Effect of Structural and Magnetic Transitions in La1-xMxMnO3 [M=Sr,CA] Single Crystals in Raman Scattering

Published

July 1, 1998

Author(s)

V B. Podobedov, A Weber, D B. Romero, Joseph P. Rice, H D. Drew

Abstract

Polarized Raman spectra of undoped and doped La1-xMxMnO3 single crystals have been studied in the temperature range from 5 K to 423 K [M=Sr, Ca]. The spectral intensity is mainly related to scattering by optical phonons at q difference of} O [for x3-0] and the density of vibrational states for x > 0.1. The analyses of the vibrational spectra were carried out within the orthorthombic, rhombohedral and cubic symmetries of the La1-xMxMnO3 systems. The Pnma lattice structure of undoped laMnO3 crystal distorted by the static Jahn-Teller effect belongs to the orthorhombic D2h16 space group. Most of the predicted Raman active nodes of Ag and Bg symmetries were detected in the frequency range 30-700 cm-1. Raman spectra of the doped La1 xMxMnO3 crystals have weakly-resolved features and intensities comparable to those of the second-order spectra in cubic media. A simple dependence of the external mode frequency shifts of Raman modes with temperature were observed. The most intense B1g mode in LaMnO3 crystal has an abrupt frequency shift near Tc = 140 K, which corresponds to a paramagnetic to canted- antiferromagnetic phase transition.

Citation

Physical Review B

Volume

58

Issue

No. 1

Pub Type

Journals

Keywords

phonons, LaMnO3, Raman scattering, single crystal

Citation

Podobedov, V. , Weber, A. , Romero, D. , Rice, J. and Drew, H. (1998), Effect of Structural and Magnetic Transitions in La_1-xM_xMnO₃ [M=Sr,CA] Single Crystals in Raman Scattering, Physical Review B (Accessed April 25, 2024)