First-order valence transition and barocaloric effect in EuNi2(Si1−xGex)2

Abstract We observed in EuNi2(Si0.15Ge0.85)2 a very sharp, first-order valence transition from an Eu2+ to an Eu3+ state at around Tv≈42 K. The transition presents a large thermal hysteresis of 10 K. The huge entropy change associated with the valence transition gives rise to a barocaloric effect, which may find use in magnetic cooling by the application of pressure.