False Vacuum Decay in Flat-Band Ferromagnets: Role of Quantum Geometry and Chiral Edge States

TL;DR

This paper proposes a protocol to probe magnetization dynamics in flat-band ferromagnets, highlighting the roles of quantum geometry and chiral edge states, with relevance to twisted MoTe$_2$ and graphene systems.

Contribution

It introduces a novel method for studying magnetization dynamics and quantum geometry effects in flat-band ferromagnets using nonequilibrium protocols.

Findings

Quantum geometry influences magnetization dynamics in ferromagnetic metals.

Chiral edge modes can be dynamically accessed at domain walls.

The protocol is relevant for twisted MoTe$_2$ and graphene-based systems.

Abstract

Dynamical control of quantum matter is a challenging, yet promising direction for probing strongly correlated states. Motivated by recent experiments in twisted MoTe$_2$ that demonstrated optical control of magnetization, we propose a protocol for probing magnetization dynamics in flat-band ferromagnets. We investigate the nucleation and dynamical growth of magnetic bubbles prepared on top of a false vaccum in both itinerant ferromagnets and spin-polarized Chern insulators. For ferromagnetic metals, we emphasize the crucial role of a non-trivial quantum geometry in the magnetization dynamics, which in turn also provides a probe for the quantum metric. Furthermore, for quantum Hall ferromagnets, we show how properties of chiral edge modes localized at domain-wall boundaries can be dynamically accessed. Our work demonstrates the potential for nonequilibrium protocols to control and probe strongly correlated phases, with particular relevance for twisted MoTe$_2$ and graphene-based flat-band ferromagnets.