Spin relaxation induced by interfacial effects in n-GaN/MgO/Co spin injectors

Area of Science:

• Spintronics
• Semiconductor Physics
• Materials Science

Background:

• Interfacial effects critically influence spin relaxation, impacting electrical spin injection and transport in semiconductor spintronics.
• Understanding and controlling spin relaxation mechanisms are essential for advancing spintronic device performance.

Purpose of the Study:

• To investigate interface-related spin relaxation during electrical spin injection into n-GaN.
• To explore methods for prolonging spin relaxation times in GaN-based spintronic devices.

Main Methods:

• Electrical spin injection into n-GaN using an n-GaN/MgO/Co tunnel barrier.
• Investigation of spin relaxation using electrical Hanle effect measurements.
• Characterization of spin relaxation dynamics via time-resolved Kerr rotation (TRKR) spectroscopy.

Main Results:

• Interfacial random magnetostatic fields contribute significantly to spin relaxation at low temperatures (<80 K) and can be reduced by a smoother interface.
• Even after suppressing magnetostatic fields, spin relaxation times were shorter than bulk values, attributed to interface-induced Rashba spin-orbit coupling (SOC).
• Interfacial Rashba SOC-induced spin relaxation is suppressed at higher temperatures (>50 K) due to thermal activation.

Conclusions:

• Achieved spin relaxation times as long as 300 ps in GaN.
• Demonstrated that engineering interfacial effects can significantly prolong spin relaxation times.
• Findings provide insights for developing advanced GaN-based spintronic devices utilizing their direct and wide bandgap properties.