Bias dependence of spin injection/transport properties of a perpendicularly magnetized FePt/MgO/GaAs structure

Abstract

We demonstrate injection and transport of perpendicularly spin-polarized electrons in an FePt/MgO/n-GaAs structure. Spin-polarized electrons were injected from a perpendicularly magnetized FePt layer into an n-GaAs layer through a MgO barrier and detected by spatially resolved Kerr rotation microscopy. By measuring the Hanle effect, we reveal that the injected/extracted spin polarizations drastically vary with bias voltages. A spin lifetime of 3.5 ns is obtained that is consistent with the result from pump-probe measurements. This direct observation of perpendicularly polarized spin injection and lateral transport is one step toward realizing future spintronic devices.