摘要
Exploring two-dimensional valleytronic crystals with large valley-polarized state is of considerable importance due to the promising applications in next-generation information related devices.Here,we show first-principles evidence that single-layer NbX_(2)(X=S,Se)is potentially the long-sought two-dimensional valleytronic crystal.Specifically,the valley-polarized state is found to occur spontaneously in single-layer NbX_(2),without needing any external tuning,which arises from their intrinsic magnetic exchange interaction and inversion asymmetry.Moreover,the strong spin-orbit coupling strength within Nb-d orbitals renders their valley-polarized states being of remarkably large(NbS_(2)∼156 meV/NbSe_(2)∼219 meV),enabling practical utilization of their valley physics accessible.In additional,it is predicted that the valley physics(i.e.,anomalous valley Hall effect)in single-layer NbX_(2) is switchable via applying moderate strain.These findings make single-layer NbX_(2) tantalizing candidates for realizing high-performance and controllable valleytronic devices.
基金
This work is supported by the National Natural Science Foundation of China(No.11804190)
Shandong Provincial Natural Science Foundation of China(Nos.ZR2019QA011 and ZR2019MEM013)
Shandong Provincial Key Research and Development Program(Major Scientific and Technological Innovation Project)(No.2019JZZY010302)
Shandong Provincial Key Research and Development Program(No.2019RKE27004)
Qilu Young Scholar Program of Shandong University,and Taishan Scholar Program of Shandong Province.