The ferromagnetic zircon-type phase of ${\mathrm{GdCrO}}_4$ presents high values for the magnetocaloric (MC) parameters. This compound has large isothermal entropy changes $\mathrm{\Delta }{S}_T$ under the magnetic field action in a wide temperature range, from 5 to 35 K, reaching a maximum $|\mathrm{\Delta }{S}_T|=29.0\pm 0.1\mathrm{J}/\mathrm{kg}\mathrm{K}$ at 22 K, for a field increment $\mathrm{\Delta }B=9$ T. It orders ferromagnetically at $T_{\mathrm{C}}=21.3\mathrm{K}$ via the Cr-Cr exchange interaction and shows a second transition at 4.8 K due to the ordering of the Gd sublattice. The large MC effect is enhanced by the polarization of the ${\mathrm{Gd}}^{3+}$ ions by the ${\mathrm{Cr}}^{5+}$ ones via a weaker Gd-Cr interaction. This effect is an interesting feature to be considered in the search for new compounds with a high MC effect in the range of liquid hydrogen or natural gas, regarding the liquefaction of gases by magnetization-demagnetization cycles. This paper contains experimental measurements of magnetization, heat capacity, and direct determinations of the MC effect. The magnetic contribution to the heat capacity $C_m$ has been obtained after subtracting the lattice component. Approximate values for the exchange constants $J_1$ (Cr-Cr) and $J_3$ (Gd-Cr) have been deduced from $C_m$.

• Received 12 November 2015
• Revised 27 January 2016

DOI:https://doi.org/10.1103/PhysRevB.93.064420