Pressure dependence of the magnetization of URu2Si2

TL;DR

This study investigates how hydrostatic pressure affects the magnetization of URu2Si2, revealing that key temperature scales are pressure-insensitive, but the magnetocaloric effect varies significantly with pressure and orientation, indicating similarities and differences between hidden order and antiferromagnetic phases.

Contribution

It provides detailed measurements of magnetization under pressure, highlighting the weak pressure dependence of characteristic scales and the anisotropic changes in the magnetocaloric effect in URu2Si2.

Findings

Characteristic temperatures are weakly pressure-dependent.

Magnetocaloric effect decreases along c-axis under pressure.

Magnetocaloric effect increases significantly along a-axis.

Abstract

The ground state of URu2Si2 changes from so-called hidden order (HO) to large-moment antiferromagnetism (LMAF) upon applying hydrostatic pressure in excess of 14 kbar. We report the dc-magnetization M(B,T,p) of URu2Si2 for magnetic fields B up to 12 T, temperatures T in the range 2 to 100 K, and pressure p up to 17 kbar. Remarkably, characteristic scales such as the coherence temperature T*, the transition temperature T0, and the anisotropy in the magnetization depend only weakly on the applied pressure. However, the discontinuity in dM/dT at T0, which measures the magnetocaloric effect, decreases nearly 50 % upon applying 17 kbar for M and B parallel to the tetragonal c-axis, while it increases 15-fold for the a-axis. Our findings suggest that the HO and LMAF phases have an astonishing degree of similarity in their physical properties, but a key difference is the magnetocaloric effect near T0 in the basal plane.