Possible inversion symmetry breaking in the $S=1/2$ pyrochlore Heisenberg magnet

TL;DR

This study uses advanced numerical methods to investigate the ground state of the $S=1/2$ pyrochlore Heisenberg antiferromagnet, revealing spontaneous inversion symmetry breaking and providing insights into its low-temperature phases.

Contribution

First direct numerical evidence of spontaneous inversion symmetry breaking in the $S=1/2$ pyrochlore Heisenberg antiferromagnet using large-scale DMRG calculations.

Findings

Robust spontaneous inversion symmetry breaking observed.

Ground-state energy estimated at -0.490(6) J per site.

Indication of a transition from a spin liquid to a symmetry-broken state at low temperatures.

Abstract

We address the ground-state properties of the long-standing and much-studied three-dimensional quantum spin liquid candidate, the $S=\frac 1 2$ pyrochlore Heisenberg antiferromagnet. By using $SU(2)$ density-matrix renormalization group (DMRG), we are able to access cluster sizes of up to 128 spins. Our most striking finding is a robust spontaneous inversion symmetry breaking, reflected in an energy density difference between the two sublattices of tetrahedra, familiar as a starting point of earlier perturbative treatments. We also determine the ground-state energy, $E_0/N_\text{sites} = -0.490(6) J$, by combining extrapolations of DMRG with those of a numerical linked cluster expansion. These findings suggest a scenario in which a finite-temperature spin liquid regime gives way to a symmetry-broken state at low temperatures.