Magnetoelectric response of LiNiPO$_{4}$ from first-principles

The lithium orthophosphates LiMPO$_{4}$ (M = Mn, Fe, Co, Ni) have attracted large interest because of their potential use in cathode electrode for Li-ion batteries as well as their large magnetoelectric response and more recently because of the presence of ferrotoroidic domains in LiCoPO$_{4}$. Here we will discuss the response to a static magnetic field of LiNiPO$_{4}$ by means of first-principles calculations. This will allow us to extract the magnetic susceptibility as well as the magnetoelectric coefficients and to analyze their microscopic origin by decomposing the electronic and the ionic contributions. This last decomposition highlight the importance of the electronic contribution to the magnetoelectric response.