Lattice vibrational modes in changchengite from Raman spectroscopy and first principles electronic structure

TL;DR

This study combines Raman spectroscopy and first-principles calculations to analyze lattice vibrational modes in changchengite, revealing good agreement between experiment and theory and insights into electronic properties related to spin-orbit effects.

Contribution

It provides the first combined experimental and theoretical analysis of phonon modes in changchengite, highlighting the role of spin-orbit coupling and lattice parameters.

Findings

All predicted Raman modes are experimentally observed.

Good agreement between experimental and theoretical phonon wavenumbers when using experimental lattice parameters.

Spin-orbit coupling has minimal impact on phonon wavenumbers.

Abstract

We measured room-temperature phonon Raman spectra of changchengite (IrBiS) and compared the experimental phonon wavenumbers to the theoretical ones obtained by means of the \emph{ab initio} density-functional-theory calculations in the presence and absence of the spin-orbit coupling effects. Combining two different excitation photon energies all the symmetry predicted Raman modes are experimentally observed. The electronic properties of IrBiS are found to be similar to the recently studied isostructural compound IrBiSe showing a large Dresselhaus spin-orbit valence band splitting. A good agreement between the experimental and theoretically predicted Raman phonon wavenumbers is found only when the lattice parameter is constrained to the experimental value. The inclusion of the spin orbit coupling does not significantly affect the phonon wavenumbers.