Phonon anomalies in lightly doped manganites La1−Sr MnO3 (x=0.09 and 0.11) near the CAF/FI phase boundary

Abstract We report a drastic change of the temperature dependence of the Mn–O stretching mode at the phase boundary between canted antiferromagnetic insulating (CAF) and ferromagnetic insulating (FI) of La 1− x Sr x MnO 3 . The observation of an unusual large softening by 18 cm −1 only in the FI phase is ascribed to a change of electronic state and orbital state through CAF/FI transition.