Structural and magnetic phase diagrams of La1-xSrxMnO3 and Pr1-ySryMnO3 -: art. no. 094431

The nuclear and magnetic structures and properties of La1-xSrxMnO3 with 0.45less than or equal toxless than or equal to1 and Pr1-ySryMnO3 (0.58less than or equal toyless than or equal to1) were investigated using neutron powder diffraction, resistivity and magnetic measurements. In this paper, we present the full magnetic and structural phase diagram for La1-xSrxMnO3 and a partial phase diagram for Pr1-ySryMnO3. At low temperatures, we observe a series of structural phase transitions evolving as a function of increasing x as follows: orthorhombic Pbnm-->rhombohedral R (3) over barc-->orthorhombic Fmmm-->tetragonal I4/mcm-->cubic Pm (3) over barm. At higher temperatures, the orthorhombic Fmmm structural region disappears. We also identify four magnetic states (FM, A, C, and G type) evolving as a function of increasing x. The magnetic and nuclear structural transitions coincide for samples with 0.8less than or equal toxless than or equal to0.95. In the 0.5less than or equal toxless than or equal to0.9 region, resistivity and magnetic measurements show a substantial hysteresis near T-N. This hysteresis of a few K is indicative of a first order antiferromagnetic transition in good agreement with the neutron diffraction results. Our data also suggest the existence of a strong competition between the ferromagnetic and A-type states for xsimilar to0.5, and between the C- and G-type states for xsimilar to0.95. A similar behavior is observed for Pr1-ySryMnO3.