Study on magnetic and optical properties of Mn-doped LiNbO3 by using the first principles

According to density functional theory of first-principles calculation theory, we study systematically the structure, magnetism, electronic and optical properties of Mn-doped LiNbO3. The enthalpies of formation of LiNbO3, when substituting Li and Nb with Mn, are -8.340 and -8.0062 eV/atom, respectively. This means that the LiNbO3 after substitution of Li with Mn is more stable than that of Nb with Mn. And the magnetic moments of LiNbO3 in the substitution of Li with Mn is higher than that in substitution of Nb with Mn. Results of the density of states calculation show that the magnetism comes from Mn atom, and its magnetic moments is 4.3 μB. The rest of the magnetic moments may come from the contribution of the O and Nb atoms, because of the interactions of Mn-3d orbit with the O-2p and Nb-4d orbits. Optical absorption spectra show an improved optical response in the visible range in LiNbO3 by substituting Li with Mn. Results of analysis of oxygen vacancy in LiNbO3 show that oxygen vacancy can improve the magnetic moments of Mn-doped LiNbO3 system.