A new cooling process driven by charge transfer mechanism: Application to YbInCu4

Abstract In this work, we theoretically discuss the entropy change and the barocaloric effect in Y b I n C u 4 , which undergoes at ambient pressure a valence transition around 42  K . In order to carry out the calculations, we use a microscopic model consisting in a narrow band of 4 f electrons coupled with a wide band of conduction electrons. Our calculations show that the charge transfer between the bands, which explains the experimentally observed valence transition, produces large entropy change and consequently large caloric effect around the valence transition temperature. This new type of cooling process induced by the charge transfer mechanism opens up a horizon in this area of research and can be very important for solid state refrigerators technology.