Large barocaloric effect in intermetallic La1.2Ce0.8Fe11Si2H1.86 materials driven by low pressure

Barocaloric materials are particularly promising for green and efficient solid-state cooling technology because of their great potential in terms of cooling performance. However, intermetallic materials with outstanding barocaloric effects under low hydrostatic pressure are especially lacking, which has severely delayed the development of barocaloric refrigeration. Here, in a rare-earth intermetallic La-Ce-Fe-Si-H, we achieve a giant specific barocaloric temperature change of 8 K per kbar according to direct measurements of the adiabatic temperature change Delta T-BCE under hydrostatic pressure, which is confirmed by a phenomenological transition simulation. This barocaloric strength is significantly better than those in previously reported phase-transitioned alloys. By using a cutting-edge in situ neutron diffraction technique operating under simultaneously varying temperature, magnetic field, and hydrostatic pressure, we reveal that the large isotropic transition volume change in La-Ce-Fe-Si-H plays a crucial role in the giant barocaloric effect. Additionally, we employ Landau expansion theory to demonstrate that the high sensitivity of the transition temperature to the applied pressure produces the sizable Delta T-BCE in the itinerant electron metamagnetic transition alloys. Our results provide insight into the development of high-performance barocaloric materials and related cooling systems.