Lattice dynamics and spontaneous magnetodielectric effect in ilmenite CoTiO$_3$

TL;DR

This study investigates the lattice vibrations and magnetodielectric effects in CoTiO$_3$, revealing phonon behaviors and dielectric changes linked to antiferromagnetic ordering, supported by experimental spectroscopy and DFT calculations.

Contribution

It provides a comprehensive analysis of phonon modes and their coupling with magnetic order in CoTiO$_3$, highlighting the spontaneous magnetodielectric effect and establishing a basis for future spin-phonon interaction studies.

Findings

Identification of all infrared and Raman active phonons.

Observation of dielectric permittivity changes below the Néel temperature.

Evidence of spontaneous magnetodielectric effect in CoTiO$_3$.

Abstract

Ilmenite-type crystals find a variety of technological applications due to their intriguing physical properties. We present the results of the lattice dynamics studies of honeycomb antiferromagnetic ilmenite CoTiO$_3$ single crystal by the complementary polarized infrared, Raman, and dielectric spectroscopic techniques that are supplemented by the DFT calculations. The frequencies and symmetries of all predicted infrared and Raman active phonons were uniquely identified. Furthermore, it was found that the dielectric permittivity demonstrates distinct changes below antiferromagnetic ordering temperature in zero magnetic field due to spontaneous magnetodielectric effect. Our results establish the reliable basis for further investigation of the coupling of phonons with spins, magnetic excitations and other physical phenomena of this promising material.