Spin injection and detection in MnAs/GaAs/InAs hybrid system on GaAs(111)B through lateral non-local spin valve measurement at varied temperature

We successfully confirmed spin injection and detection in the MnAs/GaAs/InAs hybrid system on GaAs(111)B through lateral nonlocal spin valve (NLSV) measurement at 1.5 K and 77 K. Surprisingly, we found larger NLSV signals at 77 K than that at 1.5 K. This seems to be interesting behavior compared to typical temperature dependent spin injection and detection study. We studied in depth the NLSV signals to extract spin parameters such as spin diffusion length and spin injection efficiency in the hybrid system. We found spin diffusion length to be ∼10 µm and ∼7 µm at 1.5 K and 77 K, respectively, and also found spin injection efficiency to be ∼1.6% and ∼2.5% at 1.5 K and 77 K, respectively. The reason behind higher injection efficiency at 77 K comes from better impedance matching between MnAs and InAs at 77 K than that at 1.5 K due to large temperature variation of MnAs resistivity.