Nonrelativistic Spin-Momentum Coupling in Antiferromagnetic Twisted Bilayers

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Spin-momentum coupling is crucial for spintronics, typically relying on heavy elements and relativistic effects.
• Existing spintronic phenomena often depend on strong spin-orbit coupling.

Purpose of the Study:

• To theoretically predict and demonstrate nonrelativistic spin-momentum coupling in two-dimensional (2D) materials.
• To explore methods for achieving spin splitting without relying on heavy elements or strong spin-orbit coupling.

Main Methods:

• Theoretical proposal of magnetic symmetry requirements for spin splitting in 2D systems.
• First-principles calculations to investigate spin splitting in twisted antiferromagnetic bilayers.
• Analysis of momentum-dependent spin splitting and charge-spin conversion ratios.

Main Results:

• Demonstrated nonrelativistic spin splitting in twisted antiferromagnetic bilayers through a simple twisting operation.
• Observed momentum-dependent spin splitting across various crystal structures and twist angles.
• Showcased spin splitting comparable in magnitude to spin-orbit coupling effects.
• Generated transverse spin currents with high charge-spin conversion ratios in twisted structures.

Conclusions:

• Nonrelativistic spin-momentum coupling can be achieved in 2D materials via magnetic symmetry and twisting.
• Twisted antiferromagnetic bilayers offer a pathway to spintronic applications without heavy elements.
• Potential for electrically controlled magnetism in materials lacking significant spin-orbit coupling.