Prediction of single-layer TiVI6 as a promising two-dimensional valleytronic semiconductor with spontaneous valley polarization

Abstract

Spontaneous valley polarization in two-dimensional lattices is of fundamental importance as it provides novel opportunities for information related applications. Although highly valuable, currently, the realization of spontaneous valley polarization still remains a challenge. Here, we report the development of a promising two-dimensional valleytronic semiconductor in single-layer TiVI₆. Using first-principles calculations, we show that single-layer TiVI₆ exhibits both spin and valley polarizations spontaneously. The spontaneous valley polarization in the valence band reaches up to 22 meV. The strong magnetic exchange interaction and large spin–orbital coupling are studied to understand the physics underlying this phenomenon. We further reveal that this system could demonstrate the anomalous valley Hall effect. More importantly, we reveal that the existence/nonexistence of the valleys and even the anomalous valley Hall effect in this system could be controlled via strain, offering a promising strategy for realizing controllable valleytronic devices.