Inverse magnetocaloric effect in ferromagnetic Sm0.6-xLaxSr0.4MnO3 due to 4f-3d exchange interaction

We report magnetic and magnetocaloric properties of Sm0.6-xLaxSr0.4MnO3 (x = 0-0.6). A rapid increase around TC and an anomalous peak at a temperature T*<<TC occur in magnetization which lead to normal and inverse magnetocaloric effects (MCE), respectively. While TC increases with increasing x (TC=118 K for x=0 and TC=363 K for x=0.6), T* increases from 30 K (x=0) to 120 K (x=0.4) and then decreases to 105 K (x=0.5). The \DeltaSm reaches +1.07 Jkg-1K-1 at 10 K and -4 Jkg-1K-1 around TC in x=0.4 for \Delta H=5T. The inverse MCE is attributed to antiferromagnetic coupling between Sm-4f and Mn-3d magnetic moments.