Negative and conventional magnetocaloric effects of a MnRhAs single crystal

We report on the magnetic and magnetocaloric properties of a MnRhAs single crystal. The ternary arsenide exhibits a rather complex magnetic behaviour. A first order metamagnetic type transition from antiferromagnetic (AF(I)) to ferromagnetic ("F") states takes place at T-T similar to 158 K, and a second order transition from F to AF(II) states occurs at T-C similar to 196 K, the paramagnetic state occurring at T > T-N = 238 K. Magnetic entropy changes were calculated using, Maxwell relation, and Clausius-Clapeyron equation. Both approaches are compared and discussed. The AF(I)-F transition in MnRhAs gives rise to an interestingly high level of negative magnetocaloric effect. Under a field change 0-1 T, the maximum magnetic entropy variation is about 3 J/kg K. For sufficiently high enough magnetic fields, the magnetocaloric working temperature range below 158K can be covered. The F-AF(II) transition is accompanied by a relatively modest magnetocaloric effect (-2.3 J/kg K for 5 T at T-C = 196 K), but it improves the working temperature span as well as the magnetocaloric properties. A minimum estimated refrigerant capacity of about 900 J/kg can be provided by a MnRhAs single crystal compound. (C) 2014 AIP Publishing LLC.