Density wave halo around anyons in fractional quantum anomalous hall states

TL;DR

This paper predicts that localized anyons in fractional quantum anomalous Hall states induce a charge density wave halo, which can be used to indirectly measure their fractional charge via STM in moiré materials.

Contribution

It introduces a theoretical framework showing how anyons in FQAH states nucleate a detectable CDW halo, linking topological and broken symmetry orders.

Findings

Localized anyons induce a CDW halo with a larger spatial extent.

The CDW halo's properties depend on doping and magnetic field conditions.

Measurement of the CDW halo can reveal the fractional charge of anyons.

Abstract

The recent observation of fractional quantum anomalous Hall (FQAH) states in tunable moir\'e materials encourages study of several new phenomena that may be uniquely accessible in these platforms. Here, we show that an isolated localized anyon of the FQAH state will nucleate a `halo' of Charge Density Wave (CDW) order around it. We demonstrate this effect using a a recently proposed quantum Ginzburg-Landau theory that describes the interplay between the topological order of the FQAH and the broken symmetry order of a CDW. The spatial extent of the CDW order will, in general, be larger than the length scale at which the fractional charge of the anyon is localized. The strength and decay length of the CDW order around anyons induced by doping or magnetic field differs qualitatively from that nucleated by a random potential. Our results leverage a precise mathematical analogy to earlier studies of the superfluid-CDW competition of a system of lattice bosons which has been used to interpret the observed CDW halos around vortices in high-$T_c$ superconductors. We show that measurement of these patches of CDW order can give an indirect route to measuring the fractional charge of the anyon. Such a measurement may be possible by scanning tunneling microscopy (STM) in moir\'e systems.