Giant reversible magnetocaloric effect in a multiferroic GdFeO3 single crystal

The magnetocaloric properties of single crystalline GdFeO₃ have been investigated in the temperature range 2-36 K by magnetization and heat-capacity measurements. Remarkably large and reversible magnetic entropy change, Δ S_m=-52.5 J/kg K, has been observed for a field change of 0-9 T. The adiabatic temperature change, Δ T_ad , is also found to be very large, 22 K, slightly above the antiferromagnetic ordering temperature (T_N^Gd=2.5 K) of the Gd^{3 +} moment, for a field change of 0-8 T. These magnetocaloric parameters remain large down to the lowest temperature measured and are significantly larger than that reported for the other members of rare-earth (R ) orthoferrites (R FeO₃ ) and several potential magnetic refrigerants in the same temperature range. Both Δ S_m and Δ T_ad are also quite large for a small field change. The large values of magnetocaloric parameters suggest that GdFeO₃ could be considered as a potential refrigerant in low-temperature magnetic refrigeration technology, such as liquefaction of hydrogen in the fuel industry. Moreover, GdFeO₃ has very low electrical conductivity and exhibits no thermal and field hysteresis in magnetization, fulfilling the necessary conditions for a good magnetic refrigerant.