Chern-Textured Exciton Insulators with Valley Spiral Order in Moir\'e Materials

TL;DR

This paper investigates Chern texture insulators in moiré materials, revealing a new valley-ordered phase with nontrivial topology that emerges as a competitive ground state in certain systems.

Contribution

It introduces the concept of Chern texture insulators with valley spiral order and demonstrates their emergence through Hartree-Fock calculations in specific moiré systems.

Findings

Chern texture insulators are energetically competitive in certain moiré systems.

Valley order parameter textures are linked to band topology.

The phase appears in systems lacking twofold rotation symmetry.

Abstract

We explore the phase diagrams of moir\'e materials in search of a new class of intervalley-coherent correlated insulating state: the Chern texture insulator (CTI). This phase of matter, proposed in a companion paper, breaks valley $U(1)$ symmetry in a nontrivial fashion wherein the valley order parameter is forced to texture in momentum space as a consequence of band topology. Using detailed Hartree-Fock studies, we establish that the CTI emerges as an energetically competitive intermediate-coupling ground state in several moir\'e systems which lack a twofold rotation symmetry that forbids the single-particle topology essential to the formation of the CTI valley texture.