Detailed study of the CePd2-xNixAl3 magnetic phase diagram around its critical concentration

Abstract

Thermal, magnetic and transport measurements on CePd2−xNixAl3 alloys within the 0≤x≤1 range are reported, including applied pressure (p) and magnetic field on some selected samples. The low temperature results indicate that long range antiferromagnetic order is robust up to x = 0.2, whereas between 0.25 and 0.5 magnetic fluctuations give rise to non-Fermi-liquid (NFL) behaviour. In this critical region, the low temperature specific heat can be described as due to two components, the major showing a NFL Cp /T = γ0 − γ1 √T dependence, while the minor one includes a decreasing fraction of short range order degrees of freedom. The latter is only observed close to the critical point, xcr≈0.35. Electrical resistivity (ρ) studies performed under pressure for x = 0.5 allow us to investigate the evolution of the NFL state around and beyond xcr, where the exponent of ρ ∝ T n increases from n = 1 (for p = 0) up to n = 2 (for p = 12 kbar). This exponent is also observed at normal pressure on the x = 1.0 sample, indicating the onset of the Fermi liquid behaviour. Doping and pressure effects are compared by fitting high temperature resistivity data employing a unique function which allows us to describe the evolution of the characteristic energy of this series along a large range of concentration and pressure.