Hydrostatic pressure effect on the spin reorientation transition of ferromagnetic Sm0.7−xLaxSr0.3MnO3 (x = 0, 0.1) polycrystals

The hydrostatic pressure effect on the resistivity and magnetization of the narrow band gap manganite Sm0.7−xLaxSr0.3MnO3 (x = 0, 0.1) systems has been investigated. At ambient pressure measurements, the parent compound Sm0.7Sr0.3MnO3 showed a ferromagnetic-insulating nature, whereas the 10% La-doped compound Sm0.6La0.1Sr0.3MnO3 showed a ferromagnetic-metallic nature. Furthermore, both samples showed a spin-reorientation transition (TSR) below Curie temperature, which originated from the Mn sublattice and was supported by an antiferromagnetic Sm(4f)-Mn(3d) interaction. Both samples exhibited a normal and inverse magnetocaloric effect as a result of these two different magnetic transitions. Magnetization measurements on Sm0.7Sr0.3MnO3 under pressure did not show an appreciable change in the Curie temperature, but enhanced TSR, whereas an insulator-metallic transition was observed during resistivity measurements under pressure. On the other hand, for Sm0.6La0.1Sr0.3MnO3, TC increased and TSR reduced upon the application of pressure. The metallic nature which is observed at ambient pressure resistivity measurement was further enhanced with 97% of piezoresistance. The pressure did not change the normal magnetocaloric effect of Sm0.7Sr0.3MnO3, but increased it in Sm0.6La0.1Sr0.3MnO3. However, there was not much change in the inverse magnetocaloric effect of both compounds. These studies were analyzed based on the pressure effect on the activation energy and scattering interaction factors.