Structural, magnetic and thermal properties of the substitution series Ce$_2$(Pd$_{1-x}$Ni$_x$)$_2$Sn

摘要

Structural, magnetization and heat capacity studies were performed onCe$_2$(Pd$_{1-x}$Ni$_x$)$_2$Sn ($0 \leq x \leq 1$) alloys. The substitution ofPd atoms by isoelectronic Ni leads to a change in the crystallographicstructure from tetragonal (for $x \leq 0.3$) to centered orthorhombic lattice(for $x \geq 0.4$). The volume contraction thorough the series is comparable tothe expected from the atomic size ratio between transition metal components.The consequent weak increase of the Kondo temperature drives the twotransitions observed in Ce$_2$Pd$_2$Sn to merge at $x = 0.25$. After about a 1%of volume collapse at the structural modification, the system behaves as aweakly magnetic heavy fermion with an enhanced degenerate ground state.Notably, an incipient magnetic transition arises on the Ni-rich size. Thisunexpected behavior is discussed in terms of an enhancement of the density ofstates driven by the increase of the $4f$-conduction band hybridization and theincipient contribution of the first excited crystal field doublet on the groundstate properties.