The interface between a ferromagnetic metal and a semiconductor has presented some fascinating problems. Given that a transition metal ferromagnet such as Fe is an ideal "source" of spin-polarized electrons and that a semiconductor such as GaAs is in many ways an ideal "host," the problem of spin transport between the two types of materials is of fundamental interest. I will describe a series of recent experiments that have established how a Schottky barrier between iron and GaAs can be used as either a source or detector of spin-polarized electrons. We have been able to investigate spin injection, transport, and detection in simple devices consisting of two ferromagnetic contacts on a GaAs channel. We demonstrate explicitly that spin accumulation in the semiconductor channel occurs when a ferromagnetic electrode is used as either a source or a sink of electrons. I will explain how the spin accumulation at the drain can be detected electrically.
This work was done in collaboration with Scott Crooker, Madalina Furis, Xiaohua Lou, Christoph Adelmann, Darryl Smith, and Chris Palmstrom.
C. Adelmann, X. Lou, J. Strand, C. J. Palmstrom, and P. A. Crowell, "Spin Injection and Relaxation in Ferromagnet-Semiconductor Heterostructures," Phys. Rev. B 71 121301(R) (2005).
S. A. Crooker, M. Furis, X. Lou, C. Adelmann, D. L. Smith, C. J. Palmstrom, and P. A. Crowell, "Imaging spin injection and accumulation in lateral ferromagnet/semiconductor devices," Science 309, 2191(2005).