Low-field octupoles and high-field quadrupoles in URu2Si2

TL;DR

This paper proposes a new crystal field model for URu2Si2 that explains the transition from octupolar order at low fields to quadrupolar order at high fields, aligning with experimental susceptibility data.

Contribution

It introduces a novel crystal field model supporting octupolar and quadrupolar orders in different field regimes of URu2Si2.

Findings

Supports T(beta)z octupolar order in low-field phase

Predicts quadrupolar order in high-field phase

Matches temperature dependence of magnetic susceptibility

Abstract

The recent experimental finding of large-amplitude antiferromagnetism induced by uniaxial strain shows that the "hidden" low-field order of URu2Si2 breaks time reversal invariance. We propose a new crystal field model which supports T(beta)z octupolar order in the low-field phase, and quadrupolar order in a disjoint high-field phase. The temperature dependence of the linear and third order magnetic susceptibility is in good agreement with the observed behavior.