Magnetization and specific heat of CePd_1-xNi_xAl

CePdAl crystallizes in the hexagonal ZrNiAl-type structure (space group P6̄2m), where the magnetic Ce³⁺ ions form a network of equilateral triangles in the ab plane similar to the kagomé lattice. It is a well known antiferromagnetic heavy-fermion system with Néel temperature T_N=2.7K. Magnetization and specific-heat measurements performed on CePd_1-xNi_xAl polycrystals show that the antiferromagnetic order in the system is suppressed by Ni substitution. T_N is reduced to zero temperature at a Ni concentration x=0.144. At high temperatures the magnetization data follow a Curie-Weiss law. The Weiss temperature |Θ| is negative with Θ increasing with x possibly due to the increasing Kondo effect. Indeed, the Kondo temperature increases with x as documented by an analysis of the specific heat and magnetic entropy of CePd_1-xNi_xAl for the samples with x=0, 0.062, 0.097, and 0.144.