Journal of the Magnetics Society of Japan
Online ISSN : 1882-2932
Print ISSN : 1882-2924
ISSN-L : 1882-2924
38 巻, 2-2 号
選択された号の論文の7件中1~7を表示しています
  • Y. Sakuraba , M. Ueda , S. Bosu , K. Saito , K. Takanashi
    2014 年 38 巻 2-2 号 p. 45-49
    発行日: 2014/03/01
    公開日: 2014/03/20
    ジャーナル オープンアクセス
      Co2FexMn1-xSi (CFMS) is one of the most attractive highly spin-polarized materials since large tunnel magneto-resistance and giant magneto-resistance have been recenltly observed in the devices using CFMS electrodes. In this study, we investigated the dependence of CPP-GMR in CFMS/Ag/CFMS on Fe composition x and annealing temperature Tann for CFMS electrodes. The highest intrinsic MR ratio of 55% and ΔRA of 17.2 mΩ•μm2 were achieved at x = 0.5 and Tann = 550°C. Finally, we compared the results on CPP-GMR with those on TMR, anisotropic magneto-resistance and damping constant for CFMS and discussed half-metallicity of CFMS.
  • P.J. Hasnip, C.H. Loach, J.H. Smith, M.I.J. Probert, D. Gilks, J. Size ...
    2014 年 38 巻 2-2 号 p. 50-55
    発行日: 2014/03/01
    公開日: 2014/03/20
    ジャーナル オープンアクセス
      Co-based full Heusler alloys have attracted significant attention due to their high spin polarisation and successful integration as electrodes in magnetic tunnelling junctions and current-perpendicular-to-plane spin valves (CPP-SV)._Further improvement of the CFMS based CPP-SVs requires a fundamental understanding of the effects of atomic disorder within the Heusler alloys. In this work we present a theoretical study of disorder in CFMS alloys using ab initio simulations, guided by images from Z-contrast scanning-TEM of sample films. The simulations are based on density functional theory plus a Hubbard U term, allowing the investigation of the effects of atomic disorder on the spin-polarisation at the Fermi level, and computation of the disorder formation energy. It is found that in order to retain the high spin-polarisation at the Fermi level the integrity of the Co-sublattice should be preserved, but that the effect of mixing between the Fe/Mn and Si sublattices (B2 phase) varies dramatically depending on the precise nature of the disorder and the chemical composition of the CFMS. Calculations of the spin-polarisation at the Fermi energy show that Co2Fe0.5Mn0.5Si is especially robust with respect to such intermixing, an observation which may explain the good performance of films in this composition range.
  • H. Sato, M. Yamanouchi, S. Ikeda, S. Fukami, F. Matsukura, H. Ohno
    2014 年 38 巻 2-2 号 p. 56-60
    発行日: 2014/03/01
    公開日: 2014/03/20
    ジャーナル オープンアクセス
      CoFeB-MgO based magnetic tunnel junctions with perpendicular easy axis are attracting much interest for application to nonvolatile very large scale integrated circuits. MgO/CoFeB/Ta/CoFeB/MgO recording structure with double-interface shows a high thermal stability factor without an increase of intrinsic critical current with comparison to MgO/CoFeB recording structure with single-interface. In this paper, we review our recent progress on the CoFeB-MgO magnetic tunnel junctions with a double MgO barrier (MgO/CoFeB/Ta/CoFeB/MgO) recording structure. It enabled us to obtain magnetic tunnel junctions with a high thermal stability factor of 59 at a device dimension of 29 nm in diameter.
  • R. Carpenter, N. C. Cramp, G. Vallejo-Fernandez, K. O’Grady
    2014 年 38 巻 2-2 号 p. 61-65
    発行日: 2014/03/01
    公開日: 2014/03/20
    [早期公開] 公開日: 2014/02/19
    ジャーナル オープンアクセス
    In this paper the current state of knowledge of the magnetic structure interfaces in exchange biased systems are briefly reviewed. A conceptual model explaining the interface in terms of spin clusters that behave in a similar manner to fine particles displaying superparamagnetism is described. To test this concept IrMn/CoFe based exchange biased polycrystalline samples of median grain diameter 7.1, 7.2 and 7.8nm were sputtered and the temperature dependence of the coupling measured. Small changes in the AF grain diameter are reflected by large volume changes in the spin clusters and consequently the temperature dependence. In particular the variation of the coercivity with temperature affects the stability of the magnetization of the spin clusters.
  • A. Hirohata, L. R. Fleet, K. Yoshida, H. Kobayashi, Y. Kaneko, Y. Ohno ...
    2014 年 38 巻 2-2 号 p. 66-70
    発行日: 2014/03/01
    公開日: 2014/03/20
    [早期公開] 公開日: 2014/02/19
    ジャーナル オープンアクセス
      There has been significant controversy over the spin-polarised electron transport across Fe/GaAs(001) interfaces, particularly concerning the non-reproducible changes in the spin polarisation. We first overview these previous reports and then provide a solution using abrupt Fe/GaAs(001) interfaces. We demonstrate that an Fe monolayer at the interface controls the spin transport properties and show that abrupt interfaces do not allow sign changes in their injected spin polarisation. The abrupt interface offers reproducible spin transport properties, agreeing with our calculations based on the experimentally observed atomic interface structure. Such junctions are therefore ideal for future spin-transistor applications.
  • A. Pratt, M. Kurahashi, X. Sun, Y. Yamauchi
    2014 年 38 巻 2-2 号 p. 71-74
    発行日: 2014/03/01
    公開日: 2014/03/20
    [早期公開] 公開日: 2014/02/19
    ジャーナル オープンアクセス
      Here we give an overview of how a spin-polarized metastable helium beam may be used to characterize surfaces and interfaces relevant to spin injection from a ferromagnetic (FM) electrode to an organic semiconductor (OSC). Taking advantage of the extreme surface sensitivity of this technique, we show how information regarding the electronic and magnetic properties of FM/OSC interfaces may be obtained. We demonstrate how the spin polarization at the surface of a FM oxide―Fe3O4(001)―may be drastically enhanced through atomic adsorption. We also investigate the adsorption of copper phthalocyanine (CuPc) on Fe3O4(001) revealing that the CuPc molecular orbitals are spin polarized due to the magnetic interaction with the substrate, even for a relatively thick film of 5 nm.
  • Jun’ichi Ieda, Sadamichi Maekawa
    2014 年 38 巻 2-2 号 p. 75-77
    発行日: 2014/03/01
    公開日: 2014/03/20
    [早期公開] 公開日: 2014/02/19
    ジャーナル オープンアクセス
      The spinmotive force, a mechanism of energy-transfer from magnetization into conduction electrons, in ferromagnetic metals has recently been proposed. The basic concepts and recent progress of the spinmotive force are presented.
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