Magnetocaloric effect in the rare earth intermetallic compounds RCoNi (R = Gd, Tb, Dy, and Ho)

Abstract

Magnetic and magnetocaloric properties of cubic Laves phase RCoNi (R = Gd, Tb, Dy, and Ho) compounds have been studied. The RCoNi (R = Gd, Tb, Dy, and Ho) compounds order ferromagnetically at ∼200 K, ∼113 K, ∼68 K, and ∼42 K (TC), respectively. Field dependent magnetization data of RCoNi at 5 K in fields up to 7 T reveal saturation behaviour with minimal hysteresis. Magnetocaloric effect in terms of isothermal magnetic entropy change has been calculated. Maximum isothermal magnetic entropy change values of ∼−7.2 J/kg/K, ∼−10.1 J/kg/K, ∼−15.5 J/kg/K, and ∼−19.6 J/kg/K are obtained for RCoNi (R = Gd, Tb, Dy, and Ho) compounds for 7 T field change close to TC. Substitution of 50 at. % Ni in Co-site of RCo2 has led to the reduction of TC of the parent compounds by nearly one-half, but broadened the magnetic entropy change vs T curve and hence improved the relative cooling power. The large magnetocaloric effect associated with RCoNi compounds makes them potential candidates for low temperature magnetic refrigeration applications.