Increase in spin injection efficiency of a CoFeMgO (100) tunnel spin injector with thermal annealing

Postgrowth thermal annealing of a CoFeMgO (100) tunnel spin injector grown on a GaAsAlGaAs quantum well structure results in a significantly increased spin injection efficiency as inferred from the polarization of heavy-hole electroluminescence from a quantum well optical detector. The as-deposited sample displayed an initial polarization at 100 K of 43%, which was increased to 52% after a 1 h anneal at 300 °C, and finally to 55% after a second 1 h anneal at 340 °C. The polarization remained unchanged upon further annealing to temperatures as high as 400 °C. These results show that tunnel spin injectors based on CoFeMgO are robust with high thermal stability, making them useful for device applications. © 2005 American Institute of Physics.