[111]-strained spin ice: Localization of thermodynamically deconfined monopoles

TL;DR

This study investigates how uniaxial strain affects monopole excitations in classical spin ice, revealing conditions under which monopoles remain deconfined, localize, or become sub-dimensional, with implications for experimental detection.

Contribution

It demonstrates that uniaxial strain preserves Coulomb phase and monopole deconfinement in spin ice, while strain sign and additional dynamics induce monopole localization or sub-dimensional behavior.

Findings

Monopoles remain deconfined under strain preserving ice degeneracy.

Negative strain leads to monopole diffusion at low temperatures.

Positive strain causes monopole localization, affecting magnetic noise spectra.

Abstract

We study classical spin ice under uniaxial strain along the $[111]$ crystallographic axis. Remarkably, such strain preserves the extensive ice degeneracy and the corresponding classical Coulomb phase. The emergent monopole excitations remain thermodynamically deconfined exactly as in the isotropic case. However, their motion under local heat bath dynamics depends qualitatively on the sign of the strain. In the low-temperature limit for negative strain, the monopoles diffuse, while for positive strain, they localize. Introducing additional ring exchange dynamics into the ice background transforms the localized monopoles into sub-dimensional excitations whose motion is restricted to diffusion in the $(111)$-plane. The phenomena we identify are experimentally accessible in rare-earth pyrochlores under uniaxial pressure as well as in tripod kagome materials. The diffusive versus localized nature of the monopoles manifests in characteristic magnetic noise spectra, which we compute.