Diverse magnetic orders and quantum anomalous Hall effect in twisted bilayer MoTe2 and WSe2

TL;DR

This paper investigates how band topology influences magnetic orders and the quantum anomalous Hall effect in twisted bilayer MoTe2 and WSe2, revealing phase transitions and stability factors relevant for experiments.

Contribution

It identifies magnetic and topological phases in twisted TMD homobilayers and shows how band topology stabilizes ferromagnetism through enhanced magnetic anisotropy.

Findings

Discovery of multiple magnetic and topological phases.

Identification of phase transitions driven by displacement field.

Large magnon gap indicating thermal stability of ferromagnetism.

Abstract

Twisted homobilayer transition metal dichalcogenide (TMD) offers a versatile platform for exploring band topology, interaction-driven phases, and magnetic orders. We study the interaction-driven phases in twisted TMD homobilayers and their low-energy collective excitations, focusing on the effect of band topology on magnetism and its thermal stability. From Hartree-Fock theory of the continuum model, we identify several magnetic and topological phases. By tuning the displacement field, we find two phase transitions involving a change in topology and magnetism respectively. We analyze the magnon spectrum, revealing the crucial role of band topology in stabilizing 2D ferromagnetism by amplifying easy-axis magnetic anisotropy, resulting in a large magnon gap of up to 7meV. As the magnon gap is directly tied to the stability of the magnetic phase to thermal fluctuations, our findings have several important experimental implications.