Giant Magnetoelectric Effect in HoAl_3(BO_3)_4

TL;DR

This paper reports a giant magnetoelectric polarization in HoAl3(BO3)4, significantly surpassing previous multiferroic materials, driven by strong spin-lattice coupling and large ionic distortions under magnetic fields.

Contribution

It demonstrates an exceptionally large magnetoelectric effect in HoAl3(BO3)4, highlighting the role of strong spin-lattice coupling in enhancing magnetoelectric responses.

Findings

Magnetoelectric polarization reaches 3600 μC/m^2 at 70 kOe.

Strong spin-lattice coupling causes large ionic distortions.

Magnetostrictive effects are comparable to magnetoelectricity.

Abstract

A giant magnetoelectric polarization is found in HoAl$_3$(BO$_3$)$_4$. The polarization in transverse field geometry at 70 kOe reaches 3600 $\mu C/m^2$ which is significantly higher than reported values of linear magnetoelectric or even multiferroic compounds. The magnetostrictive effect is also measured and compared with the magnetoelectricity. The results show that spin-lattice coupling in HoAl$_3$(BO$_3$)$_4$ is extremely strong and that the magnetic field causes a large polar distortion of the ionic positions in the unit cell.