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 (T_C ～336 K) with a narrow refrigeration temperature span, which limits the refrigeration application at room temperature. Here we show that the T_C 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.