Large magnetocaloric effect with a wide temperature range in Gd5Si4

Gd5Si4 magnets have attracted much attention due to their many appealing properties such as strong ferromagnetism, magnetovolume effect, and large reversal magnetocaloric effect (MCE). However, Gd5Si4 exhibits a relatively high Curie temperature (TC ∼336 K) with a narrow refrigeration temperature span, which limits the refrigeration application at room temperature. Here we show that the TC of Gd5Si4 can be reduced to 330 K and the phase transition temperature range can be effectively expanded by applying a high pressure of 6 GPa to the sample during heat treatment. In addition, the room-temperature magnetic entropy changes are improved and the refrigeration temperature span also becomes wider, which leads to an enhanced relative cooling power (RCP) of 748 Jkg-1 under a magnetic field change of 5 T. These unique features indicate that the Gd5Si4 compound prepared under high pressure can serve as a magnetic refrigerant in a wide temperature range covering room temperature.