Enhanced magnetocaloric effect by the rare earth polarization due to the exchange with a transition metal. Study of GdCrO4

The zircon polymorph of GdCrO4 has a large magnetocaloric effect over a wide temperature range, with |ΔST| u003e 20 J/kg·K from 6 K to 34 K, for a magnetic field of 9 T. This unusual behaviour is very interesting on magnetic refrigeration applications, for liquefying H2 or natural gas. The mean-field approach explains that it is due to the weaker Gd-Cr magnetic exchange relative to the Cr-Cr one, while the Gd-Gd exchange is negligible. This possibility has not been sufficiently studied and opens an interesting strategy to design more efficient materials for magnetic refrigeration.