Effect of Fe substitution on magnetocaloric effect in borocarbide superconductor Dy(Ni1-xFex)2B2C

The magnetic properties and magnetocaloric effect (MCE) in antiferromagnetic superconductor Dy(Ni1-xFex)2B2C (x = 0, 0.1, and 0.2) has been studied. The magnetic transition temperature TM as well as the temperature at the maximum of magnetic entropy change (-ΔSMmax) slightly shift to low temperature with increasing x. An inverse MCE was observed, which is attributed to the nature of antiferromagnetic state under low magnetic field and at low temperatures for the present Dy(Ni1-xFex)2B2C compounds. A normal large MCE was observed under higher magnetic field changes, which is related to a field-induced first order meatmagnetic transition from antiferromagnetic to ferromagnetic state. Under a magnetic field change of 7 T, the values of -ΔSMmax reach 22.1, 16.6, and 14.8 J Kg-1 K-1 for x = 0, 0.1, and 0.2, respectively. The corresponding values of relative cooling power are 464, 332 and 295 J/kg. The observed large magnetic entropy is related to a field-induced first order metamagnetic transition from antiferromagnetic to ferromagnetic state.