Lattice dynamics and complete polarization analysis of Raman-active modes in LaInO$_3$

TL;DR

This paper combines polarization-resolved Raman spectroscopy and density functional theory to analyze and assign phonon modes in LaInO$_3$, providing detailed symmetry and vibrational information.

Contribution

It offers a comprehensive experimental and theoretical characterization of Raman-active phonons in LaInO$_3$, including symmetry assignment and tensor element extraction.

Findings

Most Raman-active phonons assigned to D$_{ m{2h}}$ irreducible representations

Raman tensor elements extracted from angular dependence data

Phonon dispersion and atomic displacement patterns computed and validated

Abstract

In this study, we present a comprehensive analysis of the Raman active phonon modes in orthorhombic LaInO$_3$ based on a combination of polarization-angle resolved Raman spectroscopy and density functional theory calculations. By using backscattering from multiple crystallographic surface orientations and employing a full symmetry analysis, we identify and assign most of the Raman-active $\Gamma$-point phonons to their irreducible representations of the D$_{\rm{2h}}$ point group. A multidimensional hyperspectral fitting procedure allows us to extract the relative Raman tensor elements from the angular dependence of the scattering intensities, even for strongly overlapping modes. First-principles calculations yield the phonon dispersion along high-symmetry directions, the phonon densities of states, and atomic displacement patterns, which are found to be in good agreement with the experimental mode frequencies.