Complex magnetic phase diagram of CePd_{2-x}Ni_xAl_3 around its critical concentration

Abstract

Thermal, magnetic and transport measurements are reported on CePd_{2-x}Ni_xAl_3 in the 0<= x <= 1 range, including the effect of pressure (p) and magnetic field on some selected samples. The low temperature results indicate that long range antiferromagnetic order is stable up to x=0.2, while between 0.25 and 0.5 magnetic disorder gives rise to non-Fermi-liquid (NFL) behavior. In this region, the low temperature specific heat can be described by the sum of two components, the major one showing a C_P/T=gamma_0 -gamma_1 T^(1/2) dependence, while the minor one includes a decreasing number of degrees of freedom related to a residue of short range order. The latter extrapolates to zero between 0.45<x_{cr}<0.5. Electrical resistivity (rho) studies performed under pressure for x=0.5 allow to investigate the evolution of the NFL state right above the critical point, where the exponent of rho ~ T^n is found to increase from n=1 (for p=0) up to n=2 (for p=12 kbar). The latter is observed for x=1.0 already at normal pressure, indicating the onset of the Fermi Liquid behavior. Doping and pressure effects are compared by fitting high temperature resistivity data employing a unique function which allows to describe the evolution of the characteristic energy of this series through a large range of concentration and pressure.