Elastic properties of hidden order in URu$_{\text2}$Si$_{\text2}$ are reproduced by a staggered nematic

TL;DR

This paper proposes a phenomenological mean field theory that models the hidden order in URu$_{ ext2}$Si$_{ ext2}$ as a staggered nematic, successfully reproducing key experimental features and phase diagram topology.

Contribution

It introduces a novel nematic-based model for the hidden order in URu$_{ ext2}$Si$_{ ext2}$, explaining experimental observations and phase transitions.

Findings

Reproduces the temperature-pressure phase diagram topology.

Explains elastic modulus response above the transition.

Describes orthorhombic symmetry breaking in high-pressure phase.

Abstract

We develop a phenomenological mean field theory describing the hidden order phase in URu$_{\text2}$Si$_{\text2}$ as a nematic of the $\text B_{\text{1g}}$ representation staggered along the $c$-axis. Several experimental features are reproduced by this theory: the topology of the temperature--pressure phase diagram, the response of the elastic modulus $(C_{11}-C_{12})/2$ above the transition at ambient pressure, and orthorhombic symmetry breaking in the high-pressure antiferromagnetic phase. In this scenario, hidden order is characterized by broken rotational symmetry that is modulated along the $c$-axis, the primary order of the high-pressure phase is an unmodulated nematic, and the triple point joining those two phases with the high-temperature paramagnetic phase is a Lifshitz point.