Electronic, magnetic and optical properties of the charge-disproportionated YNiO3 compound calculated using the GGA+U method.

ABSTRACT

The electronic, magnetic and optical properties of YNiO3 were studied using the GGA+U method. This compound presents charge disproportionation with two nonequivalent Ni ion sites, namely, Ni1 with Ni(3-δ)+ and Ni2 with Ni(3+δ)+. A band-structure calculation was performed for the observed P21/n monoclinic phase; a 2 × 1 × 2 supercell with 80 atoms was used to reproduce the observed magnetic ordering. The density of states (DOS) calculation clearly showed the bonding differences between the Ni1 and the Ni2 sites; the Ni1 site has a more ionic character, whereas the Ni2 site presents a more covalent character. The band-structure results correspond to an insulator phase with a band gap of about 0.5 eV. The magnetic ordering is antiferromagnetic and the magnetic moments are about 1.24 µ B for Ni1 and around 0.00 µ B for Ni2. The calculated magnetic ordering results are in good agreement with neutron diffraction results. The calculated optical conductivity is similar to previous experimental data.