Hybrid magnetic/semiconduct or spintronic materials and devices

We report our experimental studies of different kinds of magnetic/semiconductor hybrid materials and devices highly promising for the next generation spintronics. The epitaxial Fe films on three III-V semiconductor surfaces, InxGa1-xAs(1 0 0), x = 0, 1, 0.2, show a uniaxial magnetic anisotropy in the ultrathin region. This suggests that both interface bonding and the magnetoelastic effect control magnetic anisotropy. We demonstrate the epitaxial growth of new hybrid spintronic structures, namely, Fe3O4/GaAs and Fe3O4/MgO/GaAs, where the magnetic oxide has both high Curie temperature and high spin polarisation. Both the magnetisation loops and magneto-resistance curves of Fe3O4/GaAs were found to be dominated by a strong uniaxial magnetic anisotropy. We have also fabricated a novel vertical hybrid spin device, i.e. Co(15 ML)/GaAs(50 nm, n-type)/Al0.3Ga0.7As(200 nm, n-type)/FeNi(30 nm) and observed for the first time a change of the magneto-resistance up to 12% by direct transport measurements. which demonstrated large spin injection and the feasibility to fabricate the spin-transistors capable of operating at room temperatures by using magnetic/semiconductor hybrid materials. (C) 2006 Elsevier B.V. All rights reserved.