Probing the effect of magnetic field on charge order in the quasi-two-dimensional Mott insulator κ−(ET)2Hg(SCN)2Cl

Abstract

Molecular-based quasi-two-dimensional charge-ordered Mott insulators can possess both spin $S=1/2$ and an electric dipole degree of freedom residing on each ${(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}$ lattice site. There exists a theoretical proposal for a magnetoelectric effect in such a material, which can manifest itself as a sensitivity of charge distribution on ${(\mathrm{BEDT}\text{\ensuremath{-}}\mathrm{TTF})}_{2}$ dimers to the magnetic field. In this work, we used Raman scattering spectroscopy in the magnetic field up to 31 T applied perpendicular to the two-dimensional triangular lattice planes to probe a magnetoelectric effect in $\ensuremath{\kappa}\text{\ensuremath{-}}{(\mathrm{ET})}_{2}\mathrm{Hg}{(\mathrm{SCN})}_{2}\mathrm{Cl}$. This is a model compound, which shows charge order and antiferromagnetic correlations at temperatures below 30 K. We discuss possible reasons for the absence of an observable magnetoelectric effect in the probed temperature and magnetic field ranges.