Quantifying Spin-Orbit Torques in Antiferromagnet-Heavy-Metal Heterostructures

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Investigating spin currents' effect on magnetic order in insulating antiferromagnets (AFMs) is crucial for fundamental understanding and novel applications.
• Characterizing spin-orbit torques (SOTs) at AFM-heavy-metal (HM) interfaces is essential for developing spintronic devices.

Purpose of the Study:

• To determine the amplitudes of fieldlike and dampinglike SOTs at the interface between an easy-plane AFM, α-Fe_{2}O_{3}, and Platinum (Pt).
• To establish a direct method for characterizing SOTs in AFM-HM heterostructures.

Main Methods:

• Measuring the full angular dependence of harmonic Hall voltages in epitaxial c-axis oriented α-Fe_{2}O_{3}/Pt films.
• Modeling harmonic Hall signals alongside α-Fe_{2}O_{3} magnetic parameters.
• Utilizing out-of-plane field scans to determine the dampinglike torque component.

Main Results:

• The amplitudes of fieldlike and dampinglike SOTs were successfully determined.
• Fieldlike SOTs were found to be significantly larger than dampinglike SOTs.
• This dominance of fieldlike torques was correlated with a large imaginary component of the interface spin-mixing conductance.

Conclusions:

• A direct method for characterizing SOTs in AFM-HM heterostructures was demonstrated.
• The findings provide insights into the nature of spin interactions at AFM interfaces, contrasting with ferromagnetic systems.