Electronic, magnetic and multiferroic properties of magnetoelectric NiTiO3

The structural, electronic, magnetic, and ferroelectric properties of NiTiO3 are predicted through ab initio calculations based on the density functional theory (DFT). The theoretical structure parameters matched well with those obtained experimentally. The electronic structure results show that the antiferromagnetic (AFM) phase of LiNbO3 (LN)-type NiTiO3 has a direct band gap of 2.16 eV. The calculated local magnetic moment of Ni ion is 1.61μB. The calculated Born effective charges (BECs, denoted by tensor Z*) show that the Z* of Ti and O atoms are significantly and anomalously large. Interestingly, ferroelectric spontaneous polarization is predicted to be along [1 1 1] direction with a large magnitude of 97 μC/cm2. B-site Ti ions in 3d0 state dominate ferroelectric polarization of multiferroic NiTiO3, whereas A-site Ni ions having partially filled eg orbitals are considered to contribute to the antiferromagnetic properties of NiTiO3. Furthermore, the current study also found that the polar lattice distortion can induce weak ferromagnetism.