Sample dependence of giant magnetocaloric effect in a cluster-glass system Ho5Pd2

In order to investigate the effect of vacancy on the magnetocaloric effect in Ho5Pd2, we have carried out X-ray diffraction, magnetization, and specific heat measurements in the rare-earth intermetallic compound Ho5+xPd2(−0.4 ≤ x ≤ 0.4). The maximum magnetic entropy change −ΔSmmax, the maximum adiabatic temperature change ΔTadmax, and the relative cooling power of Ho5+xPd2 take large values at x = 0−0.4 for the field change of 5 T. The paramagnetic Curie temperature θp increases with an increase of x. This fact suggests that the enhancement of ferromagnetic coupling among the correlated spins leads to the increase of magnetocaloric effect.