Physical Properties of Oxygen Composition Controlled La{sub}(1-x)Sr{sub}xMnO{sub}y, Single Crystals

摘要

We have investigated the effect of high-temperature post-annealing and control of excess oxygen for La{sub}(1-x)Sr{sub}xMnO{sub}y, (0.05≤x≤0.2) single crystals. Thin plate-like single crystals prepared by careful cutting and polishing enabled the control of excess oxygen for the single crystals by post-annealing for relatively short times at various temperatures. Post-annealed crystals with y ～3.00 exhibited higher T{sub}c than as-grown crystals due to a homogenization of cation and oxygen compositions and reduction of local lattice strains. With an increase of y, T{sub}c systematically increased for all Sr compositions. Competition between an increase of mean valence of manganese and a generation of cation vacancies determines the T{sub}c of La{sub}(1-x)Sr{sub}xMnO{sub}y crystals.