Impurity effects in multiferroic compounds

TL;DR

This paper studies how impurities affect multiferroic materials, showing that increasing impurity strength dampens spin oscillations and suppresses electric polarization, thus harming multiferroic properties.

Contribution

It introduces an equation of motion approach modeling impurities as two-level systems, revealing their detrimental impact on multiferroic behavior.

Findings

Weak impurities do not affect polarization

Strong impurities damp spin oscillations

Impurities suppress multiferroic polarization

Abstract

We investigate the effect of impurities in multiferroic materials using an equation of motion approach for the spin dynamics of the host multiferroic compound. We model the impurities as a two-level system and focus on the regime where the impurity spins relax slowly. When the impurity strength is weak the host spins oscillate with no decay and the electric polarization is not affected. However as the impurity strength is increased the host spin components get damped and the electrion polarization is suppressed. Since polarization in multiferroic materials is driven by magnetic ordering we conclude that the presence of impurities is detrimental to multiferroicity.