Structural, electronic, magnetic, and thermal properties of single-crystalline UNi0.5Sb2

TL;DR

This study investigates the structural, magnetic, electronic, and thermal properties of single-crystalline UNi0.5Sb2, revealing its antiferromagnetic transition at 161 K, pressure effects on transition temperatures, and additional low-temperature features related to Fermi surface and hybridization effects.

Contribution

First comprehensive analysis of UNi0.5Sb2's properties including neutron diffraction, magnetic susceptibility, and thermal measurements under pressure, revealing new low-temperature features.

Findings

UNi0.5Sb2 is tetragonal with U-moments ~1.85 μB.

Antiferromagnetic transition at 161 K increases with pressure.

Additional features at 40 and 85 K relate to Fermi surface effects.

Abstract

We studied the properties of the antiferromagnetic (AFM) UNi0.5Sb2 (TN \approx 161 K) compound in Sb-flux grown single crystals by means of measurements of neutron diffraction, magnetic susceptibility ({\chi}), specific heat (Cp), thermopower (S), thermal conductivity ({\kappa}), linear thermal expansion ({\Delta}L/L), and electrical resistivity ({\rho}) under hydrostatic pressures (P) up to 22 kbar. The neutron diffraction measurements revealed that the compound crystallizes in the tetragonal P42/nmc structure, and the value of the U-moments yielded by the histograms at 25 K is \approx 1.85 \pm 0.12 {\mu}B/U-ion. In addition to the features in the bulk properties observed at TN, two other hysteretic features centered near 40 and 85 K were observed in the measurements of {\chi}, S, {\rho}, and {\Delta}L/L. Hydrostatic pressure was found to raise TN at the rate of \approx 0.76 K/kbar, while suppressing the two low temperature features. These features are discussed in the context of Fermi surface and hybridization effects.