Spin-$\frac{1}{2}$ kagome Heisenberg antiferromagnet with strong breathing anisotropy

TL;DR

This study uses advanced tensor network simulations to explore how breathing anisotropy affects the quantum spin-liquid phase in the kagome Heisenberg antiferromagnet, revealing a transition to a nematic phase.

Contribution

It provides the first large-scale tensor network analysis of the breathing anisotropy's impact on the kagome quantum spin-liquid phase.

Findings

U(1) QSL remains stable up to large anisotropy

First-order transition to a lattice-nematic phase

Insights relevant for vanadium oxyfluoride experiments

Abstract

We study the zero-temperature phase diagram of the spin-$\frac{1}{2}$ Heisenberg model with breathing anisotropy (i.e., with different coupling strength on the upward and downward triangles) on the kagome lattice. Our study relies on large scale tensor network simulations based on infinite projected entangled-pair state and infinite projected entangled-simplex state methods adapted to the kagome lattice. Our energy analysis suggests that the U(1) algebraic quantum spin-liquid (QSL) ground-state of the isotropic Heisenberg model is stable up to very large breathing anisotropy until it breaks down to a critical lattice-nematic phase that breaks rotational symmetry in real space through a first-order quantum phase transition. Our results also provide further insight into the recent experiment on vanadium oxyfluoride compounds which has been shown to be relevant platforms for realizing QSL in the presence of breathing anisotropy.