High-pressure study of antiferromagnetic order in CePd 2(Al,Ga) 3

Abstract

The pressure effects on the antiferromagnetic order in CePd 2(Al 1- x Ga x ) 3 for x = 0.01 and 0.05 has been studied by specific heat measurements under pressure. It was found that antiferromagnetic order temperature T N increased initially with increasing pressure, then passed through a maximum and decreased at higher pressures. The pressure P max, which gives rise to the maximum T N, increased with the increase of Ga content. For x = 0.01, P max equals 1.0 GPa, while for x = 0.05, P max is 1.2 GPa. These results have been discussed in terms of the variation of the exchange coupling between the 4f and conduction electrons estimated from the pressure dependence of lattice constants. An interpretation has been given on the basis of Doniach phase diagram. This interpretation also indicates that the hybridization of the p electrons with 4f electrons played an important part in determining the antiferromagnetic order in the CePd 2Al 3 compound.