Magnetoelectric effect in organic molecular solids.

Makoto Naka,Sumio Ishihara

doi:10.1038/srep20781

Abstract

The Magnetoelectric (ME) effect in solids is a prominent cross correlation phenomenon, in which the electric field (E) controls the magnetization (M) and the magnetic field (H) controls the electric polarization (P). A rich variety of ME effects and their potential in practical applications have been investigated so far within the transition-metal compounds. Here, we report a possible way to realize the ME effect in organic molecular solids, in which two molecules build a dimer unit aligned on a lattice site. The linear ME effect is predicted in a long-range ordered state of spins and electric dipoles, as well as in a disordered state. One key of the ME effect is a hidden ferroic order of the spin-charge composite object. We provide a new guiding principle of the ME effect in materials without transition-metal elements, which may lead to flexible and lightweight multifunctional materials.

Highlights

The Magnetoelectric (ME) effect in solids is a prominent cross correlation phenomenon, in which the electric field (E) controls the magnetization (M) and the magnetic field (H) controls the electric polarization (P)
Interest in the ME effect has been recently revived[6,7]. This is ascribed to the several recent developments: i) large non-linear ME effects discovered in TbMnO3 and other multiferroic materials with spin frustration[8,9,10,11,12,13,14], ii) significant development of synthesis techniques for artificial ME composites, e.g. BaTiO3/CoFe2O415,16, and iii) a new theoretical framework for the ME polarizability, which is related to the axion electrodynamics, by which the ME tensor is evaluated qualitatively from first principles[17,18]
Numerical calculations in a two-dimensional lattice modeling the κ-(BEDT-TTF) type organic molecular solids demonstrate that the linear ME effect emerges in a long-range ordered state of spins and electric dipoles owing to the electronic degree of freedom inside the molecular dimers

Summary

Introduction

The Magnetoelectric (ME) effect in solids is a prominent cross correlation phenomenon, in which the electric field (E) controls the magnetization (M) and the magnetic field (H) controls the electric polarization (P). Numerical calculations in a two-dimensional lattice modeling the κ-(BEDT-TTF) type organic molecular solids demonstrate that the linear ME effect emerges in a long-range ordered state of spins and electric dipoles owing to the electronic degree of freedom inside the molecular dimers.

Results

Conclusion