Magnetism and magnetocaloric effect in YNi 4 Si-type R Ni 4 Si ( R =Ce, Gd, Tb and Dy) compounds

Abstract

Abstract Magnetic properties and magnetocaloric effect of YNi 4 Si-type R Ni 4 Si ( R =Ce, Gd, Tb and Dy) compounds have been investigated. Magnetic measurements indicate the intermediate valence state of cerium in YNi 4 Si-type CeNi 4 Si. The magnetocaloric effect of GdNi 4 Si, TbNi 4 Si and DyNi 4 Si are calculated in terms of isothermal magnetic entropy change and they reach maximum values of −22.9 J/kg K, −13.5 J/kg K and −15.6 J/kg K for a field change of 140 kOe near ~28 K, 47 K and 27 K and they show maximum values of −12.7 J/kg K, −7.8 J/kg K and −9.3 J/kg K for a field change of 50 kOe near ~28 K, 42 K and 22 K, respectively. In contrast to GdNi 4 Si, the magnetization-field isotherms for TbNi 4 Si and DyNi 4 Si exhibit hysteresis loop at 2 K due to strong magnetocrystalline anisotropy.