Nonequilibrium Antiferromagnetic State in the Heavy Electron Compound URu_2Si_2

TL;DR

This study explores how uniaxial stress induces a metastable antiferromagnetic phase in URu2Si2, revealing a first-order transition and the significance of crystalline strain in phase competition.

Contribution

It provides new insights into stress-induced magnetic phase transitions and the role of lattice strain in URu2Si2, highlighting the metastability of the AF phase.

Findings

AF Bragg-peak intensity exhibits hysteresis under stress.

Stress induces a metastable AF phase separated by a first-order transition.

Crystalline strain, especially the c/a ratio, influences phase competition.

Abstract

We have investigated the nature of the antiferromagnetic (AF) phase induced by uniaxial stress sigma in URu2Si2, by performing elastic neutron scattering measurements up to 0.4 GPa. We have found that the AF Bragg-peak intensity shows a clear hysteresis loop with sigma under the zero-stress cooling condition. The result strongly suggests that the sigma-induced AF phase is metastable and separated from the coexisting "hidden ordered" phase by a first-order phase transition. We also present the analyses of the crystalline strain effects, and suggest that the c/a ratio plays an important role in the competition between these two phases.