Orbital Chern Insulator at $\nu=-2$ in Twisted MoTe$_{2}$

TL;DR

This paper predicts a gate-tunable orbital Chern insulator at hole filling  in twisted MoTe2, with a topological phase diagram that can be controlled by interlayer bias, enabling magnetic and topological state switching.

Contribution

It introduces a new orbital Chern insulating state at  in twisted MoTe2, with a gate switchable Chern number and orbital magnetization, expanding understanding of topological phases in 2D materials.

Findings

The  state exhibits a topological phase diagram with Chern number , 0, and +1 controlled by interlayer bias.

The  state has a sizable orbital magnetization that can be switched by gate voltage.

The state is stabilized in an antiferromagnetic background, enabling magnetic field control of topological properties.

Abstract

In twisted MoTe$_{2}$, latest transport measurement has reported observation of quantum anomalous Hall effect at hole filling $\nu=-1$, which undergoes a topological phase transition to a trivial ferromagnet as layer hybridization gets suppressed by interlayer bias $D$. Here we show that this underlies the existence of an orbital Chern insulating state with gate ($D$) switchable sign in an antiferromagtic spin background at hole filling $\nu=-2$. From momentum-space Hartree Fock calculations, we find this state has a topological phase diagram complementary to that of the $\nu=-1$ one: by sweeping $D$ from negative to positive, the Chern number of this $\nu=-2$ state can be switched between $+1$, $0$, and $-1$, accompanied by a sign change of a sizable orbital magnetization. In range of $D$ where this antiferronagnet is the ground state, the orbital magnetization allows magnetic field initialization of the spin antiferromagnetic order and the Chern number.