Magnetic property under the pressure and electrical transport behavior under the magnetic field for the perovskite manganite La0.7Ca0.3MnO3

With respect to the magnetic properties under the pressure for the ferromagnetic metallic system La1-xCaxMnO3(0.18 <= x < 0.5), the main results concluded previously are as follows: the pressure suppresses the Jahn-Teller (J-T) distortion and promotes the Mn3+-O-Mn4+ double-exchange (DE), consequently increasing the magnetization and metallic conduction as well as the paramagnetic-ferromagnetic transition temperature (T-c). In this work, the magnetic properties under the pressure and the electrical transportation under the magnetic field for La0.7CaO3MnO3 polycrystalline were investigated. The pressure induces the antiferromagnetic coupling of the ferromagnetic clusters in the paramagnetic region above T-c, suppresses the J-T distortion around T-c and enhances the DE interaction, hence increasing T-c, and enhances the distortion of MnO6 octahedra in the ferromagnetic metallic region below T-c, resulting in the decrease of magnetization. The pressure induces the variation of anisotropy at the temperature far above T-c. These facts confirm that the effects of pressure depend on the ground-state properties of charge, spin and lattice. The resistivity measured under the different magnetic fields exhibits the magnetoresistance (MR) effects. MR appears a peak at 255 K, due to the enhanced DE interaction by the magnetic field and the increase in the kinetic energy of the eg electrons. (C) 2020 Elsevier B.V. All rights reserved.