Room temperature giant magnetocaloric effect in Pd doped FeRh and the effect of martensitic transition

Abstract

FeRh 0.8 Pd 0.2 is known to exhibit near room-temperature first-order antiferromagnetic (AF)–ferromagnetic (FM) transition, typical of chemically ordered FeRh system. In addition, it is also reported to show martensitic transition at a lower temperature. In this work, the effect of sample history on transition temperature (Tt) and the magnetocaloric effect (MCE) have been studied. The experimentally determined MCE parameters across FM to AF transition induced either by isothermal magnetic field sweep or by temperature sweep showed a large isothermal change in entropy around room temperature, i.e., 14 J/kg K for 50 kOe magnetic field change, whereas MCE corresponding to AF–FM transition depends on cooling history. Our study shows that in the presence of martensite phase, the peak value of MCE is shifted to higher temperatures but with significantly reduced magnitude.