5d orbital induced room temperature quantum anomalous Hall effect in TbCl

Abstract

Following the experimental realization of Quantum anomalous Hall (QAH) effect in thin films of chromium-doped (Bi,Sb)₂Te₃, enhancing the work temperature of QAH effect has emerged as a significant and challenging task. Here we demonstrate monolayer TbCl as a promising candidate to realize the room temperature QAH effect. Using DFT+U method, double-checked by HSE06 and DMFT calculations, we identify the Hall conductivity G = −e²/h per layer in three-dimensional ferromagnetic insulator TbCl, which is a weakly stacked QAH layer. The monolayer TbCl inherits the magnetic and topological properties, exhibiting the QAH effect with Chern number C = −1. The large topological band gap reaches 42.8 meV, which is beyond room temperature. The extended 5d electrons lead to sizable exchange and superexchange interactions, resulting in a high Curie temperature T_c ~ 457 K. All these features demonstrate that monolayer TbCl will provide an ideal platform to realize the room temperature QAH effect.