crystal stuctrure and thermoelectric properties of the ternary skutterudite Fe2Pd2Sb12

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Jiří; Laufek, F.; Plecháček, T.; Plášil, J.

    2010-01-01

    Roč. 493, 1-2 (2010), s. 50-54 ISSN 0925-8388 R&D Projects: GA ČR GA203/07/0267 Institutional research plan: CEZ:AV0Z40500505 Keywords : Fe2Pd2Sb12 * crystal structure * skutterudite Subject RIV: CA - Inorganic Chemistry Impact factor: 2.138, year: 2010

  11. Passive Fe2+ : ZnSe single-crystal Q switch for 3-mu m lasers

    NARCIS (Netherlands)

    Voronov, AA; Kozlovskii, [No Value; Korostelin, YV; Podmar'kov, YP; Polushkin, VG; Frolov, MP

    Passive Q-switching of 3-mu m lasers with the help of a Fe2+ : ZnSe single crystal is demonstrated. The 6-mJ, 50-ns giant pulses are obtained from a 2.9364-mu m Er : YAG laser by using this passive Q switch.

  12. Synthesis, electronic transport and optical properties of Si:α-Fe2O3 single crystals

    NARCIS (Netherlands)

    Rettie, A.J.E.; Chemelewski, W.D.; Wygant, B.R.; Lindemuth, J.; Lin, J.F.; Eisenberg, D.; Brauer, C.S.; Johnson, T.J.; Beiswenger, T.N.; Ash, R.D.; Li, X.; Zhou, J.; Mullins, C.B.

    2016-01-01

    We report the synthesis of silicon-doped hematite (Si:alpha-Fe2O3) single crystals via chemical vapor transport, with Si incorporation on the order of 1019 cm(-3). The conductivity, Seebeck and Hall effect were measured in the basal plane between 200 and 400 K. Distinct differences in electron

  13. Epitaxial growth and characterization of CoO/Fe(001) thin film layered structures

    International Nuclear Information System (INIS)

    Brambilla, A.; Sessi, P.; Cantoni, M.; Duo, L.; Finazzi, M.; Ciccacci, F.

    2008-01-01

    By means of X-ray photoemission spectroscopy and low energy electron diffraction, we show that it is possible to grow good quality thin epitaxial CoO films on Fe(001) substrates, through deposition in oxygen atmosphere. In particular, the composition and the structure of CoO(001)/Fe(001) bilayer systems and Fe(001)/CoO(001)/Fe(001) trilayer systems have been investigated by monitoring the evolution of the chemical interactions at the interfaces as a function of CoO thickness and growth temperature. We observe the presence of Fe oxides at the CoO/Fe interface and of a thin layer of metallic cobalt at the upper Fe/CoO interface of trilayer systems

  14. Effect of argon ion etching on the magnetic properties of FeCoB films

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Junwei; Zhou, Kan; Yang, Yi; Tang, Dongming; Zhang, Baoshan, E-mail: malab@nju.edu.cn; Lu, Mu; Lu, Huaixian

    2015-01-15

    In this paper, a new method to modify Ta underlayers by an argon ion etching technology is introduced. Surface roughness of Ta underlayers, as well as soft magnetic properties of post-deposited FeCoB films can be improved by applying a proper ion etching process. The reduction of magnetic coercivity of FeCoB films deposited on the modified Ta underlayers is attributed to the improvement of interfacial roughness, which can reduce magnetic ripples in magnetic films. The microwave damping linewidth of magnetic films is also found to be related to the interfacial roughness. Ta underlayers modified by the ion etching can reduce the influence of two-magnon scattering effect, and thus tune microwave properties of magnetic films. All the results prove that argon ion etching is an effective way to tailor magnetic properties of magnetic films. - Highlights: • We believe that our method to tune the magnetic film properties will be interesting for general readers of Journal of Magnetism and Magnetic Materials. • In the paper, argon ion etching is applied to the Ta underlayer before the FeCoB film is deposited on it. • The modified interface roughness has effectively improved the magnetic properties, including the static magnetic and microwave performance. • The method is valuable for other underlayer/magnetic film systems.

  15. Raman Scattering in La0.2Sr0.8FeO3-δ thin film: annealing-induced reduction and phase transformation

    Science.gov (United States)

    Islam, Mohammad; Xie, Yujun; Scafetta, Mark; May, Steven; Spanier, Jonathan

    2015-03-01

    Raman scattering in thin film La0.2Sr0.8FeO3-δ on MgO(001) collected at 300 K following different stages of annealing at selected temperatures (300 K topotactic transformation of the crystal structure from that of the rhombohedral ABO3 perovskites to that of Brownmillerite-like structure consisting of octahedrally and tetrahedrally coordinated Fe atoms. We acknowledge the ONR (N00014-11-1-0664), the Drexel Centralized Research Facilities, the Army Research Office DURIP program, the Department of Education (GAANN-RETAIN, Award No. P200A100117), and Leszek Wielunski at Rutgers University.

  16. Ferromagnetic resonance linewidth and two-magnon scattering in Fe1-xGdx thin films

    Directory of Open Access Journals (Sweden)

    Sheng Jiang

    2017-05-01

    Full Text Available Magnetization dynamics of Fe1-xGdx thin films (0 ≤ x ≤ 22% has been investigated by ferromagnetic resonance (FMR. Out-of-plane magnetic field orientation dependence of resonance field and linewidth has been measured. Resonance field and FMR linewidth have been fitted by the free energy of our system and Landau-Lifshitz-Gilbert (LLG equation. It is found that FMR linewidth contains huge extrinsic components including two-magnon scattering contribution and inhomogeneous broadening for FeGd alloy thin films. In addition, the intrinsic linewidth and real damping constants have been obtained by extracting the extrinsic linewidth. The damping constant enhanced from 0.011 to 0.038 as Gd dopants increase from 0 to 22% which originates from the enhancement of L-S coupling in FeGd thin films. Besides, gyromagnetic ratio, Landé factor g and magnetic anisotropy of our films have also been determined.

  17. Growth and surface modification of LaFeO3 thin films induced by reductive annealing

    International Nuclear Information System (INIS)

    Flynn, Brendan T.; Zhang, Kelvin H.L.; Shutthanandan, Vaithiyalingam; Varga, Tamas; Colby, Robert J.; Oleksak, Richard P.; Manandhar, Sandeep; Engelhard, Mark H.; Chambers, Scott A.; Henderson, Michael A.; Herman, Gregory S.; Thevuthasan, Suntharampillai

    2015-01-01

    Highlights: • LaFeO 3 was grown by molecular beam epitaxy on ZrO 2 :Y 2 O 3 . • The film was highly oriented but not single crystalline. • Angle resolved XPS revealed differences between surface and bulk oxygen. • Annealing the film in vacuum resulted in the sequential reduction of Fe cations. • A greater degree of Fe reduction was found at the surface. - Abstract: The mixed electronic and ionic conductivity of perovskite oxides has enabled their use in diverse applications such as automotive exhaust catalysts, solid oxide fuel cell cathodes, and visible light photocatalysts. The redox chemistry at the surface of perovskite oxides is largely dependent on the oxidation state of the metal cations as well as the oxide surface stoichiometry. In this study, LaFeO 3 (LFO) thin films grown on yttria-stabilized zirconia (YSZ) was characterized using both bulk and surface sensitive techniques. A combination of in situ reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD), and Rutherford backscattering spectrometry (RBS) demonstrated that the film is primarily textured in the [1 0 0] direction and is stoichiometric. High-resolution transmission electron microscopy measurements show regions that are dominated by [1 0 0] oriented LFO grains that are oriented with respect to the substrates lattice. However, selected regions of the film show multiple domains of grains that are not [1 0 0] oriented. The film was annealed in an ultra-high vacuum chamber to simulate reducing conditions and studied by angle-resolved X-ray photoelectron spectroscopy (XPS). Iron was found to exist as Fe(0), Fe(II), and Fe(III) depending on the annealing conditions and the depth within the film. A decrease in the concentration of surface oxygen species was correlated with iron reduction. These results should help guide and enhance the design of LFO materials for catalytic applications

  18. Magnetic phase transitions and large mass enhancement in single crystal CaFe4As3

    International Nuclear Information System (INIS)

    Zhang Xiao-Dong; Wu Wei; Zheng Ping; Wang Nan-Lin; Luo Jian-Lin

    2012-01-01

    High quality single crystal CaFe 4 As 3 was grown by using the Sn flux method. Unlike layered CaFe 2 As 2 , CaFe 4 As 3 crystallizes in an orthorhombic three-dimensional structure. Two magnetic ordering transitions are observed at ∼ 90 K and ∼ 27 K, respectively. The high temperature transition is an antiferromagnetic(AF) ordering transition. However, the low temperature transition shows complex properties. It shows a ferromagnetic-like transition when a field is applied along b-axis, while antiferromagnetism-like transition when a field is applied perpendicular to b-axis. These results suggest that the low temperature transition at 27 K is a first-order transition from an AF state to a canted AF state. In addition, the low temperature electron specific heat coefficient reaches as high as 143 mJ/mol·K 2 , showing a heavy fermion behavior. (rapid communication)

  19. Ab-initio study of the interfacial properties in ultrathin MgO films on O-rich FeO/Fe(001) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Junjin; Yu, Byungdeok [University of Seoul, Seoul (Korea, Republic of)

    2014-09-15

    Using ab-initio simulations based on density functional theory, we systematically studied the interfacial properties of MgO films on O-rich FeO/Fe(001) surfaces with increasing number of MgO layers from one to three monolayers (MLs). The structural and the adhesion properties of the MgO/FeO/Fe(001) system were assessed and compared with those of simple MgO/Fe(001) interfaces. Our calculated results showed that the adhesion energy for MgO/FeO/Fe(001) was smaller than that for simple MgO/Fe(001). An analysis of the electronic structures and the charge rearrangements of the MgO/FeO/Fe(001) interfaces was also performed. The work functions of the MgO/FeO/Fe(001) systems upon the deposition of MgO films exhibited smaller decreases (0.45 - 0.67 eV) than those (1.43 - 1.74 eV) of the MgO/Fe(001) systems. In addition, the obtained work functions (3.77 - 3.99 eV) for MgO/FeO/Fe(001) were much larger than those (2.12 - 2.43 eV) for MgO/Fe(001).

  20. Microstructure and Magnetic Properties of NdFeB Films through Nd Surface Diffusion Process

    Directory of Open Access Journals (Sweden)

    Wenfeng Liu

    2017-01-01

    Full Text Available Ta/Nd/NdFeB/Nd/Ta films were deposited by magnetron sputtering on Si (100 substrates and subsequently annealed for 30 min at 923 K in vacuum. It was found that the microstructure and magnetic properties of Ta/Nd/NdFeB/Nd/Ta films strongly depend on the NdFeB layer thickness. With NdFeB layer thickness increasing, both the grain size and the strain firstly reduce and then increase. When NdFeB layer thickness is 750 nm, the strain reaches the minimum value. Meanwhile, both the in-plane and perpendicular coercivities firstly drastically increase and then slowly decrease with NdFeB layer thickness increasing. The highest in-plane and perpendicular coercivities can be obtained at NdFeB layer thickness of 750 nm, which are 21.2 kOe and 19.5 kOe, respectively. In addition, the high remanence ratio (remanent magnetization/saturation magnetization of 0.87 can also be achieved in Ta/Nd/NdFeB (750 nm/Nd/Ta film.

  1. Artificially controlled stress anisotropy and magnetic properties of FeTaN thin films

    International Nuclear Information System (INIS)

    Deng, H.; Jarratt, J.D.; Minor, M.K.; Barnard, J.A.

    1997-01-01

    This article presents a new method of investigating internal stress effects on thin film magnetic properties, in this case magnetically soft FeTaN sputtered films. The FeTaN films were deposited on a series of oxidized silicon (111) substrates prestressed to different degrees. During sputtering all the deposition conditions were kept exactly the same for all the samples. However, anisotropic stresses with different amplitudes are systematically introduced into the films when the prestressed wafers were released. In this way, FeTaN films with compressive stress varying from 80 to 608 MPa are produced. We found that the saturation magnetostriction (λ s ), anisotropy field (H k ), initial permeability (μ i ) as well as easy axis orientation of FeTaN thin films are strongly affected by the induced stress anisotropy. A stress ratio concept is proposed as a measure of the degree of the stress anisotropy. Models for easy-hard axis switching induced by stress for magnetic films with positive magnetostriction are discussed. copyright 1997 American Institute of Physics

  2. Self-Poling of BiFeO3 Thick Films.

    Science.gov (United States)

    Khomyakova, Evgeniya; Sadl, Matej; Ursic, Hana; Daniels, John; Malic, Barbara; Bencan, Andreja; Damjanovic, Dragan; Rojac, Tadej

    2016-08-03

    Bismuth ferrite (BiFeO3) is difficult to pole because of the combination of its high coercive field and high electrical conductivity. This problem is particularly pronounced in thick films. The poling, however, must be performed to achieve a large macroscopic piezoelectric response. This study presents evidence of a prominent and reproducible self-poling effect in few-tens-of-micrometer-thick BiFeO3 films. Direct and converse piezoelectric measurements confirmed that the as-sintered BiFeO3 thick films yield d33 values of up to ∼20 pC/N. It was observed that a significant self-poling effect only appears in cases when the films are heated and cooled through the ferroelectric-paraelectric phase transition (Curie temperature TC ∼ 820 °C). These self-poled films exhibit a microstructure with randomly oriented columnar grains. The presence of a compressive strain gradient across the film thickness cooled from above the TC was experimentally confirmed and is suggested to be responsible for the self-poling effect. Finally, the macroscopic d33 response of the self-poled BiFeO3 film was characterized as a function of the driving-field frequency and amplitude.

  3. On stoichiometry and intermixing at the spinel/perovskite interface in CoFe2O4/BaTiO3 thin films.

    Science.gov (United States)

    Tileli, Vasiliki; Duchamp, Martial; Axelsson, Anna-Karin; Valant, Matjaz; Dunin-Borkowski, Rafal E; Alford, Neil McN

    2015-01-07

    The performance of complex oxide heterostructures depends primarily on the interfacial coupling of the two component structures. This interface character inherently varies with the synthesis method and conditions used since even small composition variations can alter the electronic, ferroelectric, or magnetic functional properties of the system. The focus of this article is placed on the interface character of a pulsed laser deposited CoFe2O4/BaTiO3 thin film. Using a range of state-of-the-art transmission electron microscopy methodologies, the roles of substrate morphology, interface stoichiometry, and cation intermixing are determined on the atomic level. The results reveal a surprisingly uneven BaTiO3 substrate surface formed after the film deposition and Fe atom incorporation in the top few monolayers inside the unit cell of the BaTiO3 crystal. Towards the CoFe2O4 side, a disordered region extending several nanometers from the interface was revealed and both Ba and Ti from the substrate were found to diffuse into the spinel layer. The analysis also shows that within this somehow incompatible composite interface, a different phase is formed corresponding to the compound Ba2Fe3Ti5O15, which belongs to the ilmenite crystal structure of FeTiO3 type. The results suggest a chemical activity between these two oxides, which could lead to the synthesis of complex engineered interfaces.

  4. Corrosion resistance of sintered NdFeB coated with SiC/Al bilayer thin films by magnetron sputtering

    International Nuclear Information System (INIS)

    Huang, Yiqin; Li, Heqin; Zuo, Min; Tao, Lei; Wang, Wei; Zhang, Jing; Tang, Qiong; Bai, Peiwen

    2016-01-01

    The poor corrosion resistance of sintered NdFeB imposes a great challenge in industrial applications. In this work, the SiC/Al bilayer thin films with the thickness of 510 nm were deposited on sintered NdFeB by magnetron sputtering to improve the corrosion resistance. A 100 nm Al buffer film was used to reduce the internal stress between SiC and NdFeB and improve the surface roughness of the SiC thin film. The morphologies and structures of SiC/Al bilayer thin films and SiC monolayer film were investigated with FESEM, AFM and X-ray diffraction. The corrosion behaviors of sintered NdFeB coated with SiC monolayer film and SiC/Al bilayer thin films were analyzed by polarization curves. The magnetic properties were measured with an ultra-high coercivity permanent magnet pulse tester. The results show that the surface of SiC/Al bilayer thin films is more compact and uniform than that of SiC monolayer film. The corrosion current densities of SiC/Al bilayer films coated on NdFeB in acid, alkali and salt solutions are much lower than that of SiC monolayer film. The SiC/Al bilayer thin films have little influence to the magnetic properties of NdFeB. - Highlights: • The same thick Al, SiC and SiC/Al films are deposited on NdFeB by magnetron sputtering. • 510 nm SiC/Al bilayer films can improve the corrosion resistance of the NdFeB evidently. • Al buffer layer improves effectively the surface roughness of the SiC thin film. • SiC/Al bilayer films do not deteriorate the magnetic properties of NdFeB.

  5. Corrosion resistance of sintered NdFeB coated with SiC/Al bilayer thin films by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yiqin [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Li, Heqin, E-mail: lhqjs@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zuo, Min; Tao, Lei; Wang, Wei [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zhang, Jing; Tang, Qiong [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei 230009 (China); Bai, Peiwen [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China)

    2016-07-01

    The poor corrosion resistance of sintered NdFeB imposes a great challenge in industrial applications. In this work, the SiC/Al bilayer thin films with the thickness of 510 nm were deposited on sintered NdFeB by magnetron sputtering to improve the corrosion resistance. A 100 nm Al buffer film was used to reduce the internal stress between SiC and NdFeB and improve the surface roughness of the SiC thin film. The morphologies and structures of SiC/Al bilayer thin films and SiC monolayer film were investigated with FESEM, AFM and X-ray diffraction. The corrosion behaviors of sintered NdFeB coated with SiC monolayer film and SiC/Al bilayer thin films were analyzed by polarization curves. The magnetic properties were measured with an ultra-high coercivity permanent magnet pulse tester. The results show that the surface of SiC/Al bilayer thin films is more compact and uniform than that of SiC monolayer film. The corrosion current densities of SiC/Al bilayer films coated on NdFeB in acid, alkali and salt solutions are much lower than that of SiC monolayer film. The SiC/Al bilayer thin films have little influence to the magnetic properties of NdFeB. - Highlights: • The same thick Al, SiC and SiC/Al films are deposited on NdFeB by magnetron sputtering. • 510 nm SiC/Al bilayer films can improve the corrosion resistance of the NdFeB evidently. • Al buffer layer improves effectively the surface roughness of the SiC thin film. • SiC/Al bilayer films do not deteriorate the magnetic properties of NdFeB.

  6. Investigation of electronic states of infinite-layer SrFeO{sub 2} epitaxial thin films by X-ray photoemission and absorption spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Chikamatsu, Akira, E-mail: chikamatsu@chem.s.u-tokyo.ac.jp [Department of Chemistry, University of Tokyo, Tokyo 113-0033 (Japan); Matsuyama, Toshiya [Department of Chemistry, University of Tokyo, Tokyo 113-0033 (Japan); Hirose, Yasushi [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan); Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan); Kumigashira, Hiroshi; Oshima, Masaharu [Department of Applied Chemistry, University of Tokyo, Tokyo 113-8656 (Japan); Hasegawa, Tetsuya [Department of Chemistry, University of Tokyo, Tokyo 113-0033 (Japan); Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Electronic states of infinite-layer SrFeO{sub 2} films have been experimentally observed. Black-Right-Pointing-Pointer Fe 3d states have higher densities of states in the valence-band region. Black-Right-Pointing-Pointer Three peaks derived from Fe 3d states were observed in the conduction-band region. Black-Right-Pointing-Pointer Indirect bandgap value was determined to be 1.3 eV. - Abstract: We investigated the electronic states of a single-crystal SrFeO{sub 2} epitaxial thin film in the valence-band and conduction-band regions using synchrotron-radiation X-ray photoemission and absorption spectroscopies. Fe 2p-3d resonant photoemission measurements revealed that the Fe 3d states have higher densities of states at binding energies of 3-5 eV and 5-8.5 eV in the valence-band region. The O K-edge X-ray absorption spectrum exhibited three peaks in the Fe 3d-derived conduction band hybridized with O 2p states; these can be assigned to Fe 3d{sub xy}, 3d{sub xz} + 3d{sub yz}, and 3d{sub x}{sup 2}{sub -y}{sup 2}. In addition, the indirect bandgap value of the SrFeO{sub 2} film was determined to be 1.3 eV by transmission and absorption spectroscopies.

  7. Modulated magnetic structure of an inhomogeneous stressed single crystal FeBO3

    International Nuclear Information System (INIS)

    Sharipiv, M.Z.; Dzhuraev, D.R.; Sokolov, B.Yu.; Kurbanov, M.

    2010-01-01

    With the help of low-symmetry mechanical stresses, we induced an additional spatially inhomogeneous anisotropy in the basal plane of a single crystal FeBO 3 . By the magnetooptical method, we study the effect of an inhomogeneous magnetic anisotropy on the magnetic state of this easy-plane weak ferromagnetic. It is established that, at the magnetization of inhomogeneously stressed FeBO 3 in the basal plane near some separated direction, the crystal transits from the homogeneous state into a spatially modulated magnetic state. The latter can be represented in the form of a static spin wave, in which a local vector of ferromagnetism oscillates near the direction of the mean magnetization of a crystal, by remaining in the basal plane.

  8. Structural, optical and electrical properties of Cu{sub 2}FeSnX{sub 4} (X = S, Se) thin films prepared by chemical spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Khadka, Dhruba B.; Kim, JunHo, E-mail: jhk@inu.ac.kr

    2015-07-25

    Highlights: • CFTS(Se) thin films have been synthesized by low-cost spray-based deposition. • The fabricated films were found to be of stannite structure and p-type conductivity. • Band gaps of CFTS and CFTSe thin films are 1.37 and 1.11 eV, respectively. - Abstract: We report on fabrication of polycrystalline Cu{sub 2}FeSnX{sub 4} (X = S, Se) thin films by chemical spray pyrolysis subsequent with post-sulfurization and selenization. The post-annealing of as-sprayed Cu{sub 2}FeSnS{sub 4} (CFTS) films in sulfur and selenium ambient demonstrated drastically improved surface texture as well as crystallinity. The crystal lattice parameters calculated from X-ray diffraction patterns for post-annealed films were found to be consistent with stannite structure. The fabricated Cu{sub 2}FeSnS{sub 4} (CFTS) and Cu{sub 2}FeSnSe{sub 4} (CFTSe) films showed p-type conductivity with carrier concentration in the range of 10{sup 21} cm{sup −3} and mobility ∼1–5 cm{sup 2} V{sup −1} s{sup −1}. The band gap energies of post-sulfurized CFTS and post-selenized CFTSe films were estimated to be ∼1.37 eV and ∼1.11 eV with an error of ±0.02 eV by UV–Vis absorption, respectively, which are promising for photovoltaic application.

  9. Effect of crystal structure on optical properties of sol–gel derived zirconia thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaodong, E-mail: xiaodong_wang@tongji.edu.cn [Pohl Institute of Solid State Physics, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Tongji University, Shanghai 200092 (China); Wu, Guangming; Zhou, Bin [Pohl Institute of Solid State Physics, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Tongji University, Shanghai 200092 (China); Shen, Jun, E-mail: shenjun67@tongji.edu.cn [Pohl Institute of Solid State Physics, Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Tongji University, Shanghai 200092 (China)

    2013-04-15

    Highlights: ► ZrO{sub 2} films were deposited by sol–gel method. ► Crystal structures of the films were tuned by different thermal annealing methods. ► The refractive indices vary with the crystal structures of the films. ► Lattice-mismatch was found to reduce the refractive index of ZrO{sub 2} films. -- Abstract: The optical properties of sol–gel derived zirconia thin films and their relation to the crystal structure are studied in this paper. ZrO{sub 2} films were deposited on quartz glass and silicon wafer substrates by sol–gel method with conventional furnace annealing (CFA) and rapid thermal annealing (RTA). Crystal structures of the films were analyzed by X-ray diffraction (XRD) and Raman spectroscopy, while refractive indices of the films were determined from the reflectance and transmittance spectra. The refractive indices vary with the function of crystal structure and density of the films, which depends on annealing temperature and annealing technique. Lattice-mismatch between monoclinic phase and tetragonal phase was found to reduce the refractive index of ZrO{sub 2} films.

  10. Electronic structure of Cr doped Fe3O4 thin films by X-ray absorption near-edge structure spectroscopy

    Science.gov (United States)

    Chen, Chi-Liang; Dong, Chung-Li; Asokan, Kandasami; Chern, G.; Chang, C. L.

    2018-04-01

    Present study reports the electronic structures of Cr doped Fe3O4 (Fe3-xCrxO4 (0 ≤ x ≤ 3) grown on MgO (100) substrates in the form of thin films fabricated by a plasma-oxygen assisted Molecular Beam Epitaxy (MBE). X-ray absorption near-edge structure (XANES) spectra at Cr & Fe L-, and O K-edges were used to understand the electronic structure: changes in the bonding nature, valence states, and site occupancies. Cr doping in Fe3O4 results in the change of charge transfer, crystal structure, and selective occupation of ions in octahedral and tetrahedral sites. Such change modifies the electrical and magnetic properties due to the covalency of Cr ions. The physical and chemical properties of ferrites are strongly dependent on the lattice site, ion size of dopant, and magnetic nature present at different structural symmetry of the spinel structure.

  11. TiFeCoNi oxide thin film - A new composition with extremely low electrical resistivity at room temperature

    International Nuclear Information System (INIS)

    Yang, Ya-Chu; Tsau, Chun-Huei; Yeh, Jien-Wei

    2011-01-01

    We show the electrical resistivity of a TiFeCoNi oxide thin film. The electrical resistivity of the TiFeCoNi thin film decreased sharply after a suitable period of oxidation at high temperature. The lowest resistivity of the TiFeCoNi oxide film was 35 ± 3 μΩ-cm. The low electrical resistivity of the TiFeCoNi oxide thin film was attributed to Ti, which is more reactive than the other elements, reacting with oxygen at the initial stage of annealing. The low resistivity is caused by the remaining electrons.

  12. Pulsed-laser deposition and growth studies of Bi3Fe5O12 thin films

    International Nuclear Information System (INIS)

    Lux, Robert; Heinrich, Andreas; Leitenmeier, Stephan; Koerner, Timo; Herbort, Michael; Stritzker, Bernd

    2006-01-01

    Magneto-optical garnets are attractive because of their high Faraday rotation and low optical loss in the near infrared. Therefore their use is generally in nonreciprocal devices, i.e., as optical isolators in optical communication. In this paper we present data concerning the deposition of Bi 3 Fe 5 O 12 (BIG) thin films on (100) and (111) Gd 3 Ga 5 O 12 substrates using pulsed-laser deposition. Laser-induced processes on the surface of the oxide target used for ablation were analyzed and numerous films were deposited. We found the BIG film quality to be strongly affected by oxygen pressure, laser energy density, and the Bi/Fe film ratio, whereas temperature had a minor influence. We also investigated the BIG-film deposition using a target pressed from metallic Bi and Fe powders and found information on the growth behavior of BIG. We report on details of the film deposition and film properties determined by environmental scanning electron microscopy, energy dispersive x-ray analysis, Rutherford backscattering spectroscopy, and x-ray diffraction. In addition, we determined the Faraday rotation of the films

  13. Magnetic measurements of superconducting LiFeAs single crystals under high pressure

    Science.gov (United States)

    Miyoshi, Kiyotaka; Otsuka, Keisuke; Ogawa, Saki; Takeuchi, Jun

    2018-05-01

    Measurements of DC magnetization for single crystal specimens of LiFeAs have been performed under pressure using liquid argon and NaCl as pressure transmitting media (PTM) to generate hydrostatic and nearly uniaxial pressure along c-axis, respectively. It has been found that Tc linearly decreases under pressure with pressure coefficient dTc / dP ∼ - 1.6 - 1.7 K/GPa, and then shows a pressure independent behavior with Tc ∼ 8 K above 5 GPa. These behaviors are observed independently of whether we select liquid argon or NaCl as PTM. This suggests that c-axis lattice constant is not an important factor to determine Tc in LiFeAs, in contrast to KxFe2-ySe2 and (NH3)yAxFe2Se2 (A=alkali metal).

  14. Crystal structure and magnetism of layered perovskites compound EuBaCuFeO5

    Science.gov (United States)

    Lal, Surender; Mukherjee, K.; Yadav, C. S.

    2018-04-01

    Layered perovskite compounds have interesting multiferroic properties.YBaCuFeO5 is one of the layered perovskite compounds which have magnetic and dielectric transition above 200 K. The multiferroic properties can be tuned with the replacement of Y with some other rare earth ions. In this manuscript, structural and magnetic properties of layered perovskite compound EuBaCuFeO5 have been investigated. This compound crystallizes in the tetragonal structure with P4mm space group and is iso-structural with YBaCuFeO5. The magnetic transition has been found to shift to 120 K as compared to YBaCuFeO5 which has the transition at 200 K. This shift in the magnetic transition has been ascribed to the decrease in the chemical pressure that relaxes the magnetic moments.

  15. Stability of (Fe-Tm-B) amorphous alloys: relaxation and crystallization phenomena

    International Nuclear Information System (INIS)

    Zemcik, T.

    1994-01-01

    Fe-Tm-B base (TM = transition metal) amorphous alloys (metallic glasses) are thermodynamically metastable. This limits their use as otherwise favourable materials, e.g. magnetically soft, corrosion resistant and mechanically firm. By analogy of the mechanical strain-stress dependence, at a certain degree of thermal activation the amorphous structure reaches its limiting state where it changes its character and physical properties. Relaxation and early crystallization processes in amorphous alloys, starting already around 100 C, are reviewed involving subsequently stress relief, free volume shrinking, topological and chemical ordering, pre-crystallization phenomena up to partial (primary) crystallization. Two diametrically different examples are demonstrated from among the soft magnetic materials: relaxation and early crystallization processes in the Fe-Co-B metallic glasses and controlled crystallization of amorphous ribbons yielding rather modern nanocrystalline ''Finemet'' alloys where late relaxation and pre-crystallization phenomena overlap when forming extremely dispersive and fine-grained nanocrystals-in-amorphous-sauce structure. Moessbauer spectroscopy seems to be unique for magnetic and phase analysis of such complicated systems. (orig.)

  16. Characterization of β-FeSi II films as a novel solar cell semiconductor

    Science.gov (United States)

    Fukuzawa, Yasuhiro; Ootsuka, Teruhisa; Otogawa, Naotaka; Abe, Hironori; Nakayama, Yasuhiko; Makita, Yunosuke

    2006-04-01

    β-FeSi II is an attractive semiconductor owing to its extremely high optical absorption coefficient (α>10 5 cm -1), and is expected to be an ideal semiconductor as a thin film solar cell. For solar cell use, to prepare high quality β-FeSi II films holding a desired Fe/Si ratio, we chose two methods; one is a molecular beam epitaxy (MBE) method in which Fe and Si were evaporated by using normal Knudsen cells, and occasionally by e-gun for Si. Another one is the facing-target sputtering (FTS) method in which deposition of β-FeSi II films is made on Si substrate that is placed out of gas plasma cloud. In both methods to obtain β-FeSi II films with a tuned Fe/Si ratio, Fe/Si super lattice was fabricated by varying Fe and Si deposition thickness. Results showed significant in- and out-diffusion of host Fe and Si atoms at the interface of Si substrates into β-FeSi II layers. It was experimentally demonstrated that this diffusion can be suppressed by the formation of template layer between the epitaxial β-FeSi II layer and the substrate. The template layer was prepared by reactive deposition epitaxy (RDE) method. By fixing the Fe/Si ratio as precisely as possible at 1/2, systematic doping experiments of acceptor (Ga and B) and donor (As) impurities into β-FeSi II were carried out. Systematical changes of electron and hole carrier concentration in these samples along variation of incorporated impurities were observed through Hall effect measurements. Residual carrier concentrations can be ascribed to not only the remaining undesired impurities contained in source materials but also to a variety of point defects mainly produced by the uncontrolled stoichiometry. A preliminary structure of n-β-FeSi II/p-Si used as a solar cell indicated a conversion efficiency of 3.7%.

  17. Effect of irradiation temperature on crystallization of {alpha}-Fe induced by He irradiations in Fe{sub 80}B{sub 20} amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    San-noo, Toshimasa; Toriyama, Tamotsu; Wakabayashi, Hidehiko; Iijima, Hiroshi [Musashi Inst. of Tech., Tokyo (Japan); Hayashi, Nobuyuki; Sakamoto, Isao

    1997-03-01

    Since amorphous alloys are generally highly resistant to irradiation and their critical radiation dose is an order of magnitude higher for Fe-B amorphous alloy than Mo-methods, these alloys are expected to become applicable as for fusion reactor materials. The authors investigated {alpha}-Fe crystallization in an amorphous alloy, Fe{sub 80}B{sub 20} using internal conversion electron Moessbauer spectroscopy. The amount of {alpha}-Fe component was found to increase by raising the He-irradiation dose. The target part was modified to enable He ion radiation at a lower temperature (below 400 K) by cooling with Peltier element. Fe{sub 80}B{sub 20} amorphous alloy was cooled to keep the temperature at 300 K and exposed to 40 keV He ion at 1-3 x 10{sup 8} ions/cm{sup 2}. The amount of {alpha}-Fe crystal in each sample was determined. The crystal formation was not observed for He ion radiation below 2 x 10{sup 18} ions/cm{sup 2}, but that at 3 x 10{sup 8} ions/ cm{sup 2} produced a new phase ({delta} +0.40 mm/sec, {Delta} = 0.89 mm/sec). The decrease in the radiation temperature from 430 to 300 K resulted to extremely repress the production of {alpha}-Fe crystal, suggesting that the crystallization induced by He-radiation cascade is highly depending on the radiation temperature. (M.N.)

  18. Enhanced magnetic properties of chemical solution deposited BiFeO3 thin film with ZnO buffer layer

    International Nuclear Information System (INIS)

    Rajalakshmi, R.; Kambhala, Nagaiah; Angappane, S.

    2012-01-01

    Highlights: ► Enhanced magnetization of BiFeO 3 is important for strong magnetoelectric coupling. ► BiFeO 3 film with ZnO buffer layer was successfully synthesized by chemical method. ► Magnetization of BiFeO 3 has increased by more than 10 times with ZnO buffer layer. ► A mechanism for enhancement in ferromagnetism of BiFeO 3 film is proposed. - Abstract: Magnetic properties of BiFeO 3 films deposited on Si substrates with and without ZnO buffer layer have been studied in this work. We adopted the chemical solution deposition method for the deposition of BiFeO 3 as well as ZnO films. The x-ray diffraction measurements on the deposited films confirm the formation of crystalline phase of BiFeO 3 and ZnO films, while our electron microscopy measurements help to understand the morphology of few micrometers thick films. It is found that the deposited ZnO film exhibit a hexagonal particulate surface morphology, whereas BiFeO 3 film fully covers the ZnO surface. Our magnetic measurements reveal that the magnetization of BiFeO 3 has increased by more than ten times in BiFeO 3 /ZnO/Si film compared to BiFeO 3 /Si film, indicating the major role played by ZnO buffer layer in enhancing the magnetic properties of BiFeO 3 , a technologically important multiferroic material.

  19. (SiC/AlN)2 multilayer film as an effective protective coating for sintered NdFeB by magnetron sputtering

    Science.gov (United States)

    You, Yu; Li, Heqin; Huang, Yiqin; Tang, Qiong; Zhang, Jing; Xu, Jun

    2017-08-01

    SiC/AlN and (SiC/AlN)2 multilayer films with a well-arranged bilayer structure and a four-layer structure are prepared respectively on NdFeB substrates by a magnetron sputtering method. Crystal phase and microstructures of the SiC/AlN and (SiC/AlN)2 films are investigated using x-ray diffraction (XRD), field-emission scanning electron microscope (FESEM) and atomic force microscope (AFM). It is observed that the surface of the (SiC/AlN)2 four-layer film is much denser and smoother than that of the SiC/AlN bilayer film. Corrosion behaviors of the NdFeB substrates coated with SiC/AlN and (SiC/AlN)2 films as well as the bare NdFeB substrate are evaluated by potentiodynamic polarization curve tests. It is revealed that the lateral growth structures developed in interfaces are favorable for an enhanced corrosion resistance. Corrosion current densities of the (SiC/AlN)2 coated NdFeB measured in acid, alkali and salt solutions are 2.796  ×  10-9, 3.65  ×  10-6, and 2.912  ×  10-6 A cm-2, respectively, which are much lower than those of the bare NdFeB and the SiC/AlN coated NdFeB.

  20. An investigation of thin-film Ni-Fe oxide catalysts for the electrochemical evolution of oxygen.

    Science.gov (United States)

    Louie, Mary W; Bell, Alexis T

    2013-08-21

    A detailed investigation has been carried out of the structure and electrochemical activity of electrodeposited Ni-Fe films for the oxygen evolution reaction (OER) in alkaline electrolytes. Ni-Fe films with a bulk and surface composition of 40% Fe exhibit OER activities that are roughly 2 orders of magnitude higher than that of a freshly deposited Ni film and about 3 orders of magnitude higher than that of an Fe film. The freshly deposited Ni film increases in activity by as much as 20-fold during exposure to the electrolyte (KOH); however, all films containing Fe are stable as deposited. The oxidation of Ni(OH)2 to NiOOH in Ni films occurs at potentials below the onset of the OER. Incorporation of Fe into the film increases the potential at which Ni(OH)2/NiOOH redox occurs and decreases the average oxidation state of Ni in NiOOH. The Tafel slope (40 mV dec(-1)) and reaction order in OH(-) (1) for the mixed Ni-Fe films (containing up to 95% Fe) are the same as those for aged Ni films. In situ Raman spectra acquired in 0.1 M KOH at OER potentials show two bands characteristic of NiOOH. The relative intensities of these bands vary with Fe content, indicating a change in the local environment of Ni-O. Similar changes in the relative intensities of the bands and an increase in OER activity are observed when pure Ni films are aged. These observations suggest that the OER is catalyzed by Ni in Ni-Fe films and that the presence of Fe alters the redox properties of Ni, causing a positive shift in the potential at which Ni(OH)2/NiOOH redox occurs, a decrease in the average oxidation state of the Ni sites, and a concurrent increase in the activity of Ni cations for the OER.

  1. On crystallization of bisphenol-A polycarbonate thin films upon annealing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chunhong; Li, Qichao; Mao, Wenfeng; Wang, Peng; He, Chunqing, E-mail: hecq@whu.edu.cn

    2015-10-16

    Crystallization of polycarbonate (PC) films as a function of annealing time has been investigated by various methods. A distinct diffraction peak at 17.56°, a sharp decrease of film thickness, an increase of refractive index and branch-type structures on the surface are found merely for the film after crystallization. Interestingly, positron annihilation parameters demonstrate fractional free-volumes in PC films vary significantly not only before crystallization but also at the early stage of annealing, which are not found by other methods. The results show that free-volumes in PC film must be increased remarkably before crystallization, which enables the occurrence of molecule rearrangement. - Highlights: • Fractional free-volume in PC film decreased of early stage of annealing. • Crystallization of PC film on Si substrate occurred after annealed for ∼48 hours. • Fractional free-volume in PC film increased remarkably before crystallization. • Positron diffusion length and S parameter revealed the variation of free volumes.

  2. On crystallization of bisphenol-A polycarbonate thin films upon annealing

    International Nuclear Information System (INIS)

    Yang, Chunhong; Li, Qichao; Mao, Wenfeng; Wang, Peng; He, Chunqing

    2015-01-01

    Crystallization of polycarbonate (PC) films as a function of annealing time has been investigated by various methods. A distinct diffraction peak at 17.56°, a sharp decrease of film thickness, an increase of refractive index and branch-type structures on the surface are found merely for the film after crystallization. Interestingly, positron annihilation parameters demonstrate fractional free-volumes in PC films vary significantly not only before crystallization but also at the early stage of annealing, which are not found by other methods. The results show that free-volumes in PC film must be increased remarkably before crystallization, which enables the occurrence of molecule rearrangement. - Highlights: • Fractional free-volume in PC film decreased of early stage of annealing. • Crystallization of PC film on Si substrate occurred after annealed for ∼48 hours. • Fractional free-volume in PC film increased remarkably before crystallization. • Positron diffusion length and S parameter revealed the variation of free volumes

  3. Capping layer-tailored interface magnetic anisotropy in ultrathin Co{sub 2}FeAl films

    Energy Technology Data Exchange (ETDEWEB)

    Belmeguenai, M., E-mail: belmeguenai.mohamed@univ-paris13.fr; Zighem, F.; Chérif, S. M. [LSPM (CNRS-UPR 3407), Université Paris 13, Sorbonne Paris Cité, 99 Avenue Jean-Baptiste Clément, 93430 Villetaneuse (France); Gabor, M. S., E-mail: mihai.gabor@phys.utcluj.ro; Petrisor, T. [Center for Superconductivity, Spintronics and Surface Science, Department of Physics and Chemistry, Technical University of Cluj-Napoca, Str. Memorandumului No. 28, RO-400114 Cluj-Napoca (Romania); Tiusan, C. [Center for Superconductivity, Spintronics and Surface Science, Department of Physics and Chemistry, Technical University of Cluj-Napoca, Str. Memorandumului No. 28, RO-400114 Cluj-Napoca (Romania); Institut Jean Lamour, CNRS, Lorraine Université, BP 70239, F-54506 Vandoeuvre (France)

    2015-01-14

    Co{sub 2}FeAl (CFA) thin films of various thicknesses (2 nm ≤ d ≤ 50 nm) have been grown on (001) MgO single crystal substrates and then capped with Cr, V, and Ta. Their magnetic and structural properties have been studied by x-ray diffraction (XRD), vibrating sample magnetometry, and broadband microstrip ferromagnetic resonance (MS-FMR). The XRD revealed that the films are epitaxial with the cubic [001] CFA axis normal to the substrate plane and that the chemical order varies from the B2 phase to the A2 phase when decreasing the thickness. The deduced lattice parameters showed that the Cr-capped films exhibit a larger tetragonal distortion, as compared with the films capped with V or Ta. The presence of magnetic dead layers has been observed in CFA samples capped with V and Ta but not in the case of the Cr-capped ones. The effective magnetization, deduced from the fit of MS-FMR measurements, increases (decreases) linearly with the CFA inverse thickness (1/d) for the Cr-capped (Ta-capped) films while it is constant for the V-capped ones. This allows quantifying the perpendicular surface anisotropy coefficients of −0.46 erg/cm{sup 2} and 0.74 erg/cm{sup 2} for Cr and Ta-capped films, respectively. Moreover, the fourfold and the uniaxial anisotropy fields, measured in these films, showed different trends with a respect to the CFA inverse thickness. This allows inferring that a non-negligible part of the fourfold magnetocrystalline term is of interfacial origin.

  4. Growth of Ferromagnetic Epitaxial Film of Hexagonal FeGe on (111) Ge Surface

    Science.gov (United States)

    Kumar, Dushyant; Joshi, P. C.; Hossain, Z.; Budhani, R. C.

    2014-03-01

    The realization of semiconductors showing ferromagnetic order at easily accessible temperatures has been of interest due to their potential use in spintronic devices where long spin life times are of key interest. We have realized the growth of FeGe thin films on Ge (111) wafers using pulsed laser deposition (PLD). The stoichiometric and single phase FeGe target used in PLD chamber has been made by arc melting. A typical θ-2 θ diffraction spectra performed on 40 nm thick FeGe film suggests the stabilization of β-Ni2In (B82-type) hexagonal phase with an epitaxial orientation of (0001)FeGe ||(111)Ge and [11-20]FeGe ||[-110]Ge. SEM images shows a granular structure with the formation of very large grains of about 100 to 500 nm in lateral dimension. The magnetization vs. temperature data taken from SQUID reveal the TC of ~ 270K. Since, PLD technique makes it easier to stabilize the B82 (Ni2In) hexagonal phase in thin FeGe films, this work opens opportunities to reinvestigate many conflicting results on various properties of the FeGe system.

  5. Anisotropic magnetoresistance across Verwey transition in charge ordered Fe3O4 epitaxial films

    KAUST Repository

    Liu, Xiang

    2017-12-26

    The anisotropic magnetoresistance (AMR) near the Verwey temperature (T-V) is investigated in charge ordered Fe3O4 epitaxial films. When the temperature continuously decreases below T-V, the symmetry of AMR in Fe3O4(100) film evolves from twofold to fourfold at a magnetic field of 50 kOe, where the magnetic field is parallel to the film surface, whereas AMR in Fe3O4(111) film maintains twofold symmetry. By analyzing AMR below T-V, it is found that the Verwey transition contains two steps, including a fast charge ordering process and a continuous formation process of trimeron, which is comfirmed by the temperature-dependent Raman spectra. Just below T-V, the twofold AMR in Fe3O4(100) film originates from uniaxial magnetic anisotropy. The fourfold AMR at a lower temperature can be ascribed to the in-plane trimerons. By comparing the AMR in the films with two orientations, it is found that the trimeron shows a smaller resistivity in a parallel magnetic field. The field-dependent AMR results show that the trimeron-sensitive field has a minimum threshold of about 2 kOe.

  6. Synthesis and characterization of Fe3+ doped TiO2 nanoparticles and films and their performance for photocurrent response under UV illumination

    International Nuclear Information System (INIS)

    Elghniji, Kais; Atyaoui, Atef; Livraghi, Stefano; Bousselmi, Latifa; Giamello, Elio; Ksibi, Mohamed

    2012-01-01

    Graphical abstract: Schematic diagram illustrating the charge transfer from excited TiO 2 to the different states of Fe 3+ ions; C B and V B refer to the energy levels of the conduction and valence bands of TiO 2 , respectively. Highlights: ► In this study we examine the Iron as catalyst precursor to synthesize the Fe 3+ doped TiO 2 nanoparticles. ► The Fe 3+ doped TiO 2 catalysts show the presence of a mixed phase of anatase. ► The iron is completely absent in the XRD pattern of the doped iron TiO 2 powder. ► The analysis of EPR result further confirms that Fe 3+ ion are successfully doped in the TiO 2 lattice by substituting Ti 4+ . ► Fe 3+ doping can efficiently separate the photo-generated electrons and holes. - Abstract: Undoped TiO 2 and Fe 3+ doped (0.1, 0.3, 0.6 and 1 wt.%) TiO 2 nanoparticles have been synthesized by the acid-catalyzed sol–gel method. Iron cations are introduced in the initial solution, before gelification, what promotes their lattice localization. The Fe 3+ doped TiO 2 films have been fabricated using a dip-coating technique. The effect of iron content on the crystalline structure, phase transformation and grain growth were determined by X-ray diffraction (XRD), Raman spectroscopy, UV–visible diffused reflectance spectroscopy (DRS) and Electron paramagnetic resonance (EPR) spectroscopy. It has demonstrated that all catalysts are composed of mixed-phase crystals of anatase and brookite with anatase as dominant phase. The crystallinity of the brookite and anatase phases decreased with increasing the iron content. The analysis of EPR result further confirms that Fe 3+ ion are successfully doped in the TiO 2 lattice by substituting Ti 4+ . It was demonstrated that Fe 3+ ion in the TiO 2 films plays a role as the intermediate for the efficient separation of photogenerated hole–electron pairs and increases the photocurrent response of the film under UV light irradiation. The maximum photocurrent is obtained on the Fe 3+ doped Ti

  7. Synthesis and characterization of Fe{sup 3+} doped TiO{sub 2} nanoparticles and films and their performance for photocurrent response under UV illumination

    Energy Technology Data Exchange (ETDEWEB)

    Elghniji, Kais [University of Sfax, Laboratoire Eau, Energie et Environnement (LR3E), Ecole Nationale d' Ingenieurs de Sfax, B.P. 1173, 3038 Sfax (Tunisia); Atyaoui, Atef [Centre de Recherches et des Technologies des Eaux, Technopole de Borj Cedria B.P. 273, 8020 Soliman (Tunisia); Livraghi, Stefano [Dipartimento di Chimica I.F.M and NIS, Universita degli Studi di Torino, Via P. Giuria, 7 10125 Torino (Italy); Bousselmi, Latifa [Centre de Recherches et des Technologies des Eaux, Technopole de Borj Cedria B.P. 273, 8020 Soliman (Tunisia); Giamello, Elio [Dipartimento di Chimica I.F.M and NIS, Universita degli Studi di Torino, Via P. Giuria, 7 10125 Torino (Italy); Ksibi, Mohamed, E-mail: Mohamed.Ksibi@tunet.tn [University of Sfax, Laboratoire Eau, Energie et Environnement (LR3E), Ecole Nationale d' Ingenieurs de Sfax, B.P. 1173, 3038 Sfax (Tunisia)

    2012-11-15

    Graphical abstract: Schematic diagram illustrating the charge transfer from excited TiO{sub 2} to the different states of Fe{sup 3+} ions; C{sub B} and V{sub B} refer to the energy levels of the conduction and valence bands of TiO{sub 2}, respectively. Highlights: Black-Right-Pointing-Pointer In this study we examine the Iron as catalyst precursor to synthesize the Fe{sup 3+} doped TiO{sub 2} nanoparticles. Black-Right-Pointing-Pointer The Fe{sup 3+} doped TiO{sub 2} catalysts show the presence of a mixed phase of anatase. Black-Right-Pointing-Pointer The iron is completely absent in the XRD pattern of the doped iron TiO{sub 2} powder. Black-Right-Pointing-Pointer The analysis of EPR result further confirms that Fe{sup 3+} ion are successfully doped in the TiO{sub 2} lattice by substituting Ti{sup 4+}. Black-Right-Pointing-Pointer Fe{sup 3+} doping can efficiently separate the photo-generated electrons and holes. - Abstract: Undoped TiO{sub 2} and Fe{sup 3+} doped (0.1, 0.3, 0.6 and 1 wt.%) TiO{sub 2} nanoparticles have been synthesized by the acid-catalyzed sol-gel method. Iron cations are introduced in the initial solution, before gelification, what promotes their lattice localization. The Fe{sup 3+} doped TiO{sub 2} films have been fabricated using a dip-coating technique. The effect of iron content on the crystalline structure, phase transformation and grain growth were determined by X-ray diffraction (XRD), Raman spectroscopy, UV-visible diffused reflectance spectroscopy (DRS) and Electron paramagnetic resonance (EPR) spectroscopy. It has demonstrated that all catalysts are composed of mixed-phase crystals of anatase and brookite with anatase as dominant phase. The crystallinity of the brookite and anatase phases decreased with increasing the iron content. The analysis of EPR result further confirms that Fe{sup 3+} ion are successfully doped in the TiO{sub 2} lattice by substituting Ti{sup 4+}. It was demonstrated that Fe{sup 3+} ion in the TiO{sub 2} films

  8. Ultralong Lifespan and Ultrafast Li Storage: Single-Crystal LiFePO4 Nanomeshes.

    Science.gov (United States)

    Zhang, Yan; Zhang, Hui Juan; Feng, Yang Yang; Fang, Ling; Wang, Yu

    2016-01-27

    A novel LiFePO4 material, in the shape of a nanomesh, has been rationally designed and synthesized based on the low crystal-mismatch strategy. The LiFePO4 nanomesh possesses several advantages in morphology and crystal structure, including a mesoporous structure, its crystal orientation that is along the [010] direction, and a shortened Li-ion diffusion path. These properties are favorable for their application as cathode in Li-ion batteries, as these will accelerate the Li-ion diffusion rate, improve the Li-ion exchange between the LiFePO4 nanomesh and the electrolyte, and reduce the Li-ion capacitive behavior during Li intercalation. So the LiFePO4 nanomesh exhibits a high specific capacity, enhanced rate capability, and strengthened cyclability. The method developed here can also be extended to other similar systems, for instance, LiMnPO4 , LiCoPO4 , and LiNiPO4 , and may find more applications in the designed synthesis of functional materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. 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.

  10. Magnetoelectric coupling effect in transition metal modified polycrystalline BiFeO3 thin films

    International Nuclear Information System (INIS)

    Sreenivas Puli, Venkata; Kumar Pradhan, Dhiren; Gollapudi, Sreenivasulu; Coondoo, Indrani; Panwar, Neeraj; Adireddy, Shiva; Chrisey, Douglas B.; Katiyar, Ram S.

    2014-01-01

    Rare-earth (Sm) and transition metal (Co) modified polycrystalline BiFeO 3 (BFO) thin films have been deposited on Pt/TiO 2 /SiO 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 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 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 3 thin films prepared using PLD. • High ME-coupling response was observed in co-substituted BiFeO 3 thin films. • High magnetization ∼35 emu/cm 3 at a maximum field of H ∼20 kOe. • Low leakage current might be due to co-substitution in BiFeO 3 thin films. • A notable piezoelectric constant d 33 ∼94 pm/V was found in BiFeO 3 thin films

  11. Fabrication and properties of SmFe2-PZT magnetoelectric thin films

    KAUST Repository

    Giouroudi, Ioanna

    2013-05-17

    Magnetoelectric (ME) thin film composites are attracting a continually increasing interest due to their unique features and potential applications in multifunctional microdevices and integrated units such as sensors, actuators and energy harvesting modules. By combining piezoelectric and highly magnetostrictive thin films, the potentialities of these materials increase. In this paper we report the fabrication of SmFe2 and PZT thin films and the investigation of their properties. First of all, a ~ 400 nm thin SmFe film was deposited on top of Si/SiO2 substrate by magnetron sputter deposition. Afterwards, a 140 nm Pt bottom electrode was sputtered on top of the SmFe film forming a bottom electrode. Spin coating was employed for the deposition of the 150 nm thin PZT layer. A PZT solution with 10 %Pb excess was utilized for this fabrication step. Finally, circular Pt top electrodes were sputtered as top electrodes. This paper focuses on the microstructure of the individual films characterized by X-Ray diffractometer (XRD) and scanning electron microscopy (SEM). A piezoelectric evaluation system, aixPES, with TF2000E analyzer component was used for the electric hysteresis measurements of PZT thin films and a vibrating sample magnetometer (VSM) was employed for the magnetic characterization of the SmFe. The developed thin films and the fabricated double layer SmFe-PZT exhibit both good ferromagnetic and piezoelectric responses which predict a promising ME composite structure. The quantitative chemical composition of the samples was confirmed by energy dispersive spectroscopy (EDX). © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  12. Fabrication and properties of SmFe2-PZT magnetoelectric thin films

    KAUST Repository

    Giouroudi, Ioanna; Alnassar, Mohammed; Kosel, Jü rgen

    2013-01-01

    Magnetoelectric (ME) thin film composites are attracting a continually increasing interest due to their unique features and potential applications in multifunctional microdevices and integrated units such as sensors, actuators and energy harvesting modules. By combining piezoelectric and highly magnetostrictive thin films, the potentialities of these materials increase. In this paper we report the fabrication of SmFe2 and PZT thin films and the investigation of their properties. First of all, a ~ 400 nm thin SmFe film was deposited on top of Si/SiO2 substrate by magnetron sputter deposition. Afterwards, a 140 nm Pt bottom electrode was sputtered on top of the SmFe film forming a bottom electrode. Spin coating was employed for the deposition of the 150 nm thin PZT layer. A PZT solution with 10 %Pb excess was utilized for this fabrication step. Finally, circular Pt top electrodes were sputtered as top electrodes. This paper focuses on the microstructure of the individual films characterized by X-Ray diffractometer (XRD) and scanning electron microscopy (SEM). A piezoelectric evaluation system, aixPES, with TF2000E analyzer component was used for the electric hysteresis measurements of PZT thin films and a vibrating sample magnetometer (VSM) was employed for the magnetic characterization of the SmFe. The developed thin films and the fabricated double layer SmFe-PZT exhibit both good ferromagnetic and piezoelectric responses which predict a promising ME composite structure. The quantitative chemical composition of the samples was confirmed by energy dispersive spectroscopy (EDX). © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  13. Nano size crystals of goethite, α-FeOOH: Synthesis and thermal transformation

    Science.gov (United States)

    Christensen, Axel Nørlund; Jensen, Torben R.; Bahl, Christian R. H.; DiMasi, Elaine

    2007-04-01

    An aqueous suspension of amorphous iron(III) hydroxide was kept at room temperature (298 K) for 23 years. During this period of time the pH of the liquid phase changed from 4.3 to 2.85, and nano size crystals of goethite, α-FeOOH crystallised from the amorphous iron(III) hydroxide. Transmission electron microscopy (TEM) investigations, Mössbauer spectra, and powder X-ray diffraction using Co K α radiation showed that the only iron containing crystalline phase present in the recovered product was α-FeOOH. The size of these nano particles range from 10 to 100 nm measured by TEM. The thermal decomposition of α-FeOOH was investigated by time-resolved in situ synchrotron radiation powder X-ray diffraction and the data showed that the sample of α-FeOOH transformed to α-Fe 2O 3 in the temperature range 444-584 K. A quantitative phase analysis shows the increase in scattered X-ray intensity from α-Fe 2O 3 to follow the decrease of intensity from α-FeOOH in agreement with the topotactic phase transition.

  14. Crystal growth and characterization of CeFe{sub 1-x}Ru{sub x} PO

    Energy Technology Data Exchange (ETDEWEB)

    Balle, Tanita; Kliemt, Kristin; Krellner, Cornelius [Goethe Universitaet Frankfurt, Kristall- und Materiallabor (Germany)

    2016-07-01

    CeRuPO is a one of the few heavy fermion systems, which order ferromagnetically at low temperatures (T{sub C} = 15 K), because of dominant RKKY-interaction. CeFePO on the other hand shows no long-range magnetic order even at low temperatures because of dominant Kondo effect (T{sub K} = 10 K). By substituting CeFePO with ruthenium we can reach a quantum critical point, at which the RKKY-interaction and the Kondo effect are equally strong. To study the quantum critical point, and to enlighten the question if the order stays ferromagnetically down to lowest temperatures, high quality crystals are needed. Here, the growth and characterization of the single crystals will be discussed. We obtained mm-sized single crystals of the unsubstituted CeRuPO and CeFePO by a modified Bridgeman method using tin as a flux. The quality of the crystals was verified by Powder-X-Ray-Diffraction, energy dispersive X-ray spectroscopy and Laue backscattering.

  15. Optical and magneto-optical characterization of TbFeCo and GdFeCo thin films for high-density recording

    International Nuclear Information System (INIS)

    Hendren, W R; Atkinson, R; Pollard, R J; Salter, I W; Wright, C D; Clegg, W W; Jenkins, D F L

    2003-01-01

    Thin, optically semi-infinite films of amorphous TbFeCo and GdFeCo, suitable for magneto-optical recording, have been deposited by DC magnetron sputtering onto glass. Ellipsometric techniques have been used to determine the complex refractive index and complex magneto-optical parameter of the films in the wavelength range 400-900 nm, thus characterizing the materials. A review of the literature is presented and shows that the results for the TbFeCo films compare favourably with published results obtained from measurements conducted in situ, with the films protected with ZnS barrier layers. It is found that GdFeCo and TbFeCo are optically very similar, but magneto-optically the materials are quite different

  16. Optical and magneto-optical characterization of TbFeCo and GdFeCo thin films for high-density recording

    Energy Technology Data Exchange (ETDEWEB)

    Hendren, W R [Department of Pure and Applied Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Atkinson, R [Department of Pure and Applied Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Pollard, R J [Department of Pure and Applied Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Salter, I W [Department of Pure and Applied Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Wright, C D [School of Engineering and Computer Science, University of Exeter, Exeter EX4 4QF (United Kingdom); Clegg, W W [CRIST, University of Plymouth, Plymouth PL4 8AA (United Kingdom); Jenkins, D F L [CRIST, University of Plymouth, Plymouth PL4 8AA (United Kingdom)

    2003-03-12

    Thin, optically semi-infinite films of amorphous TbFeCo and GdFeCo, suitable for magneto-optical recording, have been deposited by DC magnetron sputtering onto glass. Ellipsometric techniques have been used to determine the complex refractive index and complex magneto-optical parameter of the films in the wavelength range 400-900 nm, thus characterizing the materials. A review of the literature is presented and shows that the results for the TbFeCo films compare favourably with published results obtained from measurements conducted in situ, with the films protected with ZnS barrier layers. It is found that GdFeCo and TbFeCo are optically very similar, but magneto-optically the materials are quite different.

  17. Flash-lamp-crystallized polycrystalline silicon films with high hydrogen concentration formed from Cat-CVD a-Si films

    International Nuclear Information System (INIS)

    Ohdaira, Keisuke; Tomura, Naohito; Ishii, Shohei; Matsumura, Hideki

    2011-01-01

    We investigate residual forms of hydrogen (H) atoms such as bonding configuration in poly-crystalline silicon (poly-Si) films formed by the flash-lamp-induced crystallization of catalytic chemical vapor deposited (Cat-CVD) a-Si films. Raman spectroscopy reveals that at least part of H atoms in flash-lamp-crystallized (FLC) poly-Si films form Si-H 2 bonds as well as Si-H bonds with Si atoms even using Si-H-rich Cat-CVD a-Si films, which indicates the rearrangement of H atoms during crystallization. The peak desorption temperature during thermal desorption spectroscopy (TDS) is as high as 900 o C, similar to the reported value for bulk poly-Si.

  18. Corrosion resistance of sintered NdFeB coated with SiC/Al bilayer thin films by magnetron sputtering

    Science.gov (United States)

    Huang, Yiqin; Li, Heqin; Zuo, Min; Tao, Lei; Wang, Wei; Zhang, Jing; Tang, Qiong; Bai, Peiwen

    2016-07-01

    The poor corrosion resistance of sintered NdFeB imposes a great challenge in industrial applications. In this work, the SiC/Al bilayer thin films with the thickness of 510 nm were deposited on sintered NdFeB by magnetron sputtering to improve the corrosion resistance. A 100 nm Al buffer film was used to reduce the internal stress between SiC and NdFeB and improve the surface roughness of the SiC thin film. The morphologies and structures of SiC/Al bilayer thin films and SiC monolayer film were investigated with FESEM, AFM and X-ray diffraction. The corrosion behaviors of sintered NdFeB coated with SiC monolayer film and SiC/Al bilayer thin films were analyzed by polarization curves. The magnetic properties were measured with an ultra-high coercivity permanent magnet pulse tester. The results show that the surface of SiC/Al bilayer thin films is more compact and uniform than that of SiC monolayer film. The corrosion current densities of SiC/Al bilayer films coated on NdFeB in acid, alkali and salt solutions are much lower than that of SiC monolayer film. The SiC/Al bilayer thin films have little influence to the magnetic properties of NdFeB.

  19. Thermal evolution of the crystal structure of the orthorhombic perovskite LaFeO3

    International Nuclear Information System (INIS)

    Dixon, Charlotte A.L.; Kavanagh, Christopher M.; Knight, Kevin S.; Kockelmann, Winfried; Morrison, Finlay D.; Lightfoot, Philip

    2015-01-01

    The thermal evolution of the crystal structure of the prototypical orthorhombic perovskite LaFeO 3 has been studied in detail by powder neutron diffraction in the temperature range 25FeO 3 . However, an unexpected behavior is seen in the nature of the intra-octahedral distortion, which is used to rationalize the unique occurrence of a temperature dependent crossover of the a and c unit cell metrics in this compound. - Graphical abstract: The unusual thermal evolution of lattice metrics in the perovskite LaFeO 3 is rationalized from a detailed powder neutron diffraction study. - Highlights: • Crystal structure of the perovskite LaFeO 3 studied in detail by powder neutron diffraction. • Unusual thermal evolution of lattice metrics rationalized. • Contrasting behavior to Bi-doped LaFeO 3 . • Octahedral distortion/tilt parameters explain unusual a and c lattice parameter behavior

  20. Epitaxial growth of Co(0 0 0 1)hcp/Fe(1 1 0)bcc magnetic bi-layer films on SrTiO3(1 1 1) substrates

    International Nuclear Information System (INIS)

    Ohtake, Mitsuru; Shikada, Kouhei; Kirino, Fumiyoshi; Futamoto, Masaaki

    2008-01-01

    Co(0 0 0 1) hcp /Fe(1 1 0) bcc epitaxial magnetic bi-layer films were successfully prepared on SrTiO 3 (1 1 1) substrates. The crystallographic properties of Co/Fe epitaxial magnetic bi-layer films were investigated. Fe(1 1 0) bcc soft magnetic layer grew epitaxially on SrTiO 3 (1 1 1) substrate with two type variants, Nishiyama-Wasserman and Kurdjumov-Sachs relationships. An hcp-Co single-crystal layer is obtained on Ru(0 0 0 1) hcp interlayer, while hcp-Co layer formed on Au(1 1 1) fcc or Ag(1 1 1) fcc interlayer is strained and may involve fcc-Co phase. It has been shown possible to prepare Co/Fe epitaxial magnetic bi-layer films which can be usable for patterned media application

  1. Crystallization history of enriched shergottites from Fe and Mg isotope fractionation in olivine megacrysts

    Science.gov (United States)

    Collinet, Max; Charlier, Bernard; Namur, Olivier; Oeser, Martin; Médard, Etienne; Weyer, Stefan

    2017-06-01

    Martian meteorites are the only samples available from the surface of Mars. Among them, olivine-phyric shergottites are basalts containing large zoned olivine crystals with highly magnesian cores (Fo 70-85) and rims richer in Fe (Fo 45-60). The Northwest Africa 1068 meteorite is one of the most primitive "enriched" shergottites (high initial 87Sr/86Sr and low initial ε143Nd). It contains olivine crystals as magnesian as Fo 77 and is a major source of information to constrain the composition of the parental melt, the composition and depth of the mantle source, and the cooling and crystallization history of one of the younger magmatic events on Mars (∼180 Ma). In this study, Fe-Mg isotope profiles analyzed in situ by femtosecond-laser ablation MC-ICP-MS are combined with compositional profiles of major and trace elements in olivine megacrysts. The cores of olivine megacrysts are enriched in light Fe isotopes (δ56FeIRMM-14 = -0.6 to -0.9‰) and heavy Mg isotopes (δ26MgDSM-3 = 0-0.2‰) relative to megacryst rims and to the bulk martian isotopic composition (δ56Fe = 0 ± 0.05‰, δ26Mg = -0.27 ± 0.04‰). The flat forsterite profiles of megacryst cores associated with anti-correlated fractionation of Fe-Mg isotopes indicate that these elements have been rehomogenized by diffusion at high temperature. We present a 1-D model of simultaneous diffusion and crystal growth that reproduces the observed element and isotope profiles. The simulation results suggest that the cooling rate during megacryst core crystallization was slow (43 ± 21 °C/year), and consistent with pooling in a deep crustal magma chamber. The megacryst rims then crystallized 1-2 orders of magnitude faster during magma transport toward the shallower site of final emplacement. Megacryst cores had a forsterite content 3.2 ± 1.5 mol% higher than their current composition and some were in equilibrium with the whole-rock composition of NWA 1068 (Fo 80 ± 1.5). NWA 1068 composition is thus close to a

  2. Structure and magnetic properties of Co2FeSi film deposited on Si/SiO2 substrate with Cr buffer layer

    Science.gov (United States)

    Chatterjee, Payel; Basumatary, Himalay; Raja, M. Manivel

    2018-05-01

    Co2FeSi thin films of 25 nm thickness with 50 nm thick Cr buffer layer was deposited on thermally oxidized Si substrates. Structural and magnetic properties of the films were studied as a function of annealing temperature and substrate temperatures. While the coercivity increases with increase in annealing temperature, it is found to decrease with increase in substrate temperature. A minimum coercivity of 18 Oe has been obtained for the film deposited at 550°C substrate temperature. This was attributed to the formation of L12 phase as observed from the GIXRD studies. The films with a good combination of soft magnetic properties and L21 crystal structure are suitable for spintronic applications.

  3. Soft magnetism, magnetostriction, and microwave properties of FeGaB thin films

    International Nuclear Information System (INIS)

    Lou, J.; Insignares, R. E.; Cai, Z.; Ziemer, K. S.; Liu, M.; Sun, N. X.

    2007-01-01

    A series of (Fe 100-y Ga y ) 1-x B x (x=0-21 and y=9-17) films were deposited; their microstructure, soft magnetism, magnetostrictive behavior, and microwave properties were investigated. The addition of B changes the FeGaB films from polycrystalline to amorphous phase and leads to excellent magnetic softness with coercivity s , self-biased ferromagnetic resonance (FMR) frequency of 1.85 GHz, narrow FMR linewidth (X band) of 16-20 Oe, and a high saturation magnetostriction constant of 70 ppm. The combination of these properties makes the FeGaB films potential candidates for tunable magnetoelectric microwave devices and other rf/microwave magnetic device applications

  4. Scaling of Anomalous Hall Effects in Facing-Target Reactively Sputtered Fe4N Films

    KAUST Repository

    Zhang, Yan

    2015-05-13

    Anomalous Hall effect (AHE) in the reactively sputtered epitaxial and polycrystalline γ′-Fe4N films is investigated systematically. The Hall resistivity is positive in the entire temperature range. The magnetization, carrier density and grain boundaries scattering have a major impact on the AHE scaling law. The scaling exponent γ in the conventional scaling of is larger than 2 in both the epitaxial and polycrystalline γ′-Fe4N films. Although γ>2 has been found in heterogeneous systems due to the effects of the surface and interface scattering on AHE, γ>2 is not expected in homogenous epitaxial systems. We demonstrated that γ>2 results from residual resistivity (ρxx0) in γ′-Fe4N films. Furthermore, the side-jump and intrinsic mechanisms are dominant in both epitaxial and polycrystalline samples according to the proper scaling relation.

  5. Magnetization reversal mechanism of Nd-Fe-B films with perpendicular magnetic anisotropy

    International Nuclear Information System (INIS)

    Liu Xiaoxi; Ishida, Go; Morisako, Akimitsu

    2011-01-01

    The microstructure and magnetic properties of Nd-Fe-B films with thicknesses from 100 nm to 3 nm have been investigated. All the films show excellent perpendicular magnetic anisotropy with a squareness ratio of 1 in the perpendicular direction and almost zero coercivity in the in-plane direction. Of particular interest is that the initial magnetization curves sensitively depended on the film thickness. Films thicker than 15 nm show steep initial magnetization curve. Although the films have coercivities larger than 21 kOe, the films can be fully magnetized from the thermally demagnetized state with a field as small as 5 kOe. With the decrease of film thickness to 5 nm, the initial magnetization curve becomes flat. The evolution of initial magnetization curves with film thickness can be understood by the microstructure of the films. Films with thickness of 15 nm show close-packed grains without any intergranular phases. Such microstructures lead to steep initial magnetization curves. On the other hand, when the film thickness decreased to 3 nm, the film thickness became nonuniform. Such microstructure leads to flat initial magnetization curves.

  6. Dipole pinning effect on photovoltaic characteristics of ferroelectric BiFeO3 films

    Science.gov (United States)

    Biswas, P. P.; Thirmal, Ch.; Pal, S.; Murugavel, P.

    2018-01-01

    Ferroelectric bismuth ferrite is an attractive candidate for switchable devices. The effect of dipole pinning due to the oxygen vacancy layer on the switching behavior of the BiFeO3 thin film fabricated by the chemical solution deposition method was studied after annealing under air, O2, and N2 environment. The air annealed film showed well defined and dense grains leading to a lower leakage current and superior electrical properties compared to the other two films. The photovoltage and transient photocurrent measured under positive and negative poling elucidated the switching nature of the films. Though the air and O2 annealed films showed a switchable photovoltaic response, the response was severely affected by oxygen vacancies in the N2 annealed film. In addition, the open circuit voltage was found to be mostly dependent on the polarization of BiFeO3 rather than the Schottky barriers at the interface. This work provides an important insight into the effect of dipole pinning caused by oxygen vacancies on the switchable photovoltaic effect of BiFeO3 thin films along with the importance of stoichiometric, defect free, and phase pure samples to facilitate meaningful practical applications.

  7. Crystal structure of a Ce2Fe2Mg15 compound

    International Nuclear Information System (INIS)

    Opainich, I.M.; Pavlyuk, V.V.; Bodak, O.I.

    1996-01-01

    A structure of a new Ce2Fe2Mg15 ternary compound (P63/mmc sp.gr., a=1.0324(5) nm, c=1.02080(4) nm) was determined by powder methods on a DRON-4.07 automatic diffractometer. The structure of a Ce2Fe2Mg15 crystal is a new variant of the ordered Th2Ni17 type superstructure, in which cerium atoms occupy the thorium positions; magnesium atoms occupy the nickel position 6g, 12k, and 12j; and iron atoms occupy the 4f position

  8. Crystal growth and properties of PbI2 doped with Fe and Ni

    International Nuclear Information System (INIS)

    Rybak, O.V.; Lun', Yu.O.; Bordun, I.M.; Omelyan, M.F.

    2005-01-01

    A procedure is described for doping PbI 2 monocrystals with Fe and Ni during vapor-phase growth in a closed system in the presence of excess iodine. The rate of mass transfer in the system and the doping level of the crystals are shown to be governed by the dopant content in the source material and the source temperature. The effect of Fe and Ni doping on the low-temperature (5 K) exciton photoluminescence spectrum of PbI 2 is discussed [ru

  9. Spin-waves in antiferromagnetic single crystal LiFePO$_4$

    OpenAIRE

    Li, Jiying; Garlea, Vasile O.; Zarestky, Jerel L.; Vaknin, David

    2005-01-01

    Spin-wave dispersions in the antiferromagnetic state of single crystal LiFePO$_4$ were determined by inelastic neutron scattering measurements. The dispersion curves measured from the (010) reflection along both {\\it a}$^\\ast$ and {\\it b}$^\\ast$ reciprocal-space directions reflect the anisotropic coupling of the layered Fe$^{2+}$ (S = 2) spin-system. The spin-wave dispersion curves were theoretically modeled using linear spin-wave theory by including in the spin-Hamiltonian in-plane nearest- ...

  10. Direct Observation of High-Temperature Superconductivity in One-Unit-Cell FeSe Films

    International Nuclear Information System (INIS)

    Zhang Wen-Hao; Zhang Jin-Song; Li Fang-Sen; Guo Ming-Hua; Ding Hao; Tang Chen-Jia; Wang Qing-Yan; He Ke; Ji Shuai-Hua; Chen Xi; Sun Yi; Zhao Yan-Fei; Xing Ying; Wang Hui-Chao; Zhang Hui-Min; Peng Jun-Ping; Li Zhi; Wang Meng; Fujita Takeshi; Hirata Akihiko

    2014-01-01

    We prepared one-unit-cell (1-UC) thick FeSe films on insulating SrTiO 3 substrates with non-superconducting FeTe protection layers by molecular beam epitaxy for ex situ studies. By direct transport and magnetic measurements, we provide definitive evidence for high temperature superconductivity in the 1-UC FeSe films with an onset T C above 40 K and an extremely large critical current density J C ∼1.7×10 6 A/cm 2 at 2 K, which are much higher than T C ∼8 K and J C ∼10 4 A/cm 2 for bulk FeSe, respectively. Our work may pave the way to enhancing and tailoring superconductivity by interface engineering. (express letter)

  11. Multiple collinear magnetic arrangements in thin Mn films supported on Fe(001). Antiferromagnetic versus ferromagnetic behavior

    International Nuclear Information System (INIS)

    Martinez, E.; Vega, A.; Robles, R.; Vazquez de Parga, A.L.

    2005-01-01

    We present a theoretical study of the magnetic properties of thin Mn films of 6 and 7 monolayers supported on Fe(001). The ab-initio tight binding linear muffin tin orbital (TB-LMTO) method was used to investigate the competition between ferromagnetic (F) and antiferromagnetic (AF) couplings within the system. We found several collinear magnetic solutions that may coexist at room temperature. The most stable configurations are characterized by AF coupling between the surface and subsurface Mn layers together with F coupling between Mn and Fe at the interface. The ground state arrangements for the 6 and 7 Mn films display opposite sign of the surface magnetic moment relative to the Fe substrate. The implications of these results in the possible onset of non-collinear magnetism when a step is present at the interface are discussed in comparison with Cr/Fe systems where non-collinear magnetism has been recently reported

  12. Synthesis and electronic properties of Fe2TiO5 epitaxial thin films

    Science.gov (United States)

    Osada, Motoki; Nishio, Kazunori; Hwang, Harold Y.; Hikita, Yasuyuki

    2018-05-01

    We investigate the growth phase diagram of pseudobrookite Fe2TiO5 epitaxial thin films on LaAlO3 (001) substrates using pulsed laser deposition. Control of the oxygen partial pressure and temperature during deposition enabled selective stabilization of (100)- and (230)-oriented films. In this regime, we find an optical gap of 2.1 eV and room temperature resistivity in the range of 20-80 Ω cm, which are significantly lower than α-Fe2O3, making Fe2TiO5 potentially an ideal inexpensive visible-light harvesting semiconductor. These results provide a basis to incorporate Fe2TiO5 in oxide heterostructures for photocatalytic and photoelectrochemical applications.

  13. Zn Thin Film Deposition for Fe Layer Shielding Use the Sputtering Technique on Cylindrical Form

    International Nuclear Information System (INIS)

    Yunanto; Tjipto Sujitno, BA; Suprapto; Simbolon, Sahat

    2002-01-01

    Deposition of thin film on Fe substrate use sputtering technique on cylindrical form was carried out. The purpose of this research is to protect Fe due to the corrosion with Zn thin film. Sputtering method was proposed to protect a component of complex form. Substrate has functioned as anode, meanwhile target in cylindrical form as a cathode. Argon ion from anode bombard Zn with enough energy for releasing Zn. Zn atom would scatter and some of then was focused on the anode. For testing Zn atom on Fe by using XRF and corrosion rate with potentiostat. It was found that corrosion rate was decreased from 0.051 mpy to 0.031 mpy on 0.63 % of Fe substrate. (author)

  14. Electrical, thermal and magnetic behaviour of the metallic glass Fe80B20 in the crystallization process

    International Nuclear Information System (INIS)

    Isalgue, A.; Cusido, J.A.

    1986-01-01

    The thermal, electrical DC conductivity and magnetic properties have been studied in the crystallization process of the metallic glass Fe 80 B 20 (Metglass 2605) induced by heat treatment. The electrical and thermal conductivity, the coercive force and the remanence are strongly affected with the crystallization of the glass. Two steps can be dicerned from the magnetic measurements; the differences between the two steps are interpreted in the basis of the ''spherulite-type'', grown of Fe 3 B in the first crystallization step and the aparition of Fe 2 B in the second step. (author)

  15. Effect of heat treatment on interface driven magnetic properties of CoFe films

    Science.gov (United States)

    Singh, Akhilesh Kr.; Hsu, Jen-Hwa

    2017-06-01

    We report systematic studies on non-magnetic Ta underlayer and cap layer driven microstructural and magnetic properties at a wide temperature range for CoFe films. All the films were grown at room temperature and post annealed at different annealing temperatures (TA = 200 °C, 250 °C, 300 °C, 350 °C, 400 °C and 450 °C). The in-plane magnetic hysteresis (M-H) loops of 10 nm thick CoFe single layer films, grown directly on thermally oxidized Si substrate, exhibit anisotropic nature for TA above 250 °C. However, the CoFe (10 nm) films grown on the 5 nm thick Ta underlayer show reduced anisotropy. Moreover, with underlayer and cap layers (2 nm) the anisotropy is disappeared. The in-plane coercivity (HC) shows a strong variation with TA, underlayer and cap layers. HC increases significantly with Ta underlayer and cap layers. The out of plane M-H loops exhibit increase in the remanence magnetization and squareness with both Ta underlayer and cap layers due to transition of in-plane magnetization component to the out of plane direction. The atomic force microscopic observations revealed that grain/particle size and shape depend strongly on TA and Ta layers. Moreover, a large reduction in the surface roughness is observed with the Ta cap layer. The magnetic domain patterns depend on the TA, and Ta layers. However, for Ta/CoFe/Ta films no clear domains were observed for all the TA. Hence, the Ta cap layers not only protect the CoFe magnetic layer against the heat treatment, but also show a smooth surface at a wide temperature range. These results could be discussed on the basis of random anisotropy model, TA, underlayer and cap layers driven microstructure and magnetization orientation of the CoFe films.

  16. Effect of crystal alignment on the remanence of sintered NdFeB magnets

    International Nuclear Information System (INIS)

    Kawai, T.; Ma, B.M.; Sankar, S.G.; Wallace, W.E.

    1990-01-01

    Nd 15.4 Fe 77.8 B 6.8 magnets of various degrees of crystal alignment have been prepared by the conventional powder metallurgy technique. The alignment of these magnets have been determined by x-ray diffraction and fitting the standard deviation of a Gaussian distribution for the relative intensity versus the angle between the normals of (hkl) and the tetragonal c axis. The standard deviation is a good indicator for crystal alignment. An aligning field of 8 kOe is found to be essential to obtain a well-aligned NdFeB magnet. The remanence of sintered magnets is directly affected by the crystal alignment. Furthermore, the effect of crystal alignment on the remanence follows the theoretical prediction of the Stoner--Wohlfarth model. Below the spin reorientation temperature, the effect of crystal alignment on the shape of hysteresis loop becomes more significant. The remanences extrapolated from first and second quadrant of the hysteresis loops have been found to be consistent with the prediction of Stoner--Wohlfarth model

  17. Additive to regulate the perovskite crystal film growth in planar heterojunction solar cells

    International Nuclear Information System (INIS)

    Song, Xin; Sun, Po; Chen, Zhi-Kuan; Wang, Weiwei; Ma, Wanli

    2015-01-01

    We reported a planar heterojunction perovskite solar cell fabricated from MAPbI 3−x Cl x perovskite precursor solution containing 1-chloronaphthalene (CN) additive. The MAPbI 3−x Cl x perovskite films have been characterized by UV-vis, SEM, XRD, and steady-state photoluminescence (PL). UV-vis absorption spectra measurement shows that the absorbance of the film with CN additive is significantly higher than the pristine film and the absorption peak is red shift by 30 nm, indicating the perovskite film with additive possessing better crystal structures. In-situ XRD study of the perovskite films with additive demonstrated intense diffraction peaks from MAPbI 3−x Cl x perovskite crystal planes of (110), (220), and (330). SEM images of the films with additive indicated the films were more smooth and homogenous with fewer pin-holes and voids and better surface coverage than the pristine films. These results implied that the additive CN is beneficial to regulate the crystallization transformation kinetics of perovskite to form high quality crystal films. The steady-state PL measurement suggested that the films with additive contained less charge traps and defects. The planar heterojunction perovskite solar cells fabricated from perovskite precursor solution containing CN additive demonstrated 30% enhancement in performance compared to the devices with pristine films. The improvement in device efficiency is mainly attributed to the good crystal structures, more homogenous film morphology, and also fewer trap centers and defects in the films with the additive

  18. Analysis of thin-film photonic crystal microstructures

    International Nuclear Information System (INIS)

    Pottage, John Mark

    2003-01-01

    Optical-scale microstructures containing thin-film photonic crystals (TFPCs) are modelled by transfer/scattering matrix methods, based on Fourier-series expansion of the optical Bloch eigenmodes. The majority of the TFPCs considered consist of 2D arrays of holes arranged in a triangular lattice, etched into high-index Al x Ga 1-x As and placed on a low-index oxidised substrate. These TFPCs can be easily fabricated by standard electron-beam lithography techniques. Unlike most photonic crystal devices that have been proposed, our 'intra-pass-band' TFPCs would work by exploiting the somewhat surprising properties of propagating optical Bloch waves rather than directly relying on photonic bandgaps. By numerical modelling, it is demonstrated that 2D-patterned TFPCs can support highly dispersive high-Q quasi-guided and truly-guided resonant modes, and the unusual properties of these modes are explained in terms of their Bloch-wave compositions. Modal dispersion diagrams of TFPCs, showing the loci of the resonant modes in in-plane wavevector space at fixed frequency, are calculated. These so-called 'resonance diagrams' and variants thereof, are shown to be a useful design tool for TFPC-based integrated optical components. It is suggested that TFPCs may be a viable alternative to distributed Bragg reflectors in semiconductor vertical cavity surface-emitting lasers, possessing potential advantages in terms of compactness and ease of fabrication. The high angular and spectral dispersion of the resonant modes implies that TFPCs could form the basis of a new family of compact devices for performing such functions as wavelength-division multiplexing/demultiplexing, beam-steering and frequency-selective filtering. Enhancement of nonlinear effects could also be achieved in TFPC resonators, because in them a high cavity Q-factor and a low in-plane group-velocity can be attained simultaneously. (author)

  19. Ferrite Nanoparticles, Films, Single Crystals, and Metamaterials: High Frequency Applications

    International Nuclear Information System (INIS)

    Harris, V.

    2006-01-01

    Ferrite materials have long played an important role in power conditioning, conversion, and generation across a wide spectrum of frequencies (up to ten decades). They remain the preferred magnetic materials, having suitably low losses, for most applications above 1 MHz, and are the only viable materials for nonreciprocal magnetic microwave and millimeter-wave devices (including tunable filters, isolators, phase shifters, and circulators). Recently, novel processing techniques have led to a resurgence of research interest in the design and processing of ferrite materials as nanoparticles, films, single crystals, and metamaterials. These latest developments have set the stage for their use in emerging technologies that include cancer remediation therapies such as magnetohyperthermia, magnetic targeted drug delivery, and magneto-rheological fluids, as well as enhanced magnetic resonance imaging. With reduced dimensionality of nanoparticles and films, and the inherent nonequilibrium nature of many processing schemes, changes in local chemistry and structure have profound effects on the functional properties and performance of ferrites. In this lecture, we will explore these effects upon the fundamental magnetic and electronic properties of ferrites. Density functional theory will be applied to predict the properties of these ferrites, with synchrotron radiation techniques used to elucidate the chemical and structural short-range order. This approach will be extended to study the atomic design of ferrites by alternating target laser-ablation deposition. Recently, this approach has been shown to produce ferrites that offer attractive properties not found in conventionally grown ferrites. We will explore the latest research developments involving ferrites as related to microwave and millimeter-wave applications and the attempt to integrate these materials with semiconductor materials platforms

  20. Magnetic susceptibility of one-dimensional ferromagnetic CsFeCl3 crystals

    International Nuclear Information System (INIS)

    Tsuboi, T.; Chiba, M.

    1989-01-01

    The parallel and perpendicular magnetic susceptibilities of one-dimensional ferromagnetic CsFeCl 3 crystals have been calculated from magnetization measured as a function of temperature in the range 0 to 70 K by means of a superconducting quantum interference device (SQUID). The experimental results have been compared with data from the literature for other Cs-and Rb-containing crystals with ferromagnetic or antiferromagnetic linear chains. Reliable values of the exchange and anisotropy energies can be estimated from experimental susceptibility data using theoretical g-values and the dynamical correlated-effective field approximation

  1. Connection between twinning and brittle fracture in Fe-Cr-Co-Mo crystals

    International Nuclear Information System (INIS)

    Kirillov, V.A.; Chumlyakov, Yu.I.; Korotaev, A.D.; Aparova, L.A.

    1989-01-01

    Plasticity dependence on crystal orientation, on deformation temperature and structure state of alloy is investigated in Fe-28 % Cr-10 % Co-2 % Mo (at. %) monocrystals. Isostructure decomposition results in increase of critical shearing stresses τ cr , in change of deformation mechanism from slipping into twinning and abrupt reduction of plasticity. Brittleness - ductility transition is detected in high-stable structure states τ cr >280 MPa. Explanation of plasticity abrupt reduction of high-stable crystals using estimation of change of deformation mechanism and of deforming stress high level is given

  2. Bulk photovoltaic effect in LiTaO3 : Fe crystals

    International Nuclear Information System (INIS)

    Karabekyan, S.I.; Odoulov, S.G.

    1991-01-01

    The bulk photovoltaic effect that arises in non centrosymmetric crystals is determined by the third rank tensor. In this work four independent components of photovoltaic tensor, responsible for 'linear' photovoltaic currents, are measured for the first time for LiTaO 3 : Fe crystals in the range of photon energy from 2.07 to 3.88 eV. The observed correlation of the spectral dependences of β 15 and β 22 components indicates common origin of the transverse photovoltaic currents in this material

  3. Crystallization characteristic and scaling behavior of germanium antimony thin films for phase change memory.

    Science.gov (United States)

    Wu, Weihua; Zhao, Zihan; Shen, Bo; Zhai, Jiwei; Song, Sannian; Song, Zhitang

    2018-04-19

    Amorphous Ge8Sb92 thin films with various thicknesses were deposited by magnetron sputtering. The crystallization kinetics and optical properties of the Ge8Sb92 thin films and related scaling effects were investigated by an in situ thermally induced method and an optical technique. With a decrease in film thickness, the crystallization temperature, crystallization activation energy and data retention ability increased significantly. The changed crystallization behavior may be ascribed to the smaller grain size and larger surface-to-volume ratio as the film thickness decreased. Regardless of whether the state was amorphous or crystalline, the film resistance increased remarkably as the film thickness decreased to 3 nm. The optical band gap calculated from the reflection spectra increases distinctly with a reduction in film thickness. X-ray diffraction patterns confirm that the scaling of the Ge8Sb92 thin film can inhibit the crystallization process and reduce the grain size. The values of exponent indices that were obtained indicate that the crystallization mechanism experiences a series of changes with scaling of the film thickness. The crystallization time was estimated to determine the scaling effect on the phase change speed. The scaling effect on the electrical switching performance of a phase change memory cell was also determined. The current-voltage and resistance-voltage characteristics indicate that phase change memory cells based on a thinner Ge8Sb92 film will exhibit a higher threshold voltage, lower RESET operational voltage and greater pulse width, which implies higher thermal stability, lower power consumption and relatively lower switching velocity.

  4. Optical fiber magnetic field sensors with TbDyFe magnetostrictive thin films as sensing materials.

    Science.gov (United States)

    Yang, Minghong; Dai, Jixiang; Zhou, Ciming; Jiang, Desheng

    2009-11-09

    Different from usually-used bulk magnetostrictive materials, magnetostrictive TbDyFe thin films were firstly proposed as sensing materials for fiber-optic magnetic field sensing characterization. By magnetron sputtering process, TbDyFe thin films were deposited on etched side circle of a fiber Bragg Grating (FBG) as sensing element. There exists more than 45pm change of FBG wavelength when magnet field increase up to 50 mT. The response to magnetic field is reversible, and could be applicable for magnetic and current sensing.

  5. Photovoltaic effect in transition metal modified polycrystalline BiFeO3 thin films

    International Nuclear Information System (INIS)

    Puli, Venkata Sreenivas; Chrisey, Douglas B; Pradhan, Dhiren Kumar; Katiyar, Rajesh Kumar; Misra, Pankaj; Scott, J F; Katiyar, Ram S; Coondoo, Indrani; Panwar, Neeraj

    2014-01-01

    We report photovoltaic (PV) effect in multiferroic Bi 0.9 Sm 0.1 Fe 0.95 Co 0.05 O 3 (BSFCO) thin films. Transition metal modified polycrystalline BiFeO 3 (BFO) thin films have been deposited on Pt/TiO 2 /SiO 2 /Si substrate successfully through pulsed laser deposition (PLD). PV response is observed under illumination both in sandwich and lateral electrode configurations. The open-circuit voltage (V oc ) and the short-circuit current density (J sc ) of the films in sandwich electrode configuration under illumination are measured to be 0.9 V and −0.051 µA cm −2 . Additionally, we report piezoresponse for BSFCO films, which confirms ferroelectric piezoelectric behaviour. (paper)

  6. High-coercivity FePt nanoparticle assemblies embedded in silica thin films

    International Nuclear Information System (INIS)

    Yan, Q; Purkayastha, A; Singh, A P; Li, H; Ramanath, G; Li, A; Ramanujan, R V

    2009-01-01

    The ability to process assemblies using thin film techniques in a scalable fashion would be a key to transmuting the assemblies into manufacturable devices. Here, we embed FePt nanoparticle assemblies into a silica thin film by sol-gel processing. Annealing the thin film composite at 650 deg. C transforms the chemically disordered fcc FePt phase into the fct phase, yielding magnetic coercivity values H c >630 mT. The positional order of the particles is retained due to the protection offered by the silica host. Such films with assemblies of high-coercivity magnetic particles are attractive for realizing new types of ultra-high-density data storage devices and magneto-composites.

  7. Strain Effect on Electronic Structure and Work Function in α-Fe2O3 Films

    Directory of Open Access Journals (Sweden)

    Li Chen

    2017-03-01

    Full Text Available We investigate the electronic structure and work function modulation of α-Fe2O3 films by strain based on the density functional method. We find that the band gap of clean α-Fe2O3 films is a function of the strain and is influenced significantly by the element termination on the surface. The px and py orbitals keep close to Fermi level and account for a pronounced narrowing band gap under compressive strain, while unoccupied dz2 orbitals from conduction band minimum draw nearer to Fermi level and are responsible for the pronounced narrowing band gap under tensile strain. The spin polarized surface state, arising from localized dangling-bond states, is insensitive to strain, while the bulk band, especially for pz orbital, arising from extended Bloch states, is very sensitive to strain, which plays an important role for work function decreasing (increasing under compressive (tensile strain in Fe termination films. In particular, the work function in O terminated films is insensitive to strain because pz orbitals are less sensitive to strain than that of Fe termination films. Our findings confirm that the strain is an effective means to manipulate electronic structures and corrosion potential.

  8. Electric and Magnetic Properties of Sputter Deposited BiFeO3 Films

    Directory of Open Access Journals (Sweden)

    N. Siadou

    2013-01-01

    Full Text Available Polycrystalline BiFeO3 films have been magnetron sputter deposited at room temperature and subsequently heat-treated ex situ at temperatures between 400 and 700°C. The deposition was done in pure Ar atmosphere, as the use of oxygen-argon mixture was found to lead to nonstoichiometric films due to resputtering effects. At a target-to-substrate distance d=2′′ the BiFeO3 structure can be obtained in larger range process gas pressures (2–7 mTorr but the films do not show a specific texture. At d=6′′ codeposition from BiFeO3 and Bi2O3 has been used. Films sputtered at low rate tend to grow with the (001 texture of the pseudo-cubic BiFeO3 structure. As the film structure does not depend on epitaxy similar results are obtained on different substrates. A result of the volatility of Bi, Bi rich oxide phases occur after heat treatment at high temperatures. A Bi2SiO5 impurity phase forms on the substrate side, and does not affect the properties of the main phase. Despite the deposition on amorphous silicon oxide substrate weak ferromagnetism phenomena and displaced loops have been observed at low temperatures showing that their origin is not strain. Ba, La, Ca, and Sr doping suppress the formation of impurity phases and leakage currents.

  9. Magnetic properties and microstructure investigation of electrodeposited FeNi/ITO films with different thickness

    International Nuclear Information System (INIS)

    Cao, Derang; Wang, Zhenkun; Feng, Erxi; Wei, Jinwu; Wang, Jianbo; Liu, Qingfang

    2013-01-01

    Highlights: •FeNi alloy thin films with different thickness deposited on Indium Tin Oxides (ITOs) conductive glass substrates by electrodeposition method. •A columnar crystalline microstructure and domain structure were obtained in FeNi thin films. •Particular FMR spectra of FeNi alloy with different thickness were studied. -- Abstract: FeNi alloy thin films with different thickness deposited on Indium Tin Oxides (ITOs) conductive glass substrates from the electrolytes by electrodeposition method have been studied by magnetic force microscopy (MFM), scanning electron microscopy (SEM) and ferromagnetic resonance (FMR) technique. For these films possessing an in-plane isotropy, the remanence decreases with the increasing of film thickness and the critical thickness that a stripe domain structure emerges is about 116 nm. Characteristic differences of the FMR spectra of different thickness are also observed. The results show that the resonance field at high measured angle increases firstly then decreases with increasing thickness, which may be related to the striped domain structure

  10. Origin of room temperature ferromagnetic moment in Rh-rich [Rh/Fe] multilayer thin films

    International Nuclear Information System (INIS)

    Kande, Dhishan; Laughlin, David; Zhu Jiangang

    2010-01-01

    B2 ordered FeRh thin films switch from antiferromagnetic (AFM) to ferromagnetic (FM) state on heating above 350 K and switch back on cooling, with a hysteresis. This property makes FeRh a very attractive choice as a write-assist layer material for low temperature heat assisted magnetic recording (HAMR) media. Studies have shown that as we decrease the thickness of the FeRh films, the B2 phase is no longer AFM even below 350 K and there is a thickness dependant FM stabilization of the B2 phase. It was also proved that slightly Rh-richer compositions (>50 at. % Rh) were more preferable to stabilize the AFM phase. The current study focuses on growing highly ordered FeRh films by alternate layer rf sputtering of thin layers of iron and rhodium onto a heated substrate. It has been shown that films with rhodium content beyond 55 at. % contain a disordered bcc FM phase which gives rise to residual moment at room temperature even for thicker films.

  11. Ball-milling-induced crystallization and ball-milling effect on thermal crystallization kinetics in an amorphous FeMoSiB alloy

    International Nuclear Information System (INIS)

    Guo, F.Q.; Lu, K.

    1997-01-01

    Microstructure evolution in a melt-spun amorphous Fe 77.2 Mo 0.8 Si 9 B 13 alloy subjected to high-energy ball milling was investigated by means of X-ray diffraction (XRD), a transmission electron microscope (TEM), and a differential scanning calorimeter (DSC). It was found that during ball milling, crystallization occurs in the amorphous ribbon sample with precipitation of an α-Fe solid solution, and the amorphous sample crystallizes completely into a single α-Fe nanostructure (rather than α-Fe and borides as in the usual thermal crystallization products) when the milling time exceeds 135 hours. The volume fraction of material crystallized was found to be approximately proportional to the milling time. The fully crystallized sample with a single α-Fe nanophase exhibits an intrinsic thermal stability against phase separation upon annealing at high temperatures. The ball-milling effect on the subsequent thermal crystallization of the amorphous phase in an as-milled sample was studied by comparison of the crystallization products and kinetic parameters between the as-quenched amorphous sample and the as-milled sample was studied by comparison of the crystallization products and kinetic parameters between the as-quenched amorphous sample and the as-milled partially crystallized samples. The crystallization temperatures and activation energies for the crystallization processes of the residual amorphous phase were considerably decreased due to ball milling, indicating that ball milling has a significant effect on the depression of thermal stability of the residual amorphous phase

  12. Room temperature exchange bias in SmFeO_3 single crystal

    International Nuclear Information System (INIS)

    Wang, Xiaoxiong; Cheng, Xiangyi; Gao, Shang; Song, Junda; Ruan, Keqing; Li, Xiaoguang

    2016-01-01

    Exchange bias phenomenon is generally ascribed to the unidirectional magnetic shift along the field axes at interface of two magnetic materials. Room temperature exchange bias is found in SmFeO_3 single crystal. The behavior after different cooling procedure is regular, and the training behavior is attributed to the athermal training and its pinning origin is attributed to the antiferromagnetic clusters. Its being single phase and occurring at room temperature make it an appropriate candidate for application. - Graphical abstract: Room temperature exchange bias was found in oxide single crystal. Highlights: • Room temperature exchange bias has been discovered in single-crystalline SmFeO_3. • Its pinning origin is attributed to the antiferromagnetic clusters. • Its being single phase and occurring at room temperature make it an appropriate candidate for application.

  13. Paramagnetic resonance and susceptibility of ilmenite, FeTiO3 crystal

    Science.gov (United States)

    Mcdonald, P. F.; Parasiris, A.; Pandey, R. K.; Gries, B. L.; Kirk, W. P.

    1991-01-01

    Large high-purity single crystals of FeTiO3 with ilmenite structure have been grown from a stoichiometric melt of Fe2O3 and TiO2 under an inert atmosphere using the modified Czochralski technique. Susceptibility and X-band paramagnetic resonance studies have been performed. Susceptibility measurements indicate a Neel temperature of about 59 K. The paramagnetic resonance spectrum for magnetic field perpendicular to the crystal c axis consists of a portion of a single, very intense approximately Lorentzian absorption line with its peak at about 600 G and half width at half maximum almost 1200 G. The absorption extends to zero magnetic field. For magnetic field approximately parallel to the c axis, the paramagnetic absorption is much smaller and may be considered a superposition of two approximately Lorentzian line shapes. The magnetic resonance measurements indicate a weak temperature dependence and large angular anisotropy.

  14. Spin-waves in Antiferromagnetic Single-crystal LiFePO4

    International Nuclear Information System (INIS)

    Li, Jiying; Garlea, Vasile O.; Zarestky, Jarel; Vaknin, D.

    2006-01-01

    Spin-wave dispersions in the antiferromagnetic state of single-crystal LiFePO 4 were determined by inelastic neutron scattering measurements. The dispersion curves measured from the (0,1,0) reflection along both a* and b* reciprocal-space directions reflect the anisotropic coupling of the layered Fe 2+ (S=2) spin system. The spin-wave dispersion curves were theoretically modeled using linear spin-wave theory by including in the spin Hamiltonian in-plane nearest- and next-nearest-neighbor interactions (J 1 and J 2 ), inter-plane nearest-neighbor interactions (J(perpendicular)) and a single-ion anisotropy (D). A weak (0,1,0) magnetic peak was observed in elastic neutron scattering studies of the same crystal indicating that the ground state of the staggered iron moments is not along the (0,1,0) direction, as previously reported from polycrystalline samples studies, but slightly rotated away from this axis.

  15. The effect of temperature on the crystallization of α-Fe2O3 particles from dense β-FeOOH suspensions

    International Nuclear Information System (INIS)

    Zic, Mark; Ristic, Mira; Music, Svetozar

    2010-01-01

    The effect of temperature on the crystallization of α-Fe 2 O 3 particles from dense β-FeOOH suspensions was monitored by 57 Fe Moessbauer spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and energy dispersive spectroscopy. Dense suspensions of very long laterally arranged β-FeOOH fibrils were obtained at 90 deg. C. Crystallization at 120 deg. C between 18 and 72 h yielded monodisperse α-Fe 2 O 3 particles of a shape close to that of double spheres with ring. The double spheres with ring showed two narrow particle size distributions. In these particles a substructure was detected, i.e., the spheres consisted of the linear chains of interconnected α-Fe 2 O 3 subparticles. With further rise in the crystallization temperature the increase in α-Fe 2 O 3 particles and porosity became pronounced. Obviously, the aggregation mechanism played an important role in the formation of α-Fe 2 O 3 particles.

  16. A phase transition close to room temperature in BiFeO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kreisel, J; Jadhav, P; Chaix-Pluchery, O [Laboratoire des Materiaux et du Genie Physique, Grenoble INP, CNRS, Minatec, 3, parvis Louis Neel, 38016 Grenoble (France); Varela, M [Departamento Fisica Aplicada i Optica, Universitat de Barcelona, Carrer MartI i Franques 1. 08028 Campus UAB, Bellaterra 08193 (Spain); Dix, N; Sanchez, F; Fontcuberta, J, E-mail: jens.kreisel@grenoble-inp.fr [Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra 08193 (Spain)

    2011-08-31

    BiFeO{sub 3} (BFO) multiferroic oxide has a complex phase diagram that can be mapped by using appropriately substrate-induced strain in epitaxial films. By using Raman spectroscopy, we conclusively show that films of the so-called supertetragonal T-BFO phase, stabilized under compressive strain, display a reversible temperature-induced phase transition at about 100 deg. C, and thus close to room temperature. (fast track communication)

  17. Interaction domains in high-performance NdFeB thick films

    Energy Technology Data Exchange (ETDEWEB)

    Woodcock, T.G. [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany)], E-mail: t.woodcock@ifw-dresden.de; Khlopkov, K. [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany); Walther, A. [Insitut Neel, CNRS-UJF, 25 avenue de Martyrs, 38042 Grenoble (France); CEA Leti - MINATEC, 17 rue des Martyrs, 38054 Grenoble (France); Dempsey, N.M.; Givord, D. [Insitut Neel, CNRS-UJF, 25 avenue de Martyrs, 38042 Grenoble (France); Schultz, L.; Gutfleisch, O. [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany)

    2009-05-15

    The magnetic domain structure in sputtered NdFeB thick films has been imaged by magnetic force microscopy. The local texture of the films was investigated by electron backscatter diffraction. The average misorientation of the grains was shown to decrease with increasing substrate temperature during deposition. Interaction domains were observed and are discussed with reference (i) to the sample grain size compared to the single domain particle size and (ii) to sample texture.

  18. Field-angle dependence of magnetic resonance in Pt/NiFe films

    International Nuclear Information System (INIS)

    Inoue, H.Y.; Harii, K.; Saitoh, E.

    2007-01-01

    Ferromagnetic resonance in NiFe/ amorphous Pt bilayer thin films was investigated with changing the external field direction. The spectral width of the ferromagnetic resonance depends critically on the external-magnetic-field direction. We found that the sample dependence of the spectral width is enhanced with deviation of external field direction from the direction along the film plain, implying an important role of spin directions in field-induced spin-decoherence mechanism in Pt

  19. Effects of quartz on crystallization behavior of mold fluxes and microstructural characteristics of flux film.

    Science.gov (United States)

    Lei, Liu; Xiuli, Han; Mingduo, Li; Di, Zhang

    2018-01-01

    Mold fluxes are mainly prepared using cement clinker, quartz, wollastonite, borax, fluorite, soda ash and other mineral materials. Quartz, as one of the most common and essential materials, was chosen for this study to analyze itseffects on crystallization temperature, critical cooling rate, crystal incubation time, crystallization ratio and phases of flux film. We used the research methods of process mineralogy with the application of the single hot thermocouple technique, heat flux simulator, polarizing microscope, X-ray diffraction, etc. Results: By increasing the quartz content from 16 mass% to 24 mass%, the crystallization temperature, critical cooling rate and crystallization ratio of flux film decreased, and the crystal incubation time was extended. Meanwhile, the mineralogical structure of the flux film changed, with a large amount of wollastonite precipitation and a significant decrease in the cuspidine content until it reached zero. This showed a steady decline in the heat transfer control capacity of the flux film. The reason for the results above is that, by increasing the quartz content, the silicon-oxygen tetrahedron network structure promoted a rise in viscosity and restrained ion migration, inhibiting crystal nucleation and growth, leading to the weakening of the crystallization and a decline in the crystallization ratio.

  20. Enhancement in (BHmax of PLD-made isotropic Nd-Fe-B thick film magnets deposited on Si substrates

    Directory of Open Access Journals (Sweden)

    M. Nakano

    2017-05-01

    Full Text Available Increase in Nd contents of a PLD-made isotropic Nd-Fe-B thick-film magnet enabled us to enhance the thickness of the film magnet deposited on a Si substrate because the linear expansion coefficient of Nd is an intermediate value between Nd2Fe14B and Si. The large amount of Nd, however, degraded the residual magnetic polarization and (BHmax. In the study, we reduced the Nd contents of each Nd-Fe-B film by inserting a Nd or a Nd-rich Nd-Fe-B buffer layer between a Nd-Fe-B film and a Si substrate in order to suppress the mechanical destruction together with the improvement in magnetic properties. It was found that the mechanical property of a Nd-Fe-B film comprising the Nd-Fe-B buffer layer in the thickness range from 10 to 60 μm was superior than that of a sample with the Nd buffer layer. Resultantly, an average (BHmax value of Nd-Fe-B films with each Nd-Fe-B buffer layer deposited on Si substrates could be enhanced by approximately 15 kJ/m3 compared to that of non-buffer-layered films.

  1. Magneto-optical properties of BiFeO3 thin films using surface plasmon resonance technique

    International Nuclear Information System (INIS)

    Paliwal, Ayushi; Sharma, Anjali; Tomar, Monika; Gupta, Vinay

    2014-01-01

    Indigeneously assembled surface plasmon resonance (SPR) set up has been exploited to study the magnetic field dependent optical properties of BiFeO 3 thin films. BiFeO 3 thin films have been deposited onto gold (Au) coated glass prism by using pulsed laser deposition technique. The surface plasmon modes in prism/Au/BiFeO 3 /air structure have been excited in Kretschmann configuration at the interface of Au/BiFeO 3 thin films. The SPR reflectance curves obtained for prism/Au/BiFeO 3 /air structure were utilized to investigate the optical properties of BiFeO 3 thin films at optical frequency (λ=633 nm) as a function of applied magnetic field. SPR curves shows a continuous shift towards lower angles with increasing applied magnetic field, which indicate the promising application of ferromagnetic BiFeO 3 film as a magnetic field sensor. Complex dielectric constant of deposited BiFeO 3 film was determined by fitting the experimental SPR data with Fresnel's equations. The variation of complex dielectric constant and refractive index of BiFeO 3 film was studied with increase in magnetic field, and the sensitivity of magnetic field sensor was found to be about 0.52 RIU/T

  2. Magneto-optical properties of BiFeO{sub 3} thin films using surface plasmon resonance technique

    Energy Technology Data Exchange (ETDEWEB)

    Paliwal, Ayushi; Sharma, Anjali [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Tomar, Monika [Physics Department, Miranda House, University of Delhi, Delhi 110007 (India); Gupta, Vinay, E-mail: drguptavinay@gmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

    2014-09-01

    Indigeneously assembled surface plasmon resonance (SPR) set up has been exploited to study the magnetic field dependent optical properties of BiFeO{sub 3} thin films. BiFeO{sub 3} thin films have been deposited onto gold (Au) coated glass prism by using pulsed laser deposition technique. The surface plasmon modes in prism/Au/BiFeO{sub 3}/air structure have been excited in Kretschmann configuration at the interface of Au/BiFeO{sub 3} thin films. The SPR reflectance curves obtained for prism/Au/BiFeO{sub 3}/air structure were utilized to investigate the optical properties of BiFeO{sub 3} thin films at optical frequency (λ=633 nm) as a function of applied magnetic field. SPR curves shows a continuous shift towards lower angles with increasing applied magnetic field, which indicate the promising application of ferromagnetic BiFeO{sub 3} film as a magnetic field sensor. Complex dielectric constant of deposited BiFeO{sub 3} film was determined by fitting the experimental SPR data with Fresnel's equations. The variation of complex dielectric constant and refractive index of BiFeO{sub 3} film was studied with increase in magnetic field, and the sensitivity of magnetic field sensor was found to be about 0.52 RIU/T.

  3. Solution Coating of Superior Large-Area Flexible Perovskite Thin Films with Controlled Crystal Packing

    KAUST Repository

    Li, Jianbo

    2017-05-08

    Solution coating of organohalide lead perovskites offers great potential for achieving low-cost manufacturing of large-area flexible optoelectronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of crystal packing. Herein, this study reports using solution shearing to confine crystal nucleation and growth in large-area printed MAPbI3 thin films. Near single-crystalline perovskite microarrays are demonstrated with a high degree of controlled macroscopic alignment and crystal orientation, which exhibit significant improvements in optical and optoelectronic properties comparing with their random counterparts, spherulitic, and nanograined films. In particular, photodetectors based on the confined films showing intense anisotropy in charge transport are fabricated, and the device exhibits significantly improved performance in all aspects by one more orders of magnitude relative to their random counterparts. It is anticipated that perovskite films with controlled crystal packing may find applications in high-performance, large-area printed optoelectronics, and solar cells.

  4. Solution Coating of Superior Large-Area Flexible Perovskite Thin Films with Controlled Crystal Packing

    KAUST Repository

    Li, Jianbo; Liu, Yucheng; Ren, Xiaodong; Yang, Zhou; Li, Ruipeng; Su, Hang; Yang, Xiaoming; Xu, Junzhuo; Xu, Hua; Hu, Jian-Yong; Amassian, Aram; Zhao, Kui; Liu, Shengzhong Frank

    2017-01-01

    Solution coating of organohalide lead perovskites offers great potential for achieving low-cost manufacturing of large-area flexible optoelectronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of crystal packing. Herein, this study reports using solution shearing to confine crystal nucleation and growth in large-area printed MAPbI3 thin films. Near single-crystalline perovskite microarrays are demonstrated with a high degree of controlled macroscopic alignment and crystal orientation, which exhibit significant improvements in optical and optoelectronic properties comparing with their random counterparts, spherulitic, and nanograined films. In particular, photodetectors based on the confined films showing intense anisotropy in charge transport are fabricated, and the device exhibits significantly improved performance in all aspects by one more orders of magnitude relative to their random counterparts. It is anticipated that perovskite films with controlled crystal packing may find applications in high-performance, large-area printed optoelectronics, and solar cells.

  5. Moessbauer diffraction study of the Neel phase transition in Fe3BO6 crystal

    International Nuclear Information System (INIS)

    Kovalenko, P.P.; Labushkin, V.G.; Sarkisov, Eh.R.; Tolpekin, I.G.

    1987-01-01

    Phase transitions in a 57 Fe 3 BO 6 monocrystal in the vicinity of the Neel point, T N =507.5 K were investigated by means of the Moessbauergraphy. For the first time the relaxation type of Moessbauer spectra was observed near the phase transition point. First in the Moessbauer diffraction spectrum of the crystal the simultaneous presence of a component resulted from magnetic ordering and a paramagnetic component was observed

  6. Temperature-dependent magnetism of Fe thin films on ZnSe(0 0 1)

    International Nuclear Information System (INIS)

    Cantoni, M.; Bertacco, R.; Ciccacci, F.; Puppin, E.; Pinotti, E.; Brenna, M.; Marangolo, M.; Eddrieff, M.; Torelli, P.; Maccherozzi, F.; Fujii, J.; Panaccione, G.

    2007-01-01

    We present X-ray magnetic circular dichroism (XMCD) and magneto-optical Kerr effect (MOKE) data on the magnetic properties of Fe/ZnSe(0 0 1) thin films at increasing Fe coverage. The magnetic behaviour of the Fe overlayer is superparamagnetic for a coverage up to 6 monolayers whereas, above this threshold, a truly ferromagnetic phase shows up. XMCD and MOKE data show that this behaviour is substantially unchanged in the temperature range 10-300 K for all the investigated coverages: these findings imply that the blocking temperature is definitely below 10 K

  7. Improved high-frequency soft magnetic properties of FeCo films on organic ferroelectric PVDF substrate

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dong; Wang, Zhen; Han, Xuemeng; Li, Yue; Guo, Xiaobin; Zuo, Yalu; Xi, Li, E-mail: xili@lzu.edu.cn

    2015-02-01

    FeCo films with various thicknesses were fabricated by direct-current magnetron sputtering on corning glass and organic ferroelectric PVDF substrates at the same time with 5 nm Ru seed layer and 5 nm Ta protective layer. The in-plane uniaxial anisotropy field of FeCo on glass substrate increases from 24 to 36 Oe with the increase of FeCo film thickness from 5 to 100 nm. However, a large in-plane anisotropy field of FeCo on PVDF substrate increases with FeCo thickness from 5 to 20 nm and gradually decreases with the FeCo thickness further increasing. Atomic force microscope images of FeCo on glass show quite smooth surface with root-mean-square roughness around 0.5 nm and have none visible granules on the surface for all samples. While, AFM images of FeCo on PVDF show quite rough surface with RMS roughness around 25 nm and have visible granules with the smallest granules appearing at the FeCo thickness of 20 nm. The permeability spectra show the typical ferromagnetic resonance phenomenon and can be well fitted by the LLG equation with the obtained experimental parameters. The ferromagnetic resonance frequency can reach 7.0 GHz for the 20 nm FeCo film on PVDF. Moreover, the quality factor of this sample can respectively reach 26, 12 and 7 at 1.0, 2.0, and 3.0 GHz, indicating the potential real 3G application for high-frequency devices. - Highlights: 1.Magnetic and morphological properties of FeCo films on PVDF substrates are studied. 2.The large anisotropy field of FeCo films on PVDF is obtained. 3.Improved high frequency properties of FeCo films on flexible substrates are obtained. 4.The origin of improved high frequency properties of FeCo films on PVDF is studied.

  8. Parylene-C microfibrous thin films as phononic crystals

    Science.gov (United States)

    Chindam, Chandraprakash; Lakhtakia, Akhlesh; Awadelkarim, Osama O.

    2017-07-01

    Phononic bandgaps of Parylene-C microfibrous thin films ( μ\\text{FTF} s) were computationally determined by treating them as phononic crystals comprising identical microfibers arranged either on a square or a hexagonal lattice. The microfibers could be columnar, chevronic, or helical in shape, and the host medium could be either water or air. All bandgaps were observed to lie in the 0.01-162.9-MHz regime, for microfibers of realistically chosen dimensions. The upper limit of the frequency of bandgaps was the highest for the columnar μ\\text{FTF} and the lowest for the chiral μ\\text{FTF} . More bandgaps exist when the host medium is water than air. Complete bandgaps were observed for the columnar μ\\text{FTF} with microfibers arranged on a hexagonal lattice in air, the chevronic μ\\text{FTF} with microfibers arranged on a square lattice in water, and the chiral μ\\text{FTF} with microfibers arranged on a hexagonal lattice in either air or water. The softness of the Parylene-C μ\\text{FTF} s makes them mechanically tunable, and their bandgaps can be exploited in multiband ultrasonic filters.

  9. Effect of the Ultrasonic Substrate Vibration on Nucleation and Crystallization of PbI2 Crystals and Thin Films

    Directory of Open Access Journals (Sweden)

    Fatemeh Zabihi

    2018-01-01

    Full Text Available Preparation of defect-free and well-controlled solution-processed crystalline thin films is highly desirable for emerging technologies, such as perovskite solar cells. In this work, using PbI2 as a model solution with a vast variety of applications, we demonstrate that the excitation of a liquid thin film by imposed ultrasonic vibration on the film substrate significantly affects the nucleation and crystallization kinetics of PbI2 and the morphology of the resulting solid thin film. It is found that by applying ultrasonic vibration to PbI2 solution spun onto an ITO substrate with a moderate power and excitation duration (5 W and 1 min for the 40 kHz transducer used in this study, the nucleation rate increases and the crystals transform from 2D or planar to epitaxial 3D columnar structures, resulting in the suppression of crystallization dewetting. The effects of various induced physical phenomena as a result of the excitation by ultrasonic vibration are discussed, including microstreaming and micromixing, increased heat transfer and local temperature, a change in the thermodynamic state of the solution, and a decrease in the supersaturation point. It is shown that the ultrasonic-assisted solution deposition of the PbI2 thin films is controllable and reproducible, a process which is low-cost and in line with the large-scale fabrication of such solution-processed thin films.

  10. Soft magnetic properties and damping parameter of (FeCo-Al alloy thin films

    Directory of Open Access Journals (Sweden)

    Isao Kanada

    2017-05-01

    Full Text Available For high frequency device applications, a systematic study of the soft magnetic properties and magnetization dynamics of (FeCo-Al alloy thin films has been carried out. A low effective damping parameter αeff of 0.002 and a high saturation magnetization of about 1,800 emu/cc are obtained at y=0.2∼0.3 for (Fe1-yCoy98Al2 alloy thin films deposited onto fused silica and MgO(100 at an ambient temperature during deposition. Those films are of the bcc structure with the orientation normal to the film plane. They possess a columnar structure, grown along the film normal. The column width is found to be about 20 nm for y=0.25. It is concluded that the (FeCo-Al thin films with a damping parameter as low as 0.002 and high saturation magnetization of about 1,800 emu/cc have been successfully fabricated, and that they are potential for future high frequency device applications.

  11. Organic Single-Crystal Semiconductor Films on a Millimeter Domain Scale.

    Science.gov (United States)

    Kwon, Sooncheol; Kim, Jehan; Kim, Geunjin; Yu, Kilho; Jo, Yong-Ryun; Kim, Bong-Joong; Kim, Junghwan; Kang, Hongkyu; Park, Byoungwook; Lee, Kwanghee

    2015-11-18

    Nucleation and growth processes can be effectively controlled in organic semiconductor films through a new concept of template-mediated molecular crystal seeds during the phase transition; the effective control of these processes ensures millimeter-scale crystal domains, as well as the performance of the resulting organic films with intrinsic hole mobility of 18 cm(2) V(-1) s(-1). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Crystal structure and electrical resistivity studies of Gd(Fe1-x Cox)2 intermetallics

    International Nuclear Information System (INIS)

    Onak, M.; Guzdek, P.; Stoch, P.; Chmist, J.; Bednarski, M.; Panta, A.; Pszczola, J.

    2007-01-01

    From X-ray analysis (295 K) it was found that the cubic, MgCu 2 -type, Fd3m crystal structure appears across the Gd(Fe 1-x Co x ) 2 series. Electrical resistivity measurements for the Gd(Fe 1-x Co x ) 2 intermetallics were performed in a wide temperature region and the parameters characterizing the resistivity dependence on temperature and composition were determined. The differential of the electrical resistivity against temperature was used to estimate Curie temperatures. The Curie temperature versus x, high and moderately increasing in the iron-rich area, rapidly drops in the cobalt-rich region. The obtained results are compared with the data known for the Dy(Fe 1-x Co x ) 2 series. The Curie temperature is related to both the number of 3d electrons and the de Gennes factor

  13. Magnetocrystalline two-fold symmetry in CaFe2O4 single crystal

    International Nuclear Information System (INIS)

    Gandhi, Ashish Chhaganlal; Das, Rajasree; Chou, Fang-Cheng; Lin, Jauyn Grace

    2017-01-01

    Understanding of magnetocrystalline anisotropy in CaFe 2 O 4 is a matter of importance for its future applications. A high quality single crystal CaFe 2 O 4 sample is studied by using synchrotron x-ray diffraction, a magnetometer and the electron spin resonance (ESR) technique. A broad feature of the susceptibility curve around room temperature is observed, indicating the development of 1D spin interactions above the on-set of antiferromagnetic transition. The angular dependency of ESR reveals an in-plane two-fold symmetry, suggesting a strong correlation between the room temperature spin structure and magnetocrystalline anisotropy. This finding opens an opportunity for the device utilizing the anisotropy field of CaFe 2 O 4 . (paper)

  14. Magnetocrystalline two-fold symmetry in CaFe2O4 single crystal

    Science.gov (United States)

    Chhaganlal Gandhi, Ashish; Das, Rajasree; Chou, Fang-Cheng; Lin, Jauyn Grace

    2017-05-01

    Understanding of magnetocrystalline anisotropy in CaFe2O4 is a matter of importance for its future applications. A high quality single crystal CaFe2O4 sample is studied by using synchrotron x-ray diffraction, a magnetometer and the electron spin resonance (ESR) technique. A broad feature of the susceptibility curve around room temperature is observed, indicating the development of 1D spin interactions above the on-set of antiferromagnetic transition. The angular dependency of ESR reveals an in-plane two-fold symmetry, suggesting a strong correlation between the room temperature spin structure and magnetocrystalline anisotropy. This finding opens an opportunity for the device utilizing the anisotropy field of CaFe2O4.

  15. X-ray magnetic absorption in Fe-Tb amorphous thin films

    CERN Document Server

    Kim, Chan Wook; Watanabe, Yasuhiro

    1999-01-01

    In order to investigate the magnetic structure of Fe-Tb amorphous thin films, we have performed magnetic circular dichroism (MCD) measurements by using the circularly polarized X-ray at the Fe K- and the Tb L2,3-edges in Fe sub 8 sub 8 Tb sub 1 sub 2 , Fe sub 8 sub 0 Tb sub 2 sub 0 , and Fe sub 6 sub 2 Tb sub 3 sub 8. In all samples, the spin-dependent absorption effects, DELTA mu t, were observed. Also, elementary information was obtained on the spin polarizations of the p- and the d-projected electrons lying in the unoccupied states near the Fermi levels in the samples.

  16. The temperature dependence of magnetic anisotropy of Nd-Fe-B thin films

    Science.gov (United States)

    Sato, Takuya; Hashimoto, Ryuji; Tanaka, Yoshitomo; Suzuki, Kenichi; Enokido, Yasushi; Choi, Kyung-Ku; Suzuki, Takao

    2018-05-01

    The magnetic properties of Nd-Fe-B thin films with the three different compositions (#1: Nd12.6Fe81.5B5.9, #2: Nd14.6Fe78.1B7.4 and #3: Nd22.6Fe66.2B11.2) are discussed. With increasing Nd content, the c-axis orientation along the film normal is enhanced. It is found that sample #2 possesses the saturation magnetization Ms very close to that for Nd2Fe14B over a temperature range from 100 to about 300K. The magnetic anisotropy constant Ku2 for sample #2 is the highest among those samples, but smaller by about 20%, as compared to that for Nd2Fe14B. It is of interest to note that the temperature TR at which Ku1 changes its sign is lower by about 30K as compared to that previously reported for Nd2Fe14B. The reason for this discrepancy is not clear, but could be due to the presence of the minority phases of Nd-rich compounds and also a possible contribution of the magneto-elastic effect to the net magnetic anisotropy.

  17. In-situ investigation of the icosahedral Al-Cu-Fe phase formation in thin films

    Energy Technology Data Exchange (ETDEWEB)

    Haidara, F., E-mail: fanta.haidara@im2np.fr [IM2NP, UMR 6242 CNRS - Universite Aix-Marseille, Av. Escadrille Normandie-Niemen, Case 142, 13397 Marseille Cedex 20 (France); Duployer, B. [Universite Paul Sabatier CIRIMAT-LCMIE 2R1, 118, Route de Narbonne, 31062 Toulouse Cedex 09 (France); Mangelinck, D.; Record, M.-C. [IM2NP, UMR 6242 CNRS - Universite Aix-Marseille, Av. Escadrille Normandie-Niemen, Case 142, 13397 Marseille Cedex 20 (France)

    2012-09-05

    Highlights: Black-Right-Pointing-Pointer We investigated the phase formation of i-Al{sub 62.5}Cu{sub 25}Fe{sub 12.5} in thin films. Black-Right-Pointing-Pointer We characterized the samples by DSC and in-situ XRD and resistance measurements. Black-Right-Pointing-Pointer The resistivity value for i-Al{sub 62.5}Cu{sub 25}Fe{sub 12.5} was determined. - Abstract: This work is an investigation of the formation by reactive diffusion at high temperatures of the icosahedral phase, i-Al{sub 62.5}Cu{sub 25}Fe{sub 12.5}, in thin films. The samples were prepared by sputtering at room temperature. The elements Al, Cu and Fe were sequentially deposited onto oxidized silicon substrates. The two following stacking sequences, Al/Cu/Fe and Al/Fe/Cu, were investigated. The phase formation was studied using in situ resistivity, in situ X-ray Diffraction and Differential Scanning Calorimetry measurements. Whatever the stacking sequence, the sequences of phase formation evidenced during the heating treatment are similar. However the temperatures of formation for the first phases that are formed are different; they are higher in the case of the Al/Fe/Cu stacking sequence.

  18. Natural gels: crystal-chemistry of short range ordered components in Al, Fe, and Si systems

    International Nuclear Information System (INIS)

    Ildefonse, Ph.; Calas, G.

    1997-01-01

    In this review, the most important inorganic natural gels are presented: opal, aluminosilicate (allophanes) and hydrous iron oxides and silicates. It is demonstrated that natural gels are ordered at the atomic scale. In allophanes, Al is distributed between octahedral and tetrahedral sites. The amount of Al increases as Al/Si ratio decreases. Si-rich allophane have a local structure around Al and Si very different of that is known in kaolinite or halloysite. Transformation of Si-rich allophanes to crystallized minerals implies dissolution-recrystallization processes. On the contrary, in iron silicate with Fe/Si = 0.72, Si and Fe environments are close to those found in nontronite. The gel transformation to Fe-smectite may occur by long range ordering during ageing. In ferric silicate gels, the similarity of local structure around Fe in poorly ordered precursors and what is known in crystallized minerals suggests a solid transformation during ageing. This difference between iron and aluminium is mainly due to the ability of Al to enter both tetrahedral and octahedral sites, while the affinity of iron for octahedral sites is higher at low temperature

  19. The crystal structure of FdxA, a 7Fe ferredoxin from Mycobacterium smegmatis

    International Nuclear Information System (INIS)

    Ricagno, Stefano; De Rosa, Matteo; Aliverti, Alessandro; Zanetti, Giuliana; Bolognesi, Martino

    2007-01-01

    Mycobacterium smegmatis ferredoxin FdxA, which has an orthologue ferredoxin in Mycobacterium tuberculosis, FdxC, contains both one [3Fe-4S] and one [4Fe-4S] cluster. M. smegmatis FdxA has been shown to be a preferred ferredoxin substrate of FprA [F. Fischer, D. Raimondi, A. Aliverti, G. Zanetti, Mycobacterium tuberculosis FprA, a novel bacterial NADPH-ferredoxin reductase, Eur. J. Biochem. 269 (2002) 3005-3013], an adrenodoxin reductase-like flavoprotein of M. tuberculosis, suggesting that M. tuberculosis FdxC could be the physiological partner of the enzyme in providing reducing power to the cytochromes P450. We report here the crystal structure of FdxA at 1.6 A resolution (R factor 16.5%, R free 20.2%). Besides providing an insight on protein architecture for this 106-residue ferredoxin, our crystallographic investigation highlights lability of the [4Fe-4S] center, which is shown to loose a Fe atom during crystal growth. Due to their high similarity (87% sequence identity), the structure here reported can be considered a valuable model for M. tuberculosis FdxC, thus representing a step forward in the study of the complex mycobacterial redox pathways

  20. Study on the Heating Behavior of Fe_3O_4-Embedded Thermoplastic Polyurethane Adhesive Film via Induction heating

    International Nuclear Information System (INIS)

    Bae, Duck Hwan; Shon, Min Young; Oh, Sang Taek; Kim, Gu Ni

    2016-01-01

    The heating behavior of thermoplastic polyurethane adhesive (TPU) embedded by nanometer or micrometer Fe_3O_4 particle is examined by induction heating. The effects of the size and the amount of Fe_3O_4 particle, TPU film thickness, and input power of the induction heater were examined on heating behaviors of TPU. The quantity of heat generated in the TPU films increased with the amount of Fe_3O_4 particles, film thickness, or input power. On the other hand, the quantity of heat generation of TPU is decreased with increasing Fe_3O_4 size. We confirmed that the mechanism of hysteresis led to heat loss in the nanometer and micrometer-sized Fe_3O_4 particles, and it was the key controller of the quantity of heat generated in the Fe_3O_4 particle-embedded TPU films by induction heating.

  1. Biomolecule detection using wheatstone bridge giant magnetoresistance (GMR) sensors based on CoFeB spin-valve thin film

    Science.gov (United States)

    Elda Swastika, P.; Antarnusa, G.; Suharyadi, E.; Kato, T.; Iwata, S.

    2018-04-01

    A potential wheatstone bridge giant magnetoresistance (GMR) biosensor have been successfully developed for biomolecule detection. [IrMn(10 nm)/CoFe(3 nm)/Cu(2.2 nm)/CoFeB(10 nm)] spin-valve structure has been chosen as the magnetic sensing surface, showing a magnetoresistance (MR) of 6% fabricated by DC magnetron sputtering method. The Fe3O4 magnetic nanoparticles used as biomolecular labels (nanotags) was synthesized by co-precipitation method, exhibiting soft magnetic behavior with saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) is 77.2 emu/g, 7.8 emu/g and 51 Oe, respectively. The X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images showed that Fe3O4 was well crystallized and grew in their inverse spinel structure, highly uniform morphology with an average grain size was about 20 nm. Fe3O4 was coated with polyethylene-glycol (PEG)-4000 for surface functionalization. Detection of biomolecule such as formalin, gelatin from bovine-skin and porcine-skin were dispersed in ethanol at room temperature. Induction would cause a shift in output voltage with a minimum delta output voltage (ΔV) 4.937 mV (10%) for formalin detection, 2.268 mV (7%) for bovine-skin gelatin and 2.943 mV (7%) for porcine-skin gelatin detection. The ΔV of the wheatstone bridge in real-time measurement decrease by increase in biomolecules concentration. The change of ΔV with various concentration of biomolecule indicates that the spin-valve thin film with wheatstone-bridge circuit is potential as a biosensor.

  2. Effect of heat treatment on interface driven magnetic properties of CoFe films

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Akhilesh Kr., E-mail: drakhintu@gmail.com; Hsu, Jen-Hwa

    2017-06-15

    Highlights: • Ta underlayer and cap layer dependent anisotropy nature in thin CoFe films. • Thin Ta layer induces the magnetization component along normal to the film plane. • Heat treatment and Ta layers driven surface morphology, roughness and grain size. • Roughness reduces more than an order of magnitude with 2 nm Ta cap layer. • H{sub C}, domain patterns and domain size depend on Ta layers and heat treatment. - Abstract: We report systematic studies on non-magnetic Ta underlayer and cap layer driven microstructural and magnetic properties at a wide temperature range for CoFe films. All the films were grown at room temperature and post annealed at different annealing temperatures (T{sub A} = 200 °C, 250 °C, 300 °C, 350 °C, 400 °C and 450 °C). The in-plane magnetic hysteresis (M–H) loops of 10 nm thick CoFe single layer films, grown directly on thermally oxidized Si substrate, exhibit anisotropic nature for T{sub A} above 250 °C. However, the CoFe (10 nm) films grown on the 5 nm thick Ta underlayer show reduced anisotropy. Moreover, with underlayer and cap layers (2 nm) the anisotropy is disappeared. The in-plane coercivity (H{sub C}) shows a strong variation with T{sub A}, underlayer and cap layers. H{sub C} increases significantly with Ta underlayer and cap layers. The out of plane M–H loops exhibit increase in the remanence magnetization and squareness with both Ta underlayer and cap layers due to transition of in-plane magnetization component to the out of plane direction. The atomic force microscopic observations revealed that grain/particle size and shape depend strongly on T{sub A} and Ta layers. Moreover, a large reduction in the surface roughness is observed with the Ta cap layer. The magnetic domain patterns depend on the T{sub A}, and Ta layers. However, for Ta/CoFe/Ta films no clear domains were observed for all the T{sub A}. Hence, the Ta cap layers not only protect the CoFe magnetic layer against the heat treatment, but also

  3. Effect of heat treatment on interface driven magnetic properties of CoFe films

    International Nuclear Information System (INIS)

    Singh, Akhilesh Kr.; Hsu, Jen-Hwa

    2017-01-01

    Highlights: • Ta underlayer and cap layer dependent anisotropy nature in thin CoFe films. • Thin Ta layer induces the magnetization component along normal to the film plane. • Heat treatment and Ta layers driven surface morphology, roughness and grain size. • Roughness reduces more than an order of magnitude with 2 nm Ta cap layer. • H C , domain patterns and domain size depend on Ta layers and heat treatment. - Abstract: We report systematic studies on non-magnetic Ta underlayer and cap layer driven microstructural and magnetic properties at a wide temperature range for CoFe films. All the films were grown at room temperature and post annealed at different annealing temperatures (T A = 200 °C, 250 °C, 300 °C, 350 °C, 400 °C and 450 °C). The in-plane magnetic hysteresis (M–H) loops of 10 nm thick CoFe single layer films, grown directly on thermally oxidized Si substrate, exhibit anisotropic nature for T A above 250 °C. However, the CoFe (10 nm) films grown on the 5 nm thick Ta underlayer show reduced anisotropy. Moreover, with underlayer and cap layers (2 nm) the anisotropy is disappeared. The in-plane coercivity (H C ) shows a strong variation with T A , underlayer and cap layers. H C increases significantly with Ta underlayer and cap layers. The out of plane M–H loops exhibit increase in the remanence magnetization and squareness with both Ta underlayer and cap layers due to transition of in-plane magnetization component to the out of plane direction. The atomic force microscopic observations revealed that grain/particle size and shape depend strongly on T A and Ta layers. Moreover, a large reduction in the surface roughness is observed with the Ta cap layer. The magnetic domain patterns depend on the T A , and Ta layers. However, for Ta/CoFe/Ta films no clear domains were observed for all the T A . Hence, the Ta cap layers not only protect the CoFe magnetic layer against the heat treatment, but also show a smooth surface at a wide

  4. Temperature driven structural-memory-effects in carbon nanotubes filled with Fe3C nano crystals

    Science.gov (United States)

    Boi, Filippo S.; Zhang, Xiaotian; Corrias, Anna

    2018-02-01

    We report the observation of novel temperature-driven structural-memory-effects in carbon nanotubes (CNTs) filled with Fe3C nano-crystals. These structural-transitions were measured by means of temperature (T) dependent x-ray diffraction (XRD) in the T-range from 298 K to 12 K. A clear reversible 2θ-shift in the 002-peak of the graphitic-CNTs-walls is found with the decrease of the temperature. As determined by Rietveld refinement, such 2θ-shift translates in a not previously reported decrease in the value of the CNT graphitic c-axis with the decrease of the temperature (from 298 K to 12 K). Also, a clear reversible 2θ-shift in the 031 and 131 diffraction-peaks of Fe3C is observed within the same T-range. Rietveld refinements confirm the existence of such memory-effect and also reveal a gradual decrease of the 010-axis of Fe3C with the decrease of the temperature. These observations imply that the observed structural-memory-effect is a characteristic of CNTs when Fe3C is the encapsulated ferromagnet. The generality of such memory-effects was further confirmed by additional measurements performed on other types of CNTs characterized by continuous Fe3C-filling. XRD measurements in the T-range from 298 K to 673 K revealed also an unusual reversible decrease of the Fe3C-peak intensities with the increase of the temperature. These observations can have important implications on the magnetic data recording applications of these nanostructures by helping in better understanding the unusual temperature-dependent magnetic instabilities of iron-based nano-crystals which have been recently reported in literature.

  5. Effect of film roughness in Fe/MgO/Fe magnetic tunnel junctions: model calculations

    Energy Technology Data Exchange (ETDEWEB)

    Edalati Boostan, Saeideh; Heiliger, Christian [I. Physikalisches Institut, Justus Liebig University Giessen, D-35392 (Germany); Moradi, Hosein [Department of Physics,Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

    2011-07-01

    We calculate how interface roughness affects the tunneling magnetoresistance (TMR) in Fe/MgO/Fe (100) junctions. The used method is based on a single-band tight-binding (SBTB) approximation employing the Green's function formalism. We investigate the influence of disorder at the TMR ratio. Thereby, the disorder is modeled by considering different occupation probabilities of Fe and MgO at interface sites. We calculate the current densities for parallel and anti-parallel configurations for different disorders. The results show that the roughness decreases the TMR that match well with experimental observations.

  6. Soft Magnetic Properties of Nanocrystalline Fe-M-(B and/or O)(M=Group IV A, V A Elements) Alloy Films

    OpenAIRE

    Hayakawa, Y.; Makino, A.; Inoue, A.; Masumoto, T.

    1996-01-01

    In Fe-M-(B and/or O)(M=group IV A, V A elements) alloy films, nanocrystalline bcc phase are formed by annealing the amorphous single phase for Fe-M-B films, whereas the bcc nanocrystals are already formed in an as-deposited state for Fe-M-O or Fe-M-B-O) films. Among Fe-M-B films with various M elements, Fe-(Zr, Hf, Nb, Ta)-B alloy films exhibit high saturation magnetization (Is) above 1.4 T and high relative permeability (|μ|) above 1000 at 1MHz. The highest |μ| of 3460 at 1MHz is obtained fo...

  7. Local structural environments of Ge doped in eutectic Sb-Te film before and after crystallization

    Science.gov (United States)

    Shin, Sang Yeol; Cheong, Byung-ki; Choi, Yong Gyu

    2018-06-01

    Electrical phase change device using the Ge-doped eutectic Sb-Te (e.g., Ge1Sb8Te2) film is known to exhibit improved energy efficiency thanks to lowered threshold voltage as well as decreased power consumption for the reset operation, as compared with Ge2Sb2Te5 film. Ge K-edge EXAFS analysis is employed in this study in an effort to elucidate such merits of Ge1Sb8Te2 film in connection with its local atomic arrangements. It is then verified that a Ge atom is four-fold coordinated in its nearest-neighboring shell both in the as-deposited and in the annealed films. It needs to be highlighted that approximately two Sb atoms constitute the Ge tetrahedral units in its amorphous state; however, after being crystallized, heteropolar Ge-Sb bonds hardly exist in this Ge1Sb8Te2 film. It has been known that crystallization temperature and activation energy for crystallization of this Ge1Sb8Te2 composition are greater than those of Ge2Sb2Te5 composition. In addition, these two phase change materials exhibit distinctly different crystallization mechanisms, i.e., nucleation-dominant for Ge2Sb2Te5 film but growth-dominant for Ge1Sb8Te2 film. These discrepancies in the crystallization-related properties are delineated in terms of the local structural changes verified from the present EXAFS analysis.

  8. Optical Properties and Electrochemical Performance of LiFePO4 Thin Films Deposited on Transparent Current Collectors.

    Science.gov (United States)

    Lee, HyunSeok; Yim, Haena; Kim, Kwang-Bum; Choi, Ji-Won

    2015-11-01

    LiFePO4 thin film cathodes are deposited on various transparent conducting oxide thin films on glass, which are used as cathode current collectors. The XRD patterns show that the thin films have the phase of LiFePO4 with an ordered olivine structure indexed to the orthorhombic Pmna space group. LiFePO4 thin film deposited on various TCO glass substrates exhibits transmittance of about 53%. The initial specific discharge capacities of LiFePO4 thin films are 25.0 μAh/cm2 x μm on FTO, 33.0 μAh/cm2 x μm on ITO, and 13.0 μAh/cm2 x μm on AZO coated glass substrates. Interestingly, the retention capacities of LiFePO4 thin films are 76.0% on FTO, 31.2% on ITO, and 37.7% on AZO coated glass substrates at 20th cycle. The initial specific discharge capacity of the LiFePO4/FTO electrode is slightly lower, but the discharge capacities of the LiFePO4/FTO electrode relatively decrease less than those of the others such as LiFePO4/ITO and LiFePO4/AZO with cycling. The results reported here provide the high transparency of LiFePO4 thin films cathode materials and the good candidate as FTO current collector of the LiFePO4 thin film cathode of transparent thin film rechargeable batteries due to its high transparency and cyclic retention.

  9. Mössbauer study of oxide films of Fe-, Sn-, Cr- doped zirconium alloys during corrosion in autoclave

    Energy Technology Data Exchange (ETDEWEB)

    Filippov, V. P., E-mail: vpfilippov@mephi.ru; Bateev, A. B.; Lauer, Yu. A. [National Research Nuclear University “MEPhI” (Moscow Engineering Physics Institute) (Russian Federation)

    2016-12-15

    Mössbauer investigations were used to compare iron atom states in oxide films of binary Zr-Fe, ternary Zr-Fe-Cu and quaternary Zr-Fe-Cr-Sn alloys. Oxide films are received in an autoclave at a temperature of 350–360 °C and at pressure of 16.8 MPa. The corrosion process decomposes the intermetallic precipitates in alloys and forms metallic iron with inclusions of chromium atoms α–Fe(Cr), α–Fe(Cu), α–Fe {sub 2}O{sub 3} and Fe {sub 3}O{sub 4} compounds. Some iron ions are formed in divalent and in trivalent paramagnetic states. The additional doping influences on corrosion kinetics and concentration of iron compounds and phases formed in oxide films. It was shown the correlation between concentration of iron in different chemical states and corrosion resistance of alloys.

  10. Structural, magnetic and transport properties of Co2FeAl Heusler films with varying thickness

    International Nuclear Information System (INIS)

    Wang, Xiaotian; Li, Yueqing; Du, Yin; Dai, Xuefang; Liu, Guodong; Liu, Enke; Liu, Zhongyuan; Wang, Wenhong; Wu, Guangheng

    2014-01-01

    We report on a systematic study of the structural, magnetic properties and the anomalous Hall effect, in the Heusler alloy Co 2 FeAl (CFA) epitaxial films on MgO (001), as a function of film thickness. It was found that the epitaxial CFA films show a highly ordered B2 structure with an in-plane uniaxial magnetic anisotropy. The electrical transport properties reveal that the lattice and magnon scattering contributions to the longitudinal resistivity. Independent on the thickness of films, the anomalous Hall resistivity of CFA films is found to be dominated by skew scattering only. Moreover, the anomalous Hall resistivity shows weakly temperature dependent behavior, and its absolute value increases as the thickness decreases. We attribute this temperature insensitivity in the anomalous Hall resistivity to the weak temperature dependent of tunneling spin-polarization in the CFA films, while the thickness dependence behavior is likely due to the increasing significance of interface or free surface electronic states. - Highlights: ●Highly ordered CFA films with various thicknesses were prepared on MgO substrates. ●The magnon scattering contributions to the longitudinal resistivity in the CFA films. ●The anomalous Hall resistivity of the CFA films shows weakly temperature dependent. ●The CFA films show weak temperature dependent of tunneling spin-polarization

  11. Influence of Fe(Cr) miscibility on thin film grain size and stress

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xuyang; Kaub, Tyler; Martens, Richard L.; Thompson, Gregory B., E-mail: gthompson@eng.ua.edu

    2016-08-01

    During the post coalescence portion of thin film deposition, thin film stress is related to the grain size and adatom mobility of the depositing material. Using a Fe(Cr) alloy thin film, the manipulation of the tensile stress for thick films was studied as a function of Cr solute content up to 8 at.%. Solute concentrations up to 4 at.% resulted in an approximate 50% increase in grain size that resulted in a reduction of the tensile stress to be lower than either elemental film. Upon increasing the Cr content, the grain size refined and the tensile stress of the films increased. Atom probe characterization of the grain boundaries confirmed Cr chemical partitioning which refined the grain size and altered the film's texture, both of which contributed to the change in film stress. The use of intrinsic segregation, rather than deposition processing parameters, appears to be another viable option for regulating film stress. - Highlights: • Solute segregation to regulate grain size in controlling film stress • Quantification of Cr interfacial excess as a function of alloy content • Quantification of texture fiber alignment as a function of Cr content.

  12. Moment mapping of body-centered-cubic Fe{sub x}Mn{sub 1−x} alloy films on MgO(001)

    Energy Technology Data Exchange (ETDEWEB)

    Idzerda, Y. U., E-mail: idzerda@physics.montana.edu; Bhatkar, H. [Department of Physics, Montana State University, Bozeman, Montana 59717 (United States); Arenholz, E. [Advanced Light Source, Lawrence Berkeley National Laboratories, Berkeley, California 59717 (United States)

    2015-05-07

    The alloy composition and elemental magnetic moments of bcc single crystal films of compositionally graded Fe{sub x}Mn{sub 1−x} films (20 nm thick films with 0.8 ≤ x ≤ 0.9) grown on MgO(001) are spatially mapped using X-ray absorption spectroscopy and magnetic circular dichroism. Electron diffraction measurements on single composition samples confirmed that the structure of Fe{sub x}Mn{sub 1−x} films remained epitaxial and in the bcc phase from 0.65 ≤ x ≤ 1, but rotated 45° with respect to the MgO(001) surface net. This is beyond the bulk bcc stability limit of x = 0.88. The Fe moment is found to gradually reduce with increasing Mn content with a very abrupt decline at x = 0.85, a slightly higher composition than observed in the bulk. Surprisingly, the Mn exhibits a very small net moment (<0.1 μ{sub B}) at all compositions, suggesting a complex Mn spin structure.

  13. Isochronal and isothermal crystallization kinetics of amorphous Fe-based alloys

    International Nuclear Information System (INIS)

    Zhang, J.T.; Wang, W.M.; Ma, H.J.; Li, G.H.; Li, R.; Zhang, Z.H.

    2010-01-01

    Using the differential scanning calorimetry (DSC), the isochronal and isothermal crystallization kinetics of amorphous Fe 61 Co 9-x Zr 8 Mo 5 W x B 17 (x = 0 and 2) ribbons was investigated by the Kissinger equation and by the Kolmogorov-Johnson-Mehl-Avrami and Ranganathan-Heimendahl equations, respectively. The results show that tungsten can improve the activation energy E 1 K for the first crystallization in the isochronal annealing process and activation energy E n for the nucleation in the isothermal annealing process, which can be ascribed to the dissolution of tungsten in the amorphous phase. Meanwhile, tungsten can decrease the activation energy E 2 K for the second crystallization in the isochronal annealing process and growth activation energy E g in the isothermal annealing process, which is possibly associated with the formation of W-rich compound after the early nucleation process.

  14. Photoelectrocatalytic activity of liquid phase deposited α-Fe2O3 films under visible light illumination

    International Nuclear Information System (INIS)

    Zhang, Man; Pu, Wenhong; Pan, Shichang; Okoth, Otieno Kevin; Yang, Changzhu; Zhang, Jingdong

    2015-01-01

    Liquid phase deposition (LPD) technique was employed to prepare α-Fe 2 O 3 films for photoelectrocatalytic degradation of pollutants. The obtained LPD films were characterized by various surface analysis techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS). The results indicated that α-Fe 2 O 3 films with porous structure were successfully deposited on the titanium substrates by the LPD process. The UV–Visible diffuse reflectance spectroscopic (DRS) analysis showed that the obtained LPD α-Fe 2 O 3 film mainly absorbed visible light, which was advantageous to the utilization of solar energy. Under visible light illumination, the Fe 2 O 3 film electrodes exhibited sensitive photocurrent responses, which were affected by the calcination temperature. Consistent with the photocurrent analysis, the α-Fe 2 O 3 film calcined at 600 °C showed the best photoelectrocatalytic performance, and different organic pollutants such as methyl orange (MO) and p-nitrophenol (PNP) were effectively degraded over the LPD film electrode by photoelectrocatalytic treatment under visible light illumination. - Highlights: • α-Fe 2 O 3 film is prepared by liquid phase deposition process. • LPD α-Fe 2 O 3 film has a porous structure and absorbs visible light. • Calcination temperature shows a significant effect on the PEC performance of α-Fe 2 O 3 film. • α-Fe 2 O 3 film is efficient for photoelectrocatalytic degradation of pollutants

  15. Effect of starting point formation on the crystallization of amorphous silicon films by flash lamp annealing

    Science.gov (United States)

    Sato, Daiki; Ohdaira, Keisuke

    2018-04-01

    We succeed in the crystallization of hydrogenated amorphous silicon (a-Si:H) films by flash lamp annealing (FLA) at a low fluence by intentionally creating starting points for the trigger of explosive crystallization (EC). We confirm that a partly thick a-Si part can induce the crystallization of a-Si films. A periodic wavy structure is observed on the surface of polycrystalline silicon (poly-Si) on and near the thick parts, which is a clear indication of the emergence of EC. Creating partly thick a-Si parts can thus be effective for the control of the starting point of crystallization by FLA and can realize the crystallization of a-Si with high reproducibility. We also compare the effects of creating thick parts at the center and along the edge of the substrates, and a thick part along the edge of the substrates leads to the initiation of crystallization at a lower fluence.

  16. Giant Faraday Rotation through Ultrasmall Fe0 n Clusters in Superparamagnetic FeO-SiO2 Vitreous Films.

    Science.gov (United States)

    Nakatsuka, Yuko; Pollok, Kilian; Wieduwilt, Torsten; Langenhorst, Falko; Schmidt, Markus A; Fujita, Koji; Murai, Shunsuke; Tanaka, Katsuhisa; Wondraczek, Lothar

    2017-04-01

    Magnetooptical (MO) glasses and, in particular, Faraday rotators are becoming key components in lasers and optical information processing, light switching, coding, filtering, and sensing. The common design of such Faraday rotator materials follows a simple path: high Faraday rotation is achieved by maximizing the concentration of paramagnetic ion species in a given matrix material. However, this approach has reached its limits in terms of MO performance; hence, glass-based materials can presently not be used efficiently in thin film MO applications. Here, a novel strategy which overcomes this limitation is demonstrated. Using vitreous films of x FeO·(100 - x )SiO 2 , unusually large Faraday rotation has been obtained, beating the performance of any other glassy material by up to two orders of magnitude. It is shown that this is due to the incorporation of small, ferromagnetic clusters of atomic iron which are generated in line during laser deposition and rapid condensation of the thin film, generating superparamagnetism. The size of these clusters underbids the present record of metallic Fe incorporation and experimental verification in glass matrices.

  17. Single-Crystal Mesoporous ZnO Thin Films Composed of Nanowalls

    KAUST Repository

    Wang, Xudong; Ding, Yong; Li, Zhou; Song, Jinhui; Wang, Zhong Lin

    2009-01-01

    This paper presents a controlled, large scale fabrication of mesoporous ZnO thin films. The entire ZnO mesoporous film is one piece of a single crystal, while high porosity made of nanowalls is present. The growth mechanism was proposed

  18. Amorphous Silicon-Germanium Films with Embedded Nano crystals for Thermal Detectors with Very High Sensitivity

    International Nuclear Information System (INIS)

    Calleja, C.; Torres, A.; Rosales-Quintero, P.; Moreno, M.

    2016-01-01

    We have optimized the deposition conditions of amorphous silicon-germanium films with embedded nano crystals in a plasma enhanced chemical vapor deposition (PECVD) reactor, working at a standard frequency of 13.56 MHz. The objective was to produce films with very large Temperature Coefficient of Resistance (TCR), which is a signature of the sensitivity in thermal detectors (micro bolometers). Morphological, electrical, and optical characterization were performed in the films, and we found optimal conditions for obtaining films with very high values of thermal coefficient of resistance (TCR = 7.9%K -1 ). Our results show that amorphous silicon-germanium films with embedded nano crystals can be used as thermo sensitive films in high performance infrared focal plane arrays (IRFPAs) used in commercial thermal cameras.

  19. Crystal orientation dependent thermoelectric properties of highly oriented aluminum-doped zinc oxide thin films

    KAUST Repository

    Abutaha, Anas I.

    2013-02-06

    We demonstrate that the thermoelectric properties of highly oriented Al-doped zinc oxide (AZO) thin films can be improved by controlling their crystal orientation. The crystal orientation of the AZO films was changed by changing the temperature of the laser deposition process on LaAlO3 (100) substrates. The change in surface termination of the LaAlO3 substrate with temperature induces a change in AZO film orientation. The anisotropic nature of electrical conductivity and Seebeck coefficient of the AZO films showed a favored thermoelectric performance in c-axis oriented films. These films gave the highest power factor of 0.26 W m−1 K−1 at 740 K.

  20. Microstructure and mechanical properties of ion-beam-produced Fe-Ti-(N), Fe-Ti-(C), and Fe-Ti-(C,N) surface films

    Science.gov (United States)

    Hirvonen, J.-P.; Nastasi, M.; Zocco, T. G.; Jervis, T. R.

    1990-06-01

    Ion-mixed films of Fe53 Ti47 were produced by ion irradiating a Fe-Ti multilayer structure on AISI 304 stainless steel. The ion-mixed films were subsequently implanted with nitrogen, carbon, or both carbon and nitrogen. The microstructure following nitrogen implantation consisted of a bcc solid solution of iron and titanium and finely dispersed TiN precipitates. In the cases of carbon or carbon and nitrogen implantation, a two-phase structure consisting of an amorphous matrix with TiC or Ti(C,N) precipitates was found. All these films initially possessed improved tribological properties as revealed by lowered friction and increased wear resistance. However, after an extended test of 1000 wear cycles, a reduced friction was only observed for the carbon or carbon and nitrogen implanted samples. The wear track on the dual implanted surface was extremely smooth, while the surface of the nitrogen-implanted sample was partly worn through, causing the friction to increase to the level of the untreated sample. The improved tribological properties of the implanted films are attributed to an increase in surface hardness. However, the surface hardness is unable to explain differences between different implantations. In the case of the dual carbon and nitrogen implantation, improvements appear to be in part the result from an increased capability to accommodate plastic deformation. These conclusions are supported by transmission electron microscope studies of the wear tracks as well as by nanoindentation measurements.

  1. First-order phase transitions in CaFe2As2 single crystal: a local probe study

    International Nuclear Information System (INIS)

    Alzamora, M; Munevar, J; Baggio-Saitovitch, E; Bud'ko, S L; Ni Ni; Canfield, P C; Sanchez, D R

    2011-01-01

    57 Fe Moessbauer spectroscopy has been used to investigate the structural and magnetic phase transitions of CaFe 2 As 2 (T N = 173 K) single crystals. For this compound we found that V ZZ is positive and parallel to the c-axis of the tetragonal structure. For CaFe 2 As 2 a magnetic hyperfine field B hf was observed at the 57 Fe nucleus below T N ∼ 173 K. Analysis of the temperature dependence of B hf data using the Bean-Rodbell model shows that the Fe spins undergo a first-order magnetic transition at ∼ 173 K. A collinear antiferromagnetic structure is established below this temperature with the Fe spin lying in the (a, b) plane. Below T N the paramagnetic fraction of Fe decreases down to 150 K and for lower temperatures all the Fe spins are magnetically ordered.

  2. Epitaxial growth and magnetic properties of Fe4-xMnxN thin films grown on MgO(0 0 1) substrates by molecular beam epitaxy

    Science.gov (United States)

    Anzai, Akihito; Takata, Fumiya; Gushi, Toshiki; Toko, Kaoru; Suemasu, Takashi

    2018-05-01

    Epitaxial Fe4-xMnxN (x = 0, 1, 2, 3, and 4) thin films were successfully grown on MgO(0 0 1) single-crystal substrates by molecular beam epitaxy, and their crystalline qualities and magnetic properties were investigated. It was found that the lattice constants of Fe4-xMnxN obtained from X-ray diffraction measurement increased with the Mn content. The ratio of the perpendicular lattice constant c to the in-plane lattice constant a of Fe4-xMnxN was found to be about 0.99 at x ⩾ 2. The magnetic properties evaluated using a vibrating sample magnetometer at room temperature revealed that all of the Fe4-xMnxN films exhibited ferromagnetic behavior regardless of the value of x. In addition, the saturation magnetization decreased non-linearly as the Mn content increased. Finally, FeMn3N and Mn4N exhibited perpendicular anisotropy and their uniaxial magnetic anisotropy energies were 2.2 × 105 and 7.5 × 105 erg/cm3, respectively.

  3. Mössbauer spectroscopy study of 60P2O5-40Fe2O3 glass crystallization

    Directory of Open Access Journals (Sweden)

    Stoch Paweł

    2015-03-01

    Full Text Available 60P2O5-40Fe2O3 glass was synthesized and 57Fe Mössbauer spectroscopy study was presented. The main goal of the research was to investigate structural changes of local environment of iron ions during gradual crystallization of the glass. It was observed that some changes were evidenced at temperature of heat treatment higher than 400°C, above which content of tetrahedrally coordinated Fe3+ was increased in cost of octahedral sites. This led to formation of areas of nucleation of α-FePO4. Crystallization of α-Fe3(P2O72 and Fe2P2O7 was also observed.

  4. Tip-Dependent Scanning Tunneling Microscopy Imaging of Ultrathin FeO Films on Pt(111)

    DEFF Research Database (Denmark)

    Merte, Lindsay Richard; Grabow, Lars C.; Peng, Guowen

    2011-01-01

    High-resolution scanning tunneling microscope (STM) images of moiré-structured FeO films on Pt(111) were obtained in a number of different tip-dependent imaging modes. For the first time, the STM images are distinguished and interpreted unambiguously with the help of distinct oxygen...

  5. Evolution of free volume in ultrasoft magnetic FeZrN films during thermal annealing

    NARCIS (Netherlands)

    Chechenin, NG; van Veen, A; Schut, H; Chezan, AR; Boerma, DO; Vystavel, T; De Hosson, JTM; DeHaven, PW; Field, DP; Harkness, SD; Sutliff, JA; Szpunar, JA; Tang, L; Thomson, T; Vaudin, MD

    2002-01-01

    The thermal stability of nanocrystalline ultra-soft magnetic (Fe98Zr2)(1-x)N-x films with x=0.10-0.25 was studied using high-resolution transmission electron microscopy (HRTEM), positron beam analysis (PBA) and thermal desorption spectrometry (TDS). The results demonstrate that grain growth during

  6. On the frequency dependence of the magnetic permeability of FeHfO thin films

    NARCIS (Netherlands)

    Bloemen, P.J.H.; Rulkens, B.

    1998-01-01

    The frequency dependence of the magnetic permeability as well as of the electrical impedance have been investigated for soft-magnetic granular FeHfO thin films. The impedance measurements indicate that capacitive effects resulting from the inhomogeneous structure of the layers are of no importance

  7. On the GHz frequency response in nanocrystalline FeXN ultra-soft magnetic films

    NARCIS (Netherlands)

    Chechenin, NG; Craus, CB; Chezan, AR; Vystavel, T; Boerma, DO; De Hosson, JTM; Niesen, L; Tidrow, SC; Horwitz, JS; Xi, XX; Levy, J

    2002-01-01

    The periodicity and angular spread of the in-plane magnetization for ultrasoft nanocrystalline FeZrN films were estimated from an analysis of the ripple structure, observed in Lorentz transmission electron microscopy (LTEM) images. The influence of the micromagnetic ripple on the ferromagnetic

  8. Formation dynamics of FeN thin films on Cu(100)

    KAUST Repository

    Heryadi, Dodi; Schwingenschlö gl, Udo

    2012-01-01

    To investigate the structural and magnetic properties of thin films of FeN we have performed ab initio molecular dynamics simulations of their formation on Cu(100) substrates. The iron nitride layers exhibit a p4gm(2 × 2) reconstruction and order

  9. Magnetic properties of FeNi-based thin film materials with different additives

    KAUST Repository

    Liang, C.; Gooneratne, C.P.; Wang, Q.X.; Liu, Y.; Gianchandani, Y.; Kosel, Jü rgen

    2014-01-01

    This paper presents a study of FeNi-based thin film materials deposited with Mo, Al and B using a co-sputtering process. The existence of soft magnetic properties in combination with strong magneto-mechanical coupling makes these materials

  10. Scaling of anomalous hall effect in amorphous CoFeB Films with accompanying quantum correction

    KAUST Repository

    Zhang, Yan; Mi, Wenbo; Wang, Xiaocha; Guo, Zaibing

    2015-01-01

    Scaling of anomalous Hall effect in amorphous CoFeB films with thickness ranging from 2 to 160 nm have been investigated. We have found that the scaling relationship between longitudinal (ρxx) and anomalous Hall (ρAH) resistivity is distinctly

  11. A study on electrodeposited NixFe1−x alloy films

    Indian Academy of Sciences (India)

    on the magnetic and magnetoresistance properties of NiFe alloy films are mostly focused on the ... is clear from the figure that the Ni deposit content is measured to be 42 wt% for .... grain size change, the degree of ferromagnetic coupling etc.

  12. Scaling of Anomalous Hall Effects in Facing-Target Reactively Sputtered Fe4N Films

    KAUST Repository

    Zhang, Yan; Mi, Wenbo; Wang, Xiaocha; Zhang, Xixiang

    2015-01-01

    boundaries scattering have a major impact on the AHE scaling law. The scaling exponent γ in the conventional scaling of is larger than 2 in both the epitaxial and polycrystalline γ′-Fe4N films. Although γ>2 has been found in heterogeneous systems due

  13. Enhanced photoresponse of FeS2 films: the role of Marcasite-Pyrite phase junctions

    NARCIS (Netherlands)

    Wu, L.; Dzade, N.Y.; Gao, L.; Scanlon, D.O.; Öztürk, Z.; Hollingsworth, N.; Weckhuysen, B.M.; Hensen, E.J.M.; De Leeuw, N.H.; Hofmann, J.P.

    2016-01-01

    The beneficial role of marcasite in iron-sulfide-based photo-electrochemical applications is reported for the first time. A spectacular improvement of the photoresponse observed experimentally for mixed pyrite/marcasite-FeS2 films can be ascribed to the presence of p/m phase junctions at the

  14. Enhanced Photoresponse of FeS2 Films : The Role of Marcasite–Pyrite Phase Junctions

    NARCIS (Netherlands)

    Wu, Longfei; Dzade, N.Y.; Gao, L.; Scanlon, D. O.; Özturk, Zafer; Hollingsworth, N.; Weckhuysen, B.M.; Hensen, E. J. M.; de Leeuw, Nora H.; Hofmann, J. P.

    2016-01-01

    The beneficial role of marcasite in iron sulfide-based photo-electrochemical applications is reported for the first time. A spectacular improvement of the photoresponse observed experimentally for mixed pyrite/marcasite-FeS2 films can be ascribed to the presence of p/m phase junctions at the

  15. The role of the interface on the magnetic behaviour of granular Fe50Ag50 film

    International Nuclear Information System (INIS)

    Fdez-Gubieda, M.L.; Sarmiento, G.; Fernandez Barquin, L.; Orue, I.

    2007-01-01

    The magnetic behaviour of a Fe 50 Ag 50 granular thin film has been studied by means of AC and DC magnetic measurements. Exchange coupling between magnetic nanoparticles appears at T=<200K decreasing the coercive field of the sample. Additionally, an exchange bias is observed at low temperature related to the existence of a spin disordered interface around the nanoparticles

  16. Depth resolved lattice-charge coupling in epitaxial BiFeO3 thin film

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyeon Jun; Lee, Sung Su; Kwak, Jeong Hun; Kim, Young-Min; Jeong, Hu Young; Borisevich, Albina Y.; Lee, Su Yong; Noh, Do Young; Kwon, Owoong; Kim, Yunseok; Jo, Ji Young

    2016-12-01

    For epitaxial films, a critical thickness (tc) can create a phenomenological interface between a strained bottom layer and a relaxed top layer. Here, we present an experimental report of how the tc in BiFeO3 thin films acts as a boundary to determine the crystalline phase, ferroelectricity, and piezoelectricity in 60 nm thick BiFeO3/SrRuO3/SrTiO3 substrate. We found larger Fe cation displacement of the relaxed layer than that of strained layer. In the time-resolved X-ray microdiffraction analyses, the piezoelectric response of the BiFeO3 film was resolved into a strained layer with an extremely low piezoelectric coefficient of 2.4 pm/V and a relaxed layer with a piezoelectric coefficient of 32 pm/V. The difference in the Fe displacements between the strained and relaxed layers is in good agreement with the differences in the piezoelectric coefficient due to the electromechanical coupling.

  17. Structural, mechanical, and magnetic properties of GaFe{sub 3}N thin films

    Energy Technology Data Exchange (ETDEWEB)

    Junaid, Muhammad, E-mail: junaid@mch.rwth-aachen.de; Music, Denis, E-mail: music@mch.rwth-aachen.de; Hans, Marcus; Schneider, Jochen M. [Materials Chemistry, RWTH Aachen University, D-52056 Aachen (Germany); Scholz, Tanja; Dronskowski, Richard [Institute of Inorganic Chemistry, RWTH Aachen University, D-52056 Aachen (Germany); Primetzhofer, Daniel [Department of Physics and Astronomy, Uppsala University, Lägerhyddsvägen 1, S-75120 Uppsala (Sweden)

    2016-07-15

    Using the density-functional theory, the structural, mechanical, and magnetic properties were investigated for different GaFe{sub 3}N configurations: ferromagnetic, ferrimagnetic, paramagnetic, and nonmagnetic. Ferrimagnetic and high-spin ferromagnetic states exhibit the lowest energy and are the competing ground states as the total energy difference is 0.3 meV/atom only. All theoretically predicted values could be fully confirmed by experiments. For this, the authors synthesized phase pure, homogeneous, and continuous GaFe{sub 3}N films by combinatorial reactive direct current magnetron sputtering. Despite the low melting point of gallium, the authors succeeded in the growth of GaFe{sub 3}N films at a temperature of 500 °C. Those thin films exhibit a lattice parameter of 3.794 Å and an elastic modulus of 226 ± 20 GPa. Magnetic susceptibility measurements evidence a magnetic phase transitions at 8.0 ± 0.1 K. The nearly saturated magnetic moment at ±5 T is about 1.6 μB/Fe and is close to the theoretically determined magnetic moment for a ferrimagnetic ordering (1.72 μB/Fe).

  18. Structural, mechanical, and magnetic properties of GaFe_3N thin films

    International Nuclear Information System (INIS)

    Junaid, Muhammad; Music, Denis; Hans, Marcus; Schneider, Jochen M.; Scholz, Tanja; Dronskowski, Richard; Primetzhofer, Daniel

    2016-01-01

    Using the density-functional theory, the structural, mechanical, and magnetic properties were investigated for different GaFe_3N configurations: ferromagnetic, ferrimagnetic, paramagnetic, and nonmagnetic. Ferrimagnetic and high-spin ferromagnetic states exhibit the lowest energy and are the competing ground states as the total energy difference is 0.3 meV/atom only. All theoretically predicted values could be fully confirmed by experiments. For this, the authors synthesized phase pure, homogeneous, and continuous GaFe_3N films by combinatorial reactive direct current magnetron sputtering. Despite the low melting point of gallium, the authors succeeded in the growth of GaFe_3N films at a temperature of 500 °C. Those thin films exhibit a lattice parameter of 3.794 Å and an elastic modulus of 226 ± 20 GPa. Magnetic susceptibility measurements evidence a magnetic phase transitions at 8.0 ± 0.1 K. The nearly saturated magnetic moment at ±5 T is about 1.6 μB/Fe and is close to the theoretically determined magnetic moment for a ferrimagnetic ordering (1.72 μB/Fe).

  19. Gilbert damping constant of FePd alloy thin films estimated by broadband ferromagnetic resonance

    Directory of Open Access Journals (Sweden)

    Kawai T.

    2014-07-01

    Full Text Available Magnetic relaxation of FePd alloy epitaxial thin films with very flat surfaces prepared on MgO(001 substrate are measured by in-plane broadband ferromagnetic resonance (FMR. Magnetic relaxation is investigated as Δω for FMR absorption peak by frequency sweep measurements. ΔH is calculated by using the measured Δω. Gilbert damping constant, α, is estimated by employing a straight line fitting of the resonant frequency dependence of ΔH. The α value for an FePd film deposited at 200 ˚C, which shows disordered A1 structure, is 0.010 and ΔH0, which is frequency independent part of ΔH, is 10 Oe. The α value for a film annealed at 400 ˚C, which shows partially L10 ordered structure (S=0.32, is 0.013, which is slightly larger than that for the disorder A1 structure film. However, ΔH0 for the annealed film is 85 Oe, which is much larger than that for the film with disordered structure. The results show that the magnetic relaxation of the 400 ˚C annealed film is mainly dominated by ΔH0, which is related with magnetic in-homogeneity caused by the appearance of perpendicular anisotropy of partially ordered phase.

  20. Effect of tungsten (W) on structural and magnetic properties of electroplated NiFe thin films for MEMS applications

    Science.gov (United States)

    Kannan, R.; Devaki, P.; Premkumar, P. S.; Selvambikai, M.

    2018-04-01

    Electrodeposition of nanocrystalline NiFe and NiFeW thin films were carried out from ammonium citrate bath at a constant current density and controlled pH of 8 by varying the bath temperature from 40 °C to 70 °C. The surface morphology and chemical composition of the electrodeposited NiFe and NiFeW soft magnetic thin films were studied by using SEM and EDAX. The SEM micrographs of the films coated at higher electrodeposited bath temperature have no micro cracks and also the films have more uniform surface morphology. The existence of crystalline nature of the coated films were analysed by XRD. The presence of predominant peaks in x-ray diffraction pattern (compared with JCPDS data) reveal that the average crystalline size was in the order of few tens of nano meters. The magnetic properties such as coercivity, saturation magnetization and magnetic flux density have been calculated from vibrating sample magnetometer analysis. The VSM result shows that the NiFeW thin film synthesised at 70 °C exhibit the lower coercivity with higher saturation magnetization. The hardness and adhesion of the electroplated films have been investigated. Reasons for variation in magnetic properties and structural characteristics are also discussed. The electroplated NiFe and NiFeW thin films can be used for Micro Electro Mechanical System (MEMS) applications due to their excellent soft magnetic behaviour.

  1. Temperature dependent magnetic coupling between ferromagnetic FeTaC layers in multilayer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Akhilesh Kumar [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Hsu, Jen-Hwa [Department of Physics, National Taiwan University, Taipei 10617, Taiwan (China); Perumal, Alagarsamy, E-mail: perumal@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India)

    2016-11-15

    We report systematic investigations on temperature dependent magnetic coupling between ferromagnetic FeTaC layers and resulting magnetic properties of multilayer structured [FeTaC (~67 nm)/Ta(x nm)]{sub 2}/FeTaC(~67 nm)] thin films, which are fabricated directly on thermally oxidized Si substrate. As-deposited amorphous films are post annealed at different annealing temperatures (T{sub A}=200, 300 and 400 °C). Structural analyzes reveal that the films annealed at T{sub A}≤200 °C exhibit amorphous nature, while the films annealed above 200 °C show nucleation of nanocrystals at T{sub A}=300 °C and well-defined α-Fe nanocrystals with size of about 9 nm in amorphous matrix for 400 °C annealed films. Room temperature and temperature dependent magnetic hysteresis (M–H) loops reveal that magnetization reversal behaviors and magnetic properties are strongly depending on spacer layer thickness (x), T{sub A} and temperature. A large reduction in coercivity (H{sub C}) was observed for the films annealed at 200 °C and correlated to relaxation of stress quenched in during the film deposition. On the other hand, the films annealed at 300 °C exhibit unusual variation of H{sub C}(T), i.e., a broad minimum in H{sub C}(T) vs T curve. This is caused by change in magnetic coupling between ferromagnetic layers having different microstructure. In addition, the broad minimum in the H{sub C}(T) curve shifts from 150 K for x=1 film to 80 K for x=4 film. High-temperature thermomagnetization data show a strong (significant) variation of Curie temperature (T{sub C}) with T{sub A} (x). The multilayer films annealed at 200 °C exhibit low value of T{sub C} with a minimum of 350 K for x=4 film. But, the films annealed at 400 °C show largest T{sub C} with a maximum of 869 K for x=1 film. The observed results are discussed on the basis of variations in magnetic couplings between FeTaC layers, which are majorly driven by temperature, spacer layer thickness, annealing temperature and

  2. Stress and stability of sputter deposited A-15 and bcc crystal structure tungsten thin films

    Energy Technology Data Exchange (ETDEWEB)

    O' Keefe, M.J.; Stutz, C.E.

    1997-07-01

    Magnetron sputter deposition was used to fabricate body centered cubic (bcc) and A-15 crystal structure W thin films. Previous work demonstrated that the as-deposited crystal structure of the films was dependent on the deposition parameters and that the formation of a metastable A-15 structure was favored over the thermodynamically stable bcc phase when the films contained a few atomic percent oxygen. However, the A-15 phase was shown to irreversibly transform into the bcc phase between 500 C and 650 C and that a significant decrease in the resistivity of the metallic films was measured after the transformation. The current investigation of 150 nm thick, sputter deposited A-15 and bcc tungsten thin films on silicon wafers consisted of a series of experiments in which the stress, resistivity and crystal structure of the films was measured as a function of temperatures cycles in a Flexus 2900 thin film stress measurement system. The as-deposited film stress was found to be a function of the sputtering pressure and presputter time; under conditions in which the as-deposited stress of the film was {approximately}1.5 GPa compressive delamination of the W film from the substrate was observed. Data from the thermal studies indicated that bcc film stress was not affected by annealing but transformation of the A-15 structure resulted in a large tensile increase in the stress of the film, regardless of the as-deposited stress of the film. In several instances, complete transformation of the A-15 structure into the bcc phase resulted in {ge}1 GPa tensile increase in film stress.

  3. Stress and stability of sputter deposited A-15 and bcc crystal structure tungsten thin films

    International Nuclear Information System (INIS)

    O'Keefe, M.J.; Stutz, C.E.

    1997-01-01

    Magnetron sputter deposition was used to fabricate body centered cubic (bcc) and A-15 crystal structure W thin films. Previous work demonstrated that the as-deposited crystal structure of the films was dependent on the deposition parameters and that the formation of a metastable A-15 structure was favored over the thermodynamically stable bcc phase when the films contained a few atomic percent oxygen. However, the A-15 phase was shown to irreversibly transform into the bcc phase between 500 C and 650 C and that a significant decrease in the resistivity of the metallic films was measured after the transformation. The current investigation of 150 nm thick, sputter deposited A-15 and bcc tungsten thin films on silicon wafers consisted of a series of experiments in which the stress, resistivity and crystal structure of the films was measured as a function of temperatures cycles in a Flexus 2900 thin film stress measurement system. The as-deposited film stress was found to be a function of the sputtering pressure and presputter time; under conditions in which the as-deposited stress of the film was approximately1.5 GPa compressive delamination of the W film from the substrate was observed. Data from the thermal studies indicated that bcc film stress was not affected by annealing but transformation of the A-15 structure resulted in a large tensile increase in the stress of the film, regardless of the as-deposited stress of the film. In several instances, complete transformation of the A-15 structure into the bcc phase resulted in ge1 GPa tensile increase in film stress

  4. Research by Moessbauer and infrared spectroscopy of films of polyacrylonitrile doped with FeCl2 and FeCl3

    International Nuclear Information System (INIS)

    Santos, Vadilson M. dos; Silva Filho, Eloi A. da; Nunes Filho, Evaristo

    2009-01-01

    The heating effect on films of polyacrylonitrile and doping of the ions Fe(II) and Fe (III) may reveal important aspects of the use of this polymer in the search for new materials. This paper was done the doping of the films of PAN with ions Fe(II) and Fe (III), with thermo heating is range of 60 a 90 deg C e de 90 a 170 deg C through the alkaline and acid hydrolysis of the CN groups used spectroscopy of FTIR and Moessbauer techniques to evaluate the structural changes results of doping process this polymer. The results showed that the FTIR spectral have a strong interaction of the ions Fe(II) and Fe (III) with PAN and confirmed by Moessbauer data. (author)

  5. Ferromagnetic resonance spectroscopy of CoFeZr-Al{sub 2}O{sub 3} granular films containing “FeCo core – oxide shell” nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kołtunowicz, Tomasz N., E-mail: t.koltunowicz@pollub.pl [Department of Electrical Devices and High Voltage Technology, Lublin University of Technology, Nadbystrzycka 38a, 20-618 Lublin (Poland); Zukowski, Pawel [Department of Electrical Devices and High Voltage Technology, Lublin University of Technology, Nadbystrzycka 38a, 20-618 Lublin (Poland); Sidorenko, Julia [Department of Semiconductors Physics and Nanoelectronics, Belarusian State University, Independence Av. 4, 220030 Minsk (Belarus); Bayev, Vadim; Fedotova, Julia A. [Institute for Nuclear Problems, Belarusian State University, Bobrujskaya Str. 11, 220030 Minsk (Belarus); Opielak, Marek [Institute of Transport, Combustion Engines and Ecology, Lublin University of Technology, Nadbystrzycka 36, 20-618 Lublin (Poland); Marczuk, Andrzej [Department of Transporting and Agricultural Machinery, University of Life Sciences in Lublin, Głeboka 28, 20-612 Lublin (Poland)

    2017-01-01

    Ferromagnetic resonance (FMR) spectroscopy is applied for comparative analysis of granular (CoFeZ){sub x}(Al{sub 2}O{sub 3}){sub 100−x}, (31 at%≤x≤47 at%) films containing pure FeCo-based nanoparticles (NPs) or “FeCo-based core – oxide shell” NPs inside Al{sub 2}O{sub 3} matrix when deposited in oxygen-free or oxygen-containing atmosphere, correspondingly. It is established that g-factor extracted from the FMR spectra of films with core–shell NPs decreases with x below the value g =2.0023 for free electron that is untypical for metallic NPs. This effect is associated with the formation of the interface between ferromagnetic core and antiferromagnetic (ferrimagnetic) oxide shell of NPs. - Highlights: • CoFeZr-Al{sub 2}O{sub 3} granular films containing “FeCo core – oxide shell” nanoparticles. • magnetic anisotropy of (CoFeZr){sub x}(Al{sub 2}O{sub 3}){sub 100−x} films is of an easy plane type. • essential difference in dependence of g-factor on metal content in non- and oxidized film. • non-oxidized samples indicates the reduction of the value of films magnetization.

  6. Study of electronic structure and magnetic properties of epitaxial Co{sub 2}FeAl Heusler Alloy Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Soni, S. [Department of Pure & Applied Physics, University of Kota, Kota 324007 (India); Dalela, S., E-mail: sdphysics@rediffmail.com [Department of Pure & Applied Physics, University of Kota, Kota 324007 (India); Sharma, S.S. [Department of Physics, Govt. Women Engineering College, Ajmer (India); Liu, E.K.; Wang, W.H.; Wu, G.H. [State Key Laboratory for Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Kumar, M. [Department of Physics, Malviya National Institute of Technology, Jaipur-302017 (India); Garg, K.B. [Department of Physics, University of Rajasthan, Jaipur-302004 (India)

    2016-07-25

    This work reports the magnetic and electronic characterization of plane magnetized buried Heusler Co{sub 2}FeAl nano thin films of different thickness by X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) measurements. . The spectra on both Fe- and Co L{sub 2,3} edges show a pronounced magnetic dichroic signal in remanence, corresponding to a ferromagnetically-aligned moments on Fe and Co atoms conditioning the peculiar characteristics of the Co{sub 2}FeAl Heusler compound (a half-metallic ferromagnet). The detailed knowledge of the related magnetic and electronic properties of these samples over a wide range of thickness of films are indispensable for achieving a higher tunnel magnetoresistance ratio, and thus for spintronics device applications. - Highlights: • Electronic structure and Magnetic Properties of Epitaxial Co{sub 2}FeAl Heusler Films. • X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD). • Fe- and Co L{sub 2,3} edges show a pronounced magnetic dichroic signal in remanence. • Calculated Orbital, Spin and total magnetic moments of Fe and Co for 30 nm Co{sub 2}FeAl thin film. • The total magnetic moment of Fe at L{sub 2,3} edges increases with the thickness of the Co2FeAl films.

  7. Interface thermal resistance of nanostructured FeCoCu film and Si substrate

    Science.gov (United States)

    Nikolaenko, Yuri M.; Medvedev, Yuri V.; Genenko, Yuri A.; Ghafari, Mohammad; Hahn, Horst

    2006-05-01

    Results of measurement of thermal resistance (RFS ) of film substrate interface of 10 nm (Fe1-x Cox )1-y Cuy film on Si substrate with 50 nm SiO2 sublayer are presented. The estimated magnitude is two orders greater then RFS of epitaxial manganite films on StTiO3 substrate with and without sublayer. The significant increase of RFS is explained by granular structure of film with average size of grain about 10 nm. In this case the additional thermal barier in the film-substrate interface is appeared. It provides the change of regime of phonons propagation from ballistic to diffusion one. The principle possibility of variation of RFS in wide range as a task of nanotechnology is discussed.

  8. Crystal structure and magnetic properties of a nitrogenated melt-spun Sm[sub 2]Fe[sub 17] compound

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Choong-Jin [Electromagnetic Materials Laboratory, Research Institute of Industrial Science and Technology, P.O. Box 135, 790-330 Pohang (Korea, Republic of); Lee, Woo-Young [Electromagnetic Materials Laboratory, Research Institute of Industrial Science and Technology, P.O. Box 135, 790-330 Pohang (Korea, Republic of); Choi, Seung-Duck [Electromagnetic Materials Laboratory, Research Institute of Industrial Science and Technology, P.O. Box 135, 790-330 Pohang (Korea, Republic of)

    1994-05-15

    Sm[sub 2]Fe[sub 17]N[sub 2.9] compound powders were prepared from parent alloys of Sm[sub 2]Fe[sub 17] which were made by both arc melting and rapid solidification processes. The cast Sm[sub 2]Fe[sub 17] contained mixed phases of SmFe[sub 3] and [alpha]-Fe, and correspondingly formed less Sm[sub 2]Fe[sub 17]N[sub x] with a rather large amount of residual [alpha]-Fe after nitrogenation. The melt-spun Sm[sub 2]Fe[sub 17] compound, however, was single phase and exhibited a negligible amount of residual [alpha]+Fe after nitrogenation. The residual amount of free iron was found to increase as a function of milling time and to impede the development of promising permanent magnetic properties. The melt-spun Sm[sub 2]Fe[sub 17]N[sub x] compound powders exhibited a coercivity value [sub i]H[sub c] of 5 kOe, which is double that of the as-cast Sm[sub 2]Fe[sub 17]N[sub x] powders and a high remanence B[sub r]=60 e.m.u. g[sup -1]. The average magnetic moment of Fe atoms in the crystal is estimated to be 2.29 [mu][sub B] and the Fe atom in the 6c site exhibits the highest magnetic moment of 2.65 [mu][sub B]. The expansion in the c axial direction of the nitrogenated crystal was found to be mainly due to extension of Sm(6c)-Fe(c) and Fe(18f)-Fe(18f) distances. ((orig.))

  9. Novel Chiral Magnetic Domain Wall Structure in Fe/Ni/Cu(001) Films

    Science.gov (United States)

    Chen, G.; Zhu, J.; Quesada, A.; Li, J.; N'Diaye, A. T.; Huo, Y.; Ma, T. P.; Chen, Y.; Kwon, H. Y.; Won, C.; Qiu, Z. Q.; Schmid, A. K.; Wu, Y. Z.

    2013-04-01

    Using spin-polarized low energy electron microscopy, we discovered a new type of domain wall structure in perpendicularly magnetized Fe/Ni bilayers grown epitaxially on Cu(100). Specifically, we observed unexpected Néel-type walls with fixed chirality in the magnetic stripe phase. Furthermore, we find that the chirality of the domain walls is determined by the film growth order with the chirality being right handed in Fe/Ni bilayers and left handed in Ni/Fe bilayers, suggesting that the underlying mechanism is the Dzyaloshinskii-Moriya interaction at the film interfaces. Our observations may open a new route to control chiral spin structures using interfacial engineering in transition metal heterostructures.

  10. Magnetic domain observation of FeCo thin films fabricated by alternate monoatomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ohtsuki, T., E-mail: ohtsuki@spring8.or.jp; Kotsugi, M.; Ohkochi, T. [Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Kojima, T.; Mizuguchi, M.; Takanashi, K. [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2014-01-28

    FeCo thin films are fabricated by alternate monoatomic layer deposition method on a Cu{sub 3}Au buffer layer, which in-plane lattice constant is very close to the predicted value to obtain a large magnetic anisotropy constant. The variation of the in-plane lattice constant during the deposition process is investigated by reflection high-energy electron diffraction. The magnetic domain images are also observed by a photoelectron emission microscope in order to microscopically understand the magnetic structure. As a result, element-specific magnetic domain images show that Fe and Co magnetic moments align parallel. A series of images obtained with various azimuth reveal that the FeCo thin films show fourfold in-plane magnetic anisotropy along 〈110〉 direction, and that the magnetic domain structure is composed only of 90∘ wall.

  11. Multiple oxide content media for columnar grain growth in L10 FePt thin films

    International Nuclear Information System (INIS)

    Ho, Hoan; Yang, En; Laughlin, David E.; Zhu, Jian-Gang

    2013-01-01

    An approach to enhance the height-to-diameter ratio of FePt grains in heat-assisted magnetic recording media is proposed. The FePt-SiO x thin films are deposited with a decrease of the SiO x percentage along the film growth direction. When bi-layer and tri-layer media are sputt