We present a systematic study of the structure and lattice dynamics at room temperature, and the phonon behavior at low temperatures in orthorhombic Gd1−xYxMnO3 manganites, with 0 ≤ x ≤ 0.4, using powder x-ray diffraction and Raman scattering. A thorough analysis towards the correlation between both structural and Raman modes parameters was undertaken. The data obtained at room temperature reveal structural distortions arising from the Jahn-Teller distortion and octahedra tilting. The Jahn-Teller distortion is apparently x-independent, while an increase of Mn-O1-Mn bond angle of about 0.5{\deg} could be ascertain when x changes from 0 to 0.4. Spin-phonon coupling was evidenced from the Raman results. The temperature dependence of the B1g in-plane O2 stretching mode of the MnO6 octahedron has revealed either a positive or negative shift regarding the pure anharmonic temperature dependence of the phonon frequency, which strongly depends on the Y-concentration. The frequency renormalization is explained in terms of a competition between ferro and antiferromagnetic interactions. The ratio between the spin-phonon coupling constant and the effective magnetic exchange integral per spin was determined from the renormalized wave number of the in-plane O2 stretching mode, associated with the spin-spin correlation function.
@article{arxiv.1412.8350,
title = {Structural properties and spin-phonon coupling in orthorhombic Y-substituted GdMnO$_{3}$},
author = {R. Vilarinho and E. C. Queirós and A. Almeida and P. B. Tavares and J. Agostinho Moreira},
journal= {arXiv preprint arXiv:1412.8350},
year = {2014}
}