First principles calculation on the magnetic, optical properties and oxygen vacancy effect of CexY3-xFe5O12

We report a first principles study on the magnetic and optical properties of Ce substituted yttrium iron garnet (CexY3-xFe5O12) (Ce:YIG) (x = 0.125, 0.25, 0.5, and 1.0). Using density functional theory with Hubbard-U corrections, we demonstrate that Ce3+-Fe3+(tetrahedral) charge transfer is the dominating mechanism of enhanced near infrared absorption in Ce: YIG. In particular, oxygen vacancies are found to be able to stabilize Ce3+ from converting to Ce4+, at the same time reduce two neighboring Fe3+ to Fe2+ which occupy both the octahedral and tetrahedral sites. The formation enthalpy of Ce4+-Fe2+ state is strongly dependent on the distance from the Ce ion to the oxygen vacancy, which is closely related to the local lattice distortion around the Ce ion. This result provides theoretical insight for developing high figure of merit magneto-optical materials for nonreciprocal photonic applications. (C) 2015 AIP Publishing LLC.