Interfacial Crystal Structures and Non-Local Spin Signals of Co2FeAl0.5Si0.5/n-GaAs Junctions

Abstract

We have investigated interfacial crystal structures and non-local spin signals $\Delta R$ of Co2FeAl0.5Si0.5 (CFAS)/n-GaAs junctions. Cross-sectional transmission electron microscopy observations indicated that with the exception of Ga diffusion into CFAS of the sample deposited at 400 °C, the interfacial structure of the junctions and defect density at the interface were not very different for different CFAS fabrication temperatures of the substrate ( $T_{\mathrm {CFAS}})$ . The obtained reflection high-energy electron diffraction patterns showed that all samples fabricated at $T_{\mathrm {CFAS}}$ varying from room temperature to 400 °C exhibited the L21 ordered structure in the vicinity of CFAS/n-GaAs junctions. It is found that the junctions with larger rectifying characteristic as indicated by the conduction ratio $G(0.5~ \text {V})/G(-0.5~ \text {V})$ show larger spin signal $\Delta R$ . This may strongly affect the spin injection/detection efficiency.