Large Magnetoresistance Effect Due to Spin Injection into a Nonmagnetic Semiconductor

A novel magnetoresistance effect, due to the injection of a spin-polarized electron current from a dilute magnetic into a nonmagnetic semiconductor, is presented. The effect results from the suppression of a spin channel in the nonmagnetic semiconductor and can theoretically yield a positive magnetoresistance of $100\%$, when the spin flip length in the nonmagnetic semiconductor is sufficiently large. Experimentally, our devices exhibit up to $25\%$ magnetoresistance.