Heavy fermion behavior in the magnetic to nonmagnetic transition of U(In,Sn)₃

Abstract

The UX₃ systems with X = Ga, In, Tl, Si, Ge, Sn and Pb are a particularly interesting class of uranium compounds because both their magnetic and electronic properties are drastically influenced by f-spd hybridization. We report resistivity, low temperature specific heat, magnetic susceptibility and high field magnetization results for the U(In_1−xSn_x)₃ is an enhanced paramagnetic system and UIn₃ orders antiferromagnetically with a Néel temperature, T_n, equal to 108 K. Upon dilution of USn₃ by UIn₃, the electronic coefficient of the specific heat, γ, as well as the zero temperature limit of the magnetic susceptibility, χ(0), increase dramatically with γ at T = 1.3 K reaching a value of 520 mJ/mol K² for x = 0.6. For x = 0.6, both γ and χ(0) decrease and for x = 0.45 the system magnetically orders. The study of a U system represents the first systematic study of the transition from a paramagnetic state to a heavy fermion state followed by a transition to a long ranged magnetically ordered state. The results for U(In,Sn)₃ will be presented and discussed in terms of relevant theories.