4f Hybridization effect on the magnetism of Nd₂PdSi₃

Abstract

Among the members of the series R₂PdSi₃ (R= Rare-earths), the magnetic behavior of the Nd compound is interesting in some respects. This compound is considered to order ferromagnetically (below 16 K), unlike other members of this series which order antiferromagnetically. In addition, magnetic ordering temperature (T_o) is significantly enhanced with respect to de Gennes scaled value. In order to understand the magnetism of this compound better, we have investigated the magnetic behavior in detail (under external pressure as well) and also of its solid solutions based on substitutions at Nd and at Si sites, viz., on the series, Nd_2-x(Y,La)_xPdSi_3-yGe_y (x, y= 0.2, 0.4, 0.8, and 1.2) by bulk measurements. The results overall establish that Nd₂PdSi₃ orders ferromagnetically below 16 K, but antiferromagnetic component seems to set in at very low temperatures. Notably, there is a significant suppression of T_o for Y and Ge substitutions, compared to La substitution, for a given magnitude of unit-cell volume change, however qualitatively correlating with the separation between the layers of Nd and Pd-Si(Ge). On the basis of this observation, we conclude that 4f(Nd) hybridization plays a major role on the magnetism of the former solid solutions. To our knowledge, this work serves as a rare demonstration of 4f-hybridization effects on the magnetism of a Nd-based intermetallic compound.