Strain-Valley Coupling in 2D Antiferromagnetic Lattice

Abstract

In recent years, 2D valley physics has attracted tremendous attention in both fundamental research and device applications. The search for a coupling valley with exotic physical properties can enable the exploration of novel quantum devices and is therefore of significant interest. Here, using model analysis, a novel mechanism is proposed that realizes strong coupling between strain and valley physics in a 2D antiferromagnetic honeycomb lattice in a controllable fashion. This idea is to modulate the exchange interactions through strain, thereby mediating the inversion and time-reversal symmetries. As valley physics are connected with the symmetries, this enables a strong strain-valley coupling. On the basis of first-principles calculations, the validity of this mechanism is further demonstrated in a series of single-layer systems, i.e., AuCl3, CrI3, and VPTe3, which are predicted to host valley polarization and anomalous valley Hall effect. The change in bonding angle is found to play a crucial role in mediating the exchange interaction and thus the strain-valley coupling process. The microscopic origin is also discussed. These explored phenomena and insights greatly enrich the valley physics and 2D materials research.