Catalog of C -Paired Spin-Momentum Locking in Antiferromagnetic Systems

Antiferromagnetic materials (AFMs) have been gaining lots of attention due to their great potential in spintronics devices and the recently discovered novel spin structure in the momentum space, i.e., C-paired spin-valley or spin-momentum locking (CSML), where spins and valleys or momenta are locked to each other due to the crystal symmetry guaranteeing zero magnetization. Here, we systematically study CSMLs and propose a general theory and algorithm using little cogroup and coset representatives, which reveals that 12 elementary kinds of CSMLs, determined by the geometric relation of spins and valleys and the essential symmetry guaranteeing zero magnetization, are sufficient to fully represent all possible CSMLs. By combining the proposed algorithm and high-throughput first-principles calculations, we predict 38 magnetic point groups and identify 142 experimentally verified AFMs that can realize CSML. Besides predicting new materials, our theory can naturally reveal underlying mechanisms of CSMLs’ responses to external fields. As an example, two qualitatively different types of piezomagnetism via occupation imbalance or spin tilting are predicted in RbV2Te2O. The algorithm and conclusions can be directly extended to the locking between valley or momentum and any other pseudovector degree of freedom, e.g., Berry curvature, as exemplified in RbV2Te2O and the new proposed piezo-Hall effect, where a strain can induce a nonzero anomalous Hall conductance. In addition, the proposed concept and methodology can be straightforwardly applied to other symmetry groups, such as spin group. Published by the American Physical Society 2025