The effect of pressure and magnetic field on the O-R structural phase transition in La1−xSrxMnO3 single crystals: the transition heat

We study the effect of pressure and a magnetic field on the temperature TS of the structural transition from orthorhombic to rhombohedral phase in La1−xSrxMnO3 single crystals. The temperature dependence of the phase volumes and the jumps in saturation magnetization (x=0.20 and 0.175) or magnetic susceptibility in paramagnetic state (x=0.15) have been measured and then the transition heats have been determined. In all crystals, the transition heat is very small (<0.6 kJ/mol). For given x, the heat derived from the TS−H curve is less than that derived from the TS−P curve, which is likely to indicate internal stresses in the crystals.