Neutron Diffraction, NMR and Magneto-Transport Properties in the Pr0.7Sr0.3MnO3 Perovskite Manganite

Abstract

Strontium substituted praseodymium manganite Pr0.7Sr0.3MnO3 powder was synthesized by a solid state reaction method at 1400 °C. Neutron diffraction analysis at room temperature and at 14.5 K shows that our sample belongs to the Pnma space group at both temperatures. At low temperature, the refinement gave 3.368μB for the Mn atoms and 0.273μB for the Pr atom, aligned ferromagnetically along the crystallographic y-axis. Magnetic measurements show that our sample exhibits a paramagnetic–ferromagnetic transition with decreasing temperature. The Curie temperature, TC, is found to be 250 K. Electrical studies show a semiconductor–metal transition at Tϱ = 260 K. This transition temperature is observed in the vicinity of the Curie temperature TC. Magneto-transport properties show a sharp drop in resistivity as a function of the magnetic applied field. Our sample displays a magnetoresistance effect at 8 T of about 80% in the vicinity of the Curie temperature TC. 55Mn NMR measurements at 4.2 K confirm the metallic behavior at low temperature. The time average resonance frequency indicates that electron hopping between Mn3+ and Mn4+ occurs over the whole crystal.