ANNEALING AND PRESSURE EFFECTS ON STRUCTURAL AND FERROMAGNETIC TRANSITIONS OF LA0.85SR0.15MNO3 SINGLE-CRYSTALS

A detailed study of annealing and pressure effects on structural phase -transition temperature (T-s) and ferromagnetic transition temperature (T-c) was investigated for single crystal La0.85Sr0.15MnO3. T-s and T -c, respectively, decrease and increase with increasing pressure and a nnealing time, which indicated that the lattice distortion is relaxed and the double-exchange interaction is enhanced by annealing and press ure. Three states, orthorhombic phase state, orthorhombic and rhombohe dral phases coexisting state, and rhombohedral phase state, can be ind uced by controlling annealing time at high temperature and by hydrosta tic pressure. Tn the La0.85Sr0.15MnO3 compound, T-c was found to incre ase about 15 K when the orthorhombic phase transforms to the rhombohed ral phase.