Magnetodielectric coupling in a triangular Ising lattice

TL;DR

This study investigates the magnetodielectric effect in a geometrically frustrated triangular Ising cobaltite, demonstrating coupling between magnetic and dielectric properties below 25K and modeling this interaction with Landau theory.

Contribution

It provides experimental evidence of magnetodielectric coupling in Ca3Co2O6 and introduces a theoretical model based on Landau formalism to describe this phenomenon.

Findings

Magnetodielectric effect observed below 25K in Ca3Co2O6

Peak in dielectric constant at magnetic transition

Model explains coupling via two order parameters

Abstract

Dielectric constant measurement under magnetic field is an efficient technique to study the coupling between charges and spins in insulating materials. For magnetic oxides, the geometric frustration is known to be a key ingredient to observe such a coupling. Measurements for the triangular Ising-like cobaltite Ca3Co2O6 have been made. Single crystals of Ca3Co2O6 are found to exhibit a magnetodielectric effect below TN=25K with a peak in the e(H) curve at the ferri to ferromagnetic transition. This relation between e and magnetization has been modelized by using two order parameters in an energy expansion derived from the Landau formalism and the fluctuation-dissipation theorem. This result emphasizes the great potential of insulating transition metal oxides for the search of magnetodielectric effect.