Spin pumping and spin-transfer torques in antiferromagnets

Area of Science:

• Condensed Matter Physics
• Spintronics
• Materials Science

Background:

• Spin pumping and spin-transfer torques are established phenomena in ferromagnetic materials.
• The study of these phenomena in antiferromagnetic materials remains underexplored.
• Understanding spin dynamics in antiferromagnets is crucial for next-generation spintronic devices.

Purpose of the Study:

• To investigate spin pumping from antiferromagnetic materials.
• To establish the relationship between spin pumping and current-induced torques in antiferromagnets.
• To derive expressions for pumped spin and staggered spin currents.

Main Methods:

• Utilizing theoretical calculations based on electron scattering at a normal metal-antiferromagnetic interface.
• Deriving pumped spin and staggered spin currents using Onsager reciprocity relations.
• Analyzing the influence of staggered field, magnetization, and their rates of change.

Main Results:

• Derived expressions for pumped spin and staggered spin currents in antiferromagnets.
• Demonstrated that spin pumping in antiferromagnets is comparable in magnitude to that in ferromagnets.
• Showed that the direction of pumped currents is controllable by the polarization of the driving microwave.
• Established a connection between pumped currents and current-induced torques via Onsager reciprocity.

Conclusions:

• Spin pumping is a viable phenomenon in antiferromagnetic materials.
• The derived pumped currents are directly linked to current-induced torques, offering new avenues for spintronic applications.
• This work provides a theoretical foundation for exploring antiferromagnetic spintronics.