摘要
2D spontaneous valley polarization attracts great interest both for its fundamental physics and for its potential applications in advanced information technology,but it can only be obtained from inversion asymmetric single-layer crystals,while the possibility to create 2D spontaneous valley polarization from inversion symmetric single-layer lattices remains unknown.Here,starting from inversion symmetric single-layer lattices,a general design principle for realizing 2D spontaneous valley polarization based on van der Waals interaction is mapped out.Using first-principles calculations,we further demonstrate the feasibility of this design principle in a real material of T-FeCl2.More remarkably,such design principle exhibits the additional exotic out-of-plane ferroelectricity,which could manifest many distinctive properties,for example,ferroelectricity-valley coupling and magnetoelectric coupling.The explored design-guideline and phenomena are applicable to a vast family of 2D materials.Our work not only opens up a platform for 2D valleytronic research but also promises the fundamental research of coupling physics in 2D lattices.
基金
This work is supported by the National Natural Science Foundation of China(No.12074217)
Shandong Provincial Natural Science Foundation(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)
Shandong Provincial Science Foundation for Excellent Young Scholars(No.ZR2020YQ04)
Qilu Young Scholar Program of Shandong University,and Taishan Scholar Program of Shandong Province.