Magnetoelectricity and Magnetostriction due to the Rare Earth Moment in TmAl$_3$(BO$_3$)$_4$

TL;DR

This study investigates the magnetic, magnetostrictive, and magnetoelectric properties of TmAl₃(BO₃)₄, revealing strong anisotropy, significant lattice effects, and a large magnetoelectric response driven by the rare earth magnetic moment.

Contribution

It demonstrates that the rare earth magnetic moment in TmAl₃(BO₃)₄ induces a substantial magnetoelectric effect linked to lattice contraction, advancing understanding of magnetoelectric interactions in rare-earth borates.

Findings

Large magnetoelectric polarization change up to 300 μC/m² at 70 kOe

Strong anisotropy with the c-axis as the hard magnetic axis

Magnetostriction correlates with magnetoelectric polarization

Abstract

The magnetic properties, the magnetostriction, and the magnetoelectric effect in the d-electron free rare-earth aluminum borate TmAl$_3$(BO$_3$)$_4$ are investigated between room temperature and 2 K. The magnetic susceptibility reveals a strong anisotropy with the hexagonal c-axis as the hard magnetic axis. Magnetostriction measurements show a large effect of an in-plane field reducing both, the a- and c-axis lattice parameters. The magnetoelectric polarization change in a- and c-directions reaches up to 300 $\mu$C/m$^2$ at 70 kOe with the field applied along the a-axis. The magnetoelectric polarization is proportional to the lattice contraction in magnetic field. The results of this investigation prove the existence of a significant coupling between the rare earth magnetic moment and the lattice in $R$Al$_3$(BO$_3$)$_4$ compounds ($R$ = rare earth). They further show that the rare earth moment itself will generate a large magnetoelectric effect which makes it easier to study and to understand the origin of the magnetoelectric interaction in this class of materials.