Switching of antiferromagnetic states in LiCoPO 4 as investigated via the magnetoelectric effect

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, which is needed to switch the AFM state, is proportional to the product of the $E$ and $H$ coercive fields ${(EH)}_{\mathrm{C}}$. We measured the field and temperature dependence of ${(EH)}_{\mathrm{C}}$ in ${\mathrm{LiCoPO}}_{4}$ for two different field configurations, and the data show the temperature variation of ${(EH)}_{\mathrm{C}}\ensuremath{\sim}{({T}_{\mathrm{N}}\ensuremath{-}T)}^{3/2}$ 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 ${(EH)}_{\mathrm{C}}$ follows a power-law frequency dependence and is well described in the framework of the Ishibashi-Orihara model, implying one-dimensional character of domain wall propagation.