U 2T 2X (T=Co, Ni, Rh, Pd, Ir, Pt; X=In, Sn) compounds in high magnetic fields

Abstract

High-field magnetization measurements are reviewed, performed on compounds with stoichiometry U 2T 2X (T=Co, Ni, Rh, Pd, Ir, Pt; X=In, Sn), up to 38 T in the High-Field Installation at the University of Amsterdam, up to 57 T in the High-Field Facility at Osaka University and, in some cases, up to 55 T in the National High Magnetic Field Laboratory, Los Alamos. Variations of the hybridization of the 5f-electron states with the d and p states of the surrounding ligands play a substantial role in the evolution of ground states ranging from Pauli-paramagnetic ground states (U 2Co 2In, U 2Rh 2In, U 2Ir 2In, U 2Pt 2In, U 2Co 2Sn, U 2Ir 2Sn) to long-range antiferromagnetic order with well-developed U moments (U 2Ni 2In, U 2Pd 2In, U 2Ni 2Sn, U 2Rh 2Sn, U 2Pd 2Sn, U 2Pt 2Sn). At relatively high magnetic fields, the antiferromagnetically ordered compounds undergo metamagnetic phase transitions, presumably to the forced ferromagnetic state. However, the magnetization steps corresponding to these transitions are usually small as well as the magnetization values at the highest fields. In all cases, in high fields, no tendencies to saturation are observed, which points to field-induced moments, on the U and/or on the transition-metal sites.