Magnetocaloric effect in a cluster-glass system Ho5Pd2-xNix

Abstract

In order to investigate the effect of chemical pressure on the large magnetocaloric effect in Ho5 Pd2, we conducted X-ray diffraction, magnetization, and specific heat measurements on Ho5Pd2-xNix(0≤ x ≤ 1.0) rare-earth intermetallic compounds. The linear x dependence of the lattice constant a suggests that Ni is replaced with Pd in the case of Ho5Pd2-xNix (0 ≤ x ≤ 0.5). The spin-glass transition temperature Tg and paramagnetic Curie temperature θP indicate a weak oscillatory x dependence. However, the magnetic entropy change - ΔSm and the relative cooling power (RCP) are rapidly suppressed with increasing x. These large reductions in - ΔSm and RCP cannot be explained only in terms of normal Ruderman-Kittel- Kasuya-Yoshida (RKKY)-type indirect exchange interactions.