Magnetic anisotropy in uranium monosulfide, probed by the magnetic torque measurements

TL;DR

This study investigates the magnetic anisotropy of uranium monosulfide using torque measurements, revealing strong anisotropic behavior in both paramagnetic and ferromagnetic phases linked to crystal defects, quadrupolar interactions, and magneto-elastic effects.

Contribution

It provides detailed insights into the anisotropic magnetic properties of US, highlighting the similarity between paramagnetic and ferromagnetic phases and suggesting a magneto-elastic origin.

Findings

US exhibits the largest magneto-crystalline anisotropy in cubic systems.

Anisotropy directions are <100> hard, <111> easy, <110> intermediate.

Paramagnetic and ferromagnetic anisotropies are similar, indicating strong magneto-elastic coupling.

Abstract

We have studied the magnetic torque in uranium monosulfide (US) single crystals to explore the magnetic anisotropy in this material. Uranium monosulfide crystallizes in cubic, NaCl-type of crystal structure and exhibits the largest magneto-crystalline anisotropy observed in cubic systems. By performing detailed torque measurements we observe a strongly anisotropic behavior in the paramagnetic phase due to crystal defects and quadrupolar pair interactions. Our studies also confirm the presence of a large anisotropy in the ferromagnetic state of the US system with the <100>, <111>, and <110> directions being hard, easy, and intermediate axis, respectively. Furthermore, the anisotropy in the paramagnetic phase shows similar characteristics to the anisotropy observed in the ferromagnetic phase, as characterized by second and fourth rank susceptibility terms. The similarity of the anisotropic behaviors in paramagnetic and ferromagnetic phases is the consequence of strong magneto-elastic properties in this system, which possibly lead to the rhombohedral structural distortion, not only in the ferromagnetic phase but also in the paramagnetic phase (induced by applied magnetic fiield).