Valence instability across the magnetostructural transition in USb2

Abstract

We have performed pressure dependent X-ray diffraction and resonant X-ray emission spectroscopy experiments on USb2 to further characterize the AFM-FM transition occuring near 8 GPa. We have found the magnetic transition coincides with a tetragonal to orthorhombic transition resulting in a 17% volume collapse as well as a transient f -occupation enhancement. Compared to UAs2 and UAsS, USb2 shows a reduced bulk modulus and transition pressure and an increased volume collapse at the structural transition. Except for an enhancement across the transition region, the f -occupancy decreases steadily from 1.96 to 1.75.