Electric-field-tuned consecutive topological phase transitions between distinct correlated insulators in moire MoTe2/WSe2 heterobilayer

TL;DR

This study demonstrates electric-field-induced topological phase transitions in moire heterobilayers, revealing a sequence from a Mott insulator to a quantum anomalous Hall state and then to an antiferromagnetic state, with detailed experimental insights.

Contribution

First experimental observation of consecutive topological phase transitions driven by electric field in moire heterobilayers, linking correlated insulators with distinct topological orders.

Findings

Identified a transition from a Mott insulator to a ferromagnetic quantum anomalous Hall insulator.

Observed a subsequent transition to an antiferromagnetic, valley-coherent Mott insulator.

Revealed a critical metallic state during the charge-gap collapse.

Abstract

Consecutive topological phase transitions (TPTs) between strongly correlated electronic phases that differ simultaneously in symmetry breaking and topological order are of fundamental interest in condensed matter physics, yet are rarely realized experimentally. We report two consecutive electric-field-driven TPTs at half filling (nu = 1) in angle-aligned MoTe2/WSe2 moire heterobilayers. With increasing out-of-plane displacement field, a geometrically frustrated Mott insulator evolves into a ferromagnetic quantum anomalous Hall (QAH) Mott insulator, i.e., a spin-polarized topological Mott insulator without an observable charge-gap closure, and subsequently into an antiferromagnetic, valley-coherent Mott insulator (VC-AFM) accompanied by a continuous charge-gap collapse and the emergence of a critical metallic state. Layer-resolved magnetic circular dichroism (MCD), magneto-transport, and compressibility measurements jointly determine the phase diagram. The high-field evolution of the antiferromagnetic state reveals a metamagnetic-like transition at a critical field B*, above which a Chern insulating transport response reappears. Our results establish the MoTe2/WSe2 moire platform as a tunable realization of an extended Kane-Mele-Hubbard model hosting sequential correlation-topology-intertwined transitions.