Magnetocaloric effect across the metamagnetic transition in Dy5Si2Ge2 single crystal

Abstract

A single crystal of rare earth intermetallic compound Dy5Si2Ge2 (Orthorhombic, Space group Pnma) has been prepared by Czochralski method. Magnetization of Dy5Si2Ge2 single crystal has been measured with magnetic field applied (i) along b axis and (ii) parallel to ac plane. Although a same Neél temperature (TN) of ∼55K is obtained when 50 Oe field is applied along b axis and in ac plane, the magnitude of magnetization is substantially different. This TN value is close to the antiferromagnetic ordering temperature of polycrystalline Dy5Si2Ge2 as well. The magnetization vs field data at 1.8K shows an ultra-sharp metamagnetic transition when field is applied along both the directions, in a critical field of about 28 kOe. It is observed that b axis is easy direction of magnetization. Magnetocaloric effect of this Dy5Si2Ge2 crystal has been estimated using magnetization vs field data obtained at various temperatures. A maximum magnetic entropy change (δSm max) of ∼-15.6J/kg/K has been observed at 22K with field along b axis and δSm max is ∼-11.2J/kg/K at 54K when field is parallel to ac plane, for a field change of 50 kOe. Occurrence of metamagnetic transition at temperatures below TN gives rise to a second peak at ∼22K in the temperature dependent isothermal magnetic entropy change that leads to the observed large magnetocaloric effect. © 2017 Elsevier B.V.