Test of ballistic spin-polarized electron transport across ferromagnet/semiconductor Schottky interfaces

We previously reported highly efficient spin detection associated with spin filtering at single layer ferromagnet (FM)/GaAs interfaces (NiFe, Co, and Fe as the FM) using photoexcitation at room temperature, confirming that the Schottky barrier acts as a tunnel barrier. In order to consider explicitly possible background effects, e.g., magnetic circular dichroism, we therefore prepared antiferromagnetic (AF) Cr/GaAs structures as reference, using the same growth techniques as used for the FM structures. The Cr/GaAs samples showed very good Schottky characteristics and the difference in the helicity-dependent photocurrent was found to be negligible, indicating that no spin filtering occurs at the AF Cr/GaAs interfaces. These combined results conclusively show that high efficient spin detection can be achieved at room temperature. (C) 2002 American Institute of Physics.