IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Magnetic Interfaces and Nanostructures Tuesday Sessions
       Session MI+EL-TuA

Paper MI+EL-TuA10
Structural and Magnetic Characterization of the Fe@sub x@Co@sub 1-x@ / GaAs(100) Interface

Tuesday, October 30, 2001, 5:00 pm, Room 110

Session: Spintronics II: Spin Injection & Transport
Presenter: B.D. Schultz, University of Minnesota
Authors: B.D. Schultz, University of Minnesota
L.C. Chen, University of Minnesota
A. Isakovic, University of Minnesota
J. Strand, University of Minnesota
P.A. Crowell, University of Minnesota
M.M.R. Evans, University of Wisconsin-Eau Claire
C.J. Palmstrom, University of Minnesota
Correspondent: Click to Email
Two distinct surface contributions to the magnetic anisotropy can be used to control the magnetic properties of thin films of bcc Fe@sub x@Co@sub 1-x@ grown on GaAs (100). On bare GaAs (100), the sp@sup 3@ bonding in the zincblende structure results in a two-fold surface symmetry of the gallium and arsenic bonding and a (2x4)/c(2x8) surface reconstruction for an arsenic surface coverage ~0.75 monolayers. This two-fold surface symmetry reduces the expected cubic four-fold magnetic anisotropy for Fe@sub 1-x@Co@sub x@ films to a strong uniaxial magnetic anisotropy. However, four-fold symmetry is restored in films grown with an interlayer of Sc@sub 1-y@Er@sub y@As(100), in which the rock-salt structure provides an unreconstructed surface. Initial STM images of 0.10 monolayer deposited Fe@sub x@Co@sub 1-x@ on GaAs(100) (2x4)/c(2x8) surface grown by MBE at 95°C indicate isolated clusters of atomic dimensions with preferential attachment along the arsenic dimer rows. The images also indicate that the (2x4)/c(2x8) reconstruction remains relatively undisturbed by the initial nucleation and growth at this coverage. The deposition of bcc Fe@sub x@Co@sub 1-x@ on Sc@sub y@Er@sub 1-y@As(100) indicates there is no preferred nucleation site for the Fe@sub x@Co@sub 1-x@ atoms on the unreconstructed surface. Control of the interfacial properties of ferromagnetic metals and semiconductors is important for optimizing spin dependent transport across these interfaces. Spin dependent ejection of photo generated carriers from GaAs(100) into Fe@sub x@Co@sub 1-x@ ferromagnetic metal contacts has recently been observed. This paper will emphasize the correlation between the structure and chemistry of the Fe@sub x@Co@sub 1-x@/GaAs and Fe@sub x@Co@sub 1-x@/Sc@sub 1-x@Er@sub x@As/GaAs interfaces, determined by STM, RHEED, LEED, XPS, RBS, XRD and TEM, and the magnetic and transport properties. Supported by: ONR-N/N00014-1-0233, DARPA N/N00014-99-1-1005, and NSF-MRSEC NSF/DMR-9809364.