Multiple Magnetoelectric Plateaux in Polar Magnet Fe$_2$Mo$_3$O$_8$

TL;DR

This study investigates the multistep magnetoelectric effects in Fe$_2$Mo$_3$O$_8$, revealing complex magnetic and electric behaviors under high magnetic fields and proposing a model to explain these phenomena.

Contribution

It introduces a combined triangular-lattice antiferromagnetic model with strong Ising anisotropy to explain multistep magnetoelectric effects in Fe$_2$Mo$_3$O$_8$.

Findings

Multistep magnetization process observed below 65 T.

Electric polarization shows similar multistep behavior with a 1.2 μC/cm² change.

The exchange striction mechanism accounts for the magnetoelectric response.

Abstract

The magnetization and electric polarization of a polar antiferromagnet Fe$_2$Mo$_3$O$_8$ are studied up to 66 T for spin-saturation magnetic fields applied along the polar axis. The magnetization process at 1.4 K exhibited multistep structures below the saturation field of 65 T. The electric polarization along the polar axis exhibits a similar multistep behavior with a total change of 1.2 $\rm{\mu}C/cm^{2}$. A combined triangular-lattice antiferromagnetic model with strong Ising-type spin anisotropy reproduces this multistep magnetoelectric (ME) effect. The exchange striction mechanism explains the remarkable ME response in the two sub-lattice type-I multiferroic materials. These results and interpretation demonstrate a method for realizing multistage magnetoelectric effects in hybrid spin systems.