Small influence of magnetic ordering on lattice dynamics in TaFe$_{1.25}$Te$_3$

TL;DR

This study investigates how magnetic ordering influences lattice vibrations in TaFe$_{1.25}$Te$_3$, finding minimal impact and highlighting the dominance of lattice anharmonicity in phonon behavior.

Contribution

The paper provides experimental Raman spectra and lattice dynamics calculations showing weak effects of magnetic ordering on lattice vibrations in TaFe$_{1.25}$Te$_3$.

Findings

Raman active modes are clearly observed and assigned.

Temperature dependence of linewidths is mainly due to anharmonicity.

Minimal changes in spectra near magnetic transition suggest weak electron-phonon coupling.

Abstract

Raman scattering spectra of zigzag spin chain TaFe$_{1.25}$Te$_3$ single crystal are presented in a temperature range from 80 to 300 K. Nine Raman active modes of $A_g$ and $B_g$ symmetry are clearly observed and assigned by probing different scattering channels, which is confirmed by lattice dynamics calculations. Temperature dependence of the Raman modes linewidth is mainly governed by the lattice anharmonicity. The only deviation from the conventional behavior is observed for $A_g$ symmetry modes in a vicinity of the magnetic phase transition at $T_N \approx 200$ K. This implies that the electron-phonon interaction weakly changes with temperature and magnetic ordering, whereas small changes in the spectra near the critical temperature can be ascribed to spin fluctuations.