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, Delta S-m = -52.5 J/kg K, has been observed for a field change of 0-9 T. The adiabatic temperature change, Delta 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 Gd3+ 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 (RFeO3) and several potential magnetic refrigerants in the same temperature range. Both Delta S-m and Delta 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.