Reproducible room temperature giant magnetocaloric effect in Fe–Rh

Abstract

We present the results of magnetocaloric effect (MCE) studies in polycrystalline Fe–Rh alloy over a temperature range of 250–345 K across the first order antiferromagnetic to ferromagnetic transition. By measuring the MCE under various thermomagnetic histories, contrary to the long held belief, we show here explicitly that the giant MCE in Fe–Rh near room temperature does not vanish after the first field cycle. In spite of the fact that the virgin magnetization curve is lost after the first field cycle near room temperature, reproducibility in the MCE under multiple field cycles can be achieved by properly choosing a combination of isothermal and adiabatic field variation cycles in the field-temperature phase space. This reproducible MCE leads to a large effective refrigerant capacity of 324.42 J kg−1, which is larger than that of the well-known magnetocaloric material Gd5Si2Ge2. This information could be important as Fe–Rh has the advantage of having a working temperature of around 300 K, which can be used for room temperature magnetic refrigeration.