Spin ice under pressure: symmetry enhancement and infinite order multicriticality

TL;DR

This paper investigates how uniaxial pressure affects spin ice, revealing a unique phase transition with mixed features due to emergent SU(2) symmetry, and discusses potential experimental realizations.

Contribution

It uncovers a novel phase transition in spin ice under pressure characterized by symmetry enhancement and multicriticality, combining features of both first- and second-order transitions.

Findings

Phase transition between Coulomb liquid and fully magnetized phase

Emergent SU(2) symmetry at the critical point

Divergent susceptibility and vanishing domain wall tension

Abstract

We study the low-temperature behaviour of spin ice when uniaxial pressure induces a tetragonal distortion. There is a phase transition between a Coulomb liquid and a fully magnetised phase. Unusually, it combines features of discontinuous and continuous transitions: the order parameter exhibits a jump, but this is accompanied by a divergent susceptibility and vanishing domain wall tension. All these aspects can be understood as a consequence of an emergent SU(2) symmetry at the critical point. We map out a possible experimental realisation.