The magnetoelectric effect due to a semispherical capacitor surrounded by a spherical topologically insulating shell

TL;DR

This paper investigates the magnetoelectric effect in a spherical capacitor setup with a topologically insulating shell, calculating magnetic fields that could be detected with current sensitive magnetometers.

Contribution

It provides a theoretical analysis of the magnetoelectric effect in a novel spherical capacitor configuration with topological insulator surroundings.

Findings

Magnetic fields produced are within detection limits of NV-center magnetometers.

The setup enhances the measurable magnetoelectric response.

Theoretical framework uses modified Maxwell equations with scalar potentials.

Abstract

We consider the magnetoelectric effect produced by a capacitor formed by two semispherical perfectly conducting plates subjected to a potential difference and surrounded by a spherical shell of a topologically insulating material. The modified Maxwell equations are solved in terms of coupled electric and magnetic scalar potentials using spherical coordinates and in the approximation where the effective magnetoelectric coupling is of the order of the fine structure constant. The emphasis is placed in the calculation of the magnetic field for several relevant configurations designed to enhance the possibility of measuring this field. The magnitudes we obtain fall within the sensitivities of magnetometers based upon nitrogen-vacancy centers in diamond as well as of devices using scanning SQUID magnetometry.