摘要
The quantum anomalous Hall(QAH)effect in two-dimensional(2D)topological materials has attracted widespread attention due to its potential for dissipationless chiral edge transport without an external magnetic field,which is highly promising for low-power electronic applications.However,identifying materials that exhibit these properties remains particularly challenging,as only a limited number of such materials are known,raising the intriguing question of whether it is possible to induce the QAH effect in materials with ordinary properties through structural modifications.In this work,we grow an unreported 2D titanium selenide(Ti_(3)Se_(4))on a Cu(111)substrate using molecular beam epitaxy.Low-energy electron diffraction and scanning tunneling microscopy characterizations reveal a√7×√7 brick-like structure.First-principles calculations and X-ray photoelectron spectroscopy measurements confirm its composition to be Ti_(3)Se_(4).Our calculations further demonstrate that monolayer Ti_(3)Se_(4),in its grown form on Cu(111),has the potential to host the QAH effect.Interestingly,when we examine its freestanding form,the monolayer transitions from a QAH insulator candidate into a conventional semiconductor,despite only minor differences in their atomic structures.This transition enlightens us that subtle lattice adjustments can induce a transition from semiconductor to QAH properties in freestanding Ti_(3)Se_(4).This discovery provides a potential route to engineering practical materials that may exhibit the QAH effect.
基金
financial support from the National Key R&D Program of China(Nos.2019YFA0308500 and 2018YFA0305800)
the National Natural Science Foundation of China(Nos.61925111,61888102,11974422,and U23A6015)
CAS Project for Young Scientists in Basic Research(No.YSBR-003)
the Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDB28000000 and XDB30000000)
the Fundamental Research Funds for the Central Universities provided to University of Chinese Academy of Sciences and to Renmin University of China(No.22XNKJ30(W.J.))
the CAS Key Laboratory of Vacuum Physics.
