Highly spin-polarized room-temperature tunnel injector for semiconductor spintronics using MgO(100)

Area of Science:

• Solid State Physics
• Materials Science
• Quantum Electronics

Background:

• Efficient spin injection is crucial for spintronic devices.
• Understanding spin transport in semiconductors is essential for device performance.

Purpose of the Study:

• To quantify spin polarization and injection efficiency in GaAs from a CoFe/MgO(100) tunnel injector.
• To investigate the temperature dependence of spin polarization and its relation to spin relaxation.

Main Methods:

• Electrical injection of spin-polarized current into GaAs.
• Detection of spin polarization via electroluminescence polarization from GaAs/AlGaAs quantum wells.
• Measurement of polarization under a 5 T perpendicular magnetic field at varying temperatures (100 K and 290 K).

Main Results:

• Observed spin polarization of 57% at 100 K and 47% at 290 K.
• Determined spin injection efficiency of at least 52% at 100 K and 32% at 290 K.
• Identified a nonmonotonic temperature dependence of polarization, indicating spin relaxation effects.

Conclusions:

• CoFe/MgO(100) is an effective spin injector for GaAs.
• Spin relaxation in GaAs/AlGaAs quantum wells significantly impacts spin polarization at higher temperatures.
• Further optimization of materials and device structures is needed to mitigate spin relaxation for improved spintronic applications.