Interaction-driven Chern insulating phases in the [Formula: see text] lattice with Rashba spin-orbit coupling

Shi-Qing Lin; Hui Tan; Pei-Hao Fu; Jun-Feng Liu

doi:10.1016/j.isci.2023.107546

Interaction-driven Chern insulating phases in the $α - T_{3}$ lattice with Rashba spin-orbit coupling

iScience. 2023 Aug 7;26(9):107546. doi: 10.1016/j.isci.2023.107546. eCollection 2023 Sep 15.

Authors

Shi-Qing Lin¹, Hui Tan¹, Pei-Hao Fu^{1

2}, Jun-Feng Liu¹

Affiliations

¹ School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China.
² Science, Mathematics and Technology, Singapore University of Technology and Design, 8 Somapah Road, Singapore City 487372, Singapore.

Abstract

The magnetic interaction is a necessary ingredient to break the time-reversal symmetry in realizing quantum anomalous Hall, or Chern insulating phases. Here, we study topological phases in the $α - T_{3}$ model, a minimal theoretical model supporting the flat band, taking account of Rashba spin-orbit coupling and flat-band-induced spontaneous ferromagnetism. By analyzing the interaction-driven phase diagrams, band structures, topological edge states, and topological invariants, we demonstrate that this system offers a platform for realizing a wide range of phases, including normal insulators, semimetals, and Chern insulators. Uniquely, there exist both high-Chern-number insulators and valley-polarized Chern insulators. In the latter phase, edge channels exist in the single valley, leading to nearly $100 %$ valley polarization. These findings demonstrate the potential of interaction-driven systems in realizing exotic phases and their promising role in future applications in topology electronics and valleytronics.

Keywords: Condensed matter physics; Magnetism; Nanomaterials.