Towards tailoring the magnetocaloric response in FeRh-based ternary compounds Available to Purchase

In this work, we demonstrate that the magnetocaloric response of FeRh-based compounds may be tailored for potential magnetic refrigeration applications by chemical modification of the FeRh lattice. Alloys of composition Fe(Rh_1−xA_x) or (Fe_1−xB_x)Rh (A = Cu, Pd; B = Ni; 0 < x < 0.06) were synthesized via arc-melting and subsequent annealing in vacuum at 1000 °C for 48 h. The magnetocaloric properties of the FeRh-based systems were determined using isothermal M(H) curves measured in the vicinity of the magnetostructural temperature (T_t). It is found that the FeRh working temperature range (δT_FWHM) may be chemically tuned over a wide temperature range, 100 K ≤ T ≤ 400 K. While elemental substitution consistently decreases the magnetic entropy change (ΔS_mag) of the FeRh-based ternary alloys from that of the parent FeRh compound (ΔS_mag,_FeRh ∼ 17 J/kg K; ΔS_{mag,FeRh-ternary =} 7–14 J/kg K at H_app = 2 T), the net refrigeration capacity (RC), defined as the amount of heat that can be transferred during one magnetic refrigeration cycle, of the modified systems is significantly higher (RC_FeRh ∼ 150 J/kg; RC_{FeRh-ternary =} 170–210 J/kg at H_app = 2 T). These results are attributed to stoichiometry-induced changes in the FeRh electronic band structure and beneficial broadening of the magnetostructural transition due to local chemical disorder.