Tricritical phenomena at the γ→α transition in Ce0.9-xLaxTh0.1 alloys

Abstract

The γ→α isostructural transition in the Ce0.9-xLaxTh0.1 system is measured as a function of La alloying using specific heat, magnetic susceptibility, resistivity, thermal expansivity or striction measurements. A line of discontinuous transitions, as indicated by the change in volume, decreases exponentially from 118 K to close to 0 K with increasing La doping, and the transition changes from being first-order to continuous at a critical concentration, xc0.14. At the tricritical point, the coefficient of the linear T term in the specific heat γ and the magnetic susceptibility increase rapidly near xc and approach large values at x=0.35 signifying that a heavy Fermi-liquid state evolves at large doping. The Wilson ratio reaches a value above 2 for a narrow range of concentrations near xc, where the specific heat and susceptibility vary most rapidly with the doping concentration. © 2006 The American Physical Society.