Switching of antiferromagnetic states in LiCoPO$_4$ as investigated via the magnetoelectric effect

TL;DR

This study investigates the switching behavior of antiferromagnetic states in LiCoPO$_4$ using the magnetoelectric effect, combining experimental measurements with a phenomenological model to understand the energy barriers and domain dynamics involved.

Contribution

The paper presents a combined experimental and theoretical analysis of AFM state switching in LiCoPO$_4$, revealing the temperature dependence of the energy barrier and domain wall dynamics.

Findings

The energy barrier for switching scales with (T_N - T)^{3/2}.

The coercive field exhibits a power-law frequency dependence.

Domain wall propagation is effectively one-dimensional.

Abstract

The linear magnetoelectric (ME) effect allows for the selection or switching between two antiferromagnetic (AFM) states via the application of large electric ($E$) and magnetic ($H$) fields. Once an AFM state is selected, it is preserved by an energy barrier, even when the fields are removed. Using a simple phenomenological model, we find that this energy barrier, needed to switch the AFM state, is proportional to the product of the $E$ and $H$ coercive fields $(EH)_{\rm C}$. We measured the field and temperature dependence of $(EH)_{\rm C}$ in LiCoPO$_4$ for two different field configurations, and the data show the temperature variation of $(EH)_{\rm C}\sim(T_{\rm N}-T)^{3/2}$ in good agreement with the model. We also investigated the dynamics of the AFM domain switching using pulsed $E$-field measurements. It was found that the coercive field $(EH)_{\rm C}$ follows a power-law frequency dependence and is well described in the framework of Ishibashi-Orihara model, implying 1-dimensional character of domain wall propagation.