Jahn-Teller transition in La_1−xSr_xMnO₃ in the low-doping region(0<x<∼0.1)

Abstract

We have investigated the Jahn-Teller transition in La_1−xSr_xMnO₃ by high-temperature powder neutron diffraction in the low-doping region ( 0<x<∼0.1) . The Jahn-Teller transition temperature which is about T_JT ≈ 750 K for stoichiometric LaMnO₃ is drastically reduced on doping with Sr, becoming T_JT ≈ 475 K for x = 0.10. The previously identified metrically cubic orthorhombic O phase (Pmnb) for x = 0 becomes clearly (also metrically) orthorhombic for small doping x = 0.05 and remains so in the doping range investigated. The Jahn-Teller transition is accompanied only by the partial reduction of the distortion of the MnO₆ octahedra. From the distortion of the MnO₆ octahedra we have determined the orbital mixing coefficients.