Spin polarized tunneling through single-crystal GaAs(001) barriers

We investigate spin-dependent transport through an epitaxial GaAs(001) barrier sandwiched between polycrystalline iron films. Electron transport through the barrier is dominated by quantum mechanical tunneling, demonstrated by a nonlinear I-V characteristic, an exponential dependence of the tunneling current on the barrier thickness and the temperature dependence of the current. Though small a clear tunneling magnetoresistance effect proves spin-dependent transport through the Fe-GaAs interface. The small size of the effect and the high-field magnetoresistance suggest that spin-flip scattering plays a decisive role in transport. (C) 2002 American Institute of Physics.