Giant room-temperature barocaloric effect at the electronic phase transition in Ni1-xFexS

Barocaloric (BC) materials are a type of promising solid-state refrigerant that can be used in future refrigerators. Besides the routine pressure-driven lattice entropy change, spin or polar degrees of freedom often make considerable contributions. Relatively, little attention has been paid to the electronic contribution. Here we demonstrate a sizable electronic entropy change under pressure in hexagonal Ni1-xFexS due to the remarkable modification of its electronic structure. Accordingly, the total entropy change reaches 52.8 J kg(-1)K(-1)under only 100 MPa, which places Ni1-xFexS among the giant BC materials. Again, because of the electronic contribution, the thermal conductivity of Ni1-xFexS is higher than the reported values of other giant BC materials, which can boost the cooling efficiency. Our work would inspire the study of the giant BC effect with good thermal conductance in a wide range of electronic phase transition materials.