Spin Injection from Magnetic Thin Films into InGaAs Quantum Wells

The injection of spin polarised electrons into semiconductors is a fundamental§challenge in the emergent field of spin electronics. This work is§an investigation into spin injection from magnetic thin film contacts§into (100) GaAs/InGaAs quantum wells in spin light emitting diodes§(spin LEDs). This structure is relevant to many quantum dot device§layers. The spin injection characteristics are examined as a function of photon energy, magnetic field, applied bias, external§optical efficiency and temperature.§Further, the Heusler alloys Co2TiSn and Co2CrAl are investigated§through ab initio electronic structure calculations as potentially highly§polarised spin injectors. Pronounced minority spin band gaps were found in these alloys§and while majority spins are metallic, minority spins undergo hole-like§dispersion near the Fermi level. §While spin injection is observed from both Heusler alloy and Fe injectors, Fe is a more§efficient spin injector and gives room temperature results. The bias§dependent spin injection shows a decrease at higher voltages due to§hot electron spin transport in the semiconductor and shows similar§trends for both types of spin injector.