Dielectric susceptibility of magnetoelectric thin films with vortex-antivortex dipole pairs

TL;DR

This paper models a quasi-2D magnetoelectric system using an XY model to analyze how vortex-antivortex pairs influence dielectric susceptibility, revealing divergence near the BKT transition temperature.

Contribution

It introduces a model linking vortex-antivortex pairs to dielectric response in magnetoelectric thin films, highlighting divergence at the BKT transition.

Findings

Dielectric susceptibility diverges at T approaching T_BKT.

Vortex-antivortex pairs contribute significantly to dielectric properties.

The model connects topological defects to dielectric behavior in thin films.

Abstract

We consider model of quasi-2D magnetoelectric material as XY model for spin system on a lattice with local multiferroic-like interaction of spin and electric polarization vectors. We calculate the contribution of magnetic (spin) vortex-antivortex pairs (which form electric dipoles) to the dielectric susceptibility of the system. We show that in approximation of non-interacting pairs at $T \rightarrow T_{BKT}$ (Berezinskii-Kosterlitz-Thouless temperature) dielectric susceptibility diverges.