Conductivity mismatch and voltage dependence of magnetoresistance in a semiconductor spin injection device

Magnetoresistance (MR) in a semiconductor spin injection and detection device is simulated by combining the formalisms for tunneling probabilities and spin polarized carrier diffusion. Thereby dependences of resistance and spin selectivity at the ferromagnet-semiconductor interface on voltage as well as on material parameters are determined. This leads to predicting the voltage dependence of MR of the overall ferromagnet-semiconductor device. It is found to be qualitatively similar to that of a magnetic tunnel junction. Similarly the dependence of the MR on the tunneling barrier height and thickness, and doping density are studied. Optimal material parameters for detection of spin polarized current are thus determined, which are helpful for designing experiments on spin injection into semiconductors.

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