Hydrostatic pressure effect on the spin reorientation transition of ferromagnetic Sm_(0.7-x)La_xSr_(0.3)MnO_3 (x = 0, 0.1) polycrystals

摘要

The hydrostatic pressure effect on the resistivity and magnetization of the narrow band gap manganite Sm_(0.7-x)La_xSr_(0.3)MnO_3 (x = 0, 0.1) systems has been investigated. At ambient pressure measurements, the parent compound Sm_(0.7)Sr_(0.3)MnO_3 showed a ferromagnetic-insulating nature, whereas the 10% La-doped compound Sm_(0.6)La_(0.1)Sr_(0.3)MnO_3 showed a ferromagnetic-metallic nature. Furthermore, both samples showed a spin-reorientation transition (T_(SR)) 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 Sm_(0.7)Sr_(0.3)MnO_3 under pressure did not show an appreciable change in the Curie temperature, but enhanced T_(SR), whereas an insulator-metallic transition was observed during resistivity measurements under pressure. On the other hand, for Sm_(0.6)La_(0.1)Sr_(0.3)MnO_3, T_c increased and T_(SR) 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 Sm_(0.7)Sr_(0.3)MnO_3, but increased it in SmO_6La_(0.1)Sr_(0.3)MnO_3. 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.