Nonrelativistic Spin-Momentum Coupling in Antiferromagnetic Twisted Bilayers

Spin-momentum coupling, which depends strongly on the relativistic effect of heavy elements in solids, is the basis of many phenomena in spintronics. In this Letter, we theoretically predict nonrelativistic spinmomentum coupling in two-dimensional materials. By proposing magnetic symmetry requirements for spin splitting in two-dimensional systems, we find that a simple twisting operation can realize nonrelativistic spin splitting in antiferromagnetic bilayers. Through first-principles calculations, we demonstrate that momentum-dependent spin splitting exists extensively in antiferromagnetic twisted bilayers with different crystal structures and twist angles. The size of the spin splitting caused by twisting is of the same order of magnitude as that arising from spin-orbit coupling. In particular, a transverse spin current with an extremely high charge-spin conversion ratio can be generated in twisted structures under an external electric field. The findings demonstrate the potential for achieving electrically controlled magnetism in materials without spin-orbit coupling.

Automated summary

In this study, nonrelativistic spin-momentum coupling is predicted in two-dimensional materials. Twist operations in antiferromagnetic bilayers can induce spin splitting comparable to spin-orbit coupling, and generate a transverse spin current with a high charge-spin conversion ratio. These findings demonstrate the potential for achieving electrically controlled magnetism in materials without spin-orbit coupling.