Design of new Mott multiferroics via complete charge transfer: promising candidates for bulk photovoltaics.

ABSTRACT: Optimal materials to induce bulk photovoltaic effects should lack inversion symmetry and have an optical gap matching the energies of visible radiation. Ferroelectric perovskite oxides such as BaTiO₃ and PbTiO₃ exhibit substantial polarization and stability, but have the disadvantage of excessively large band gaps. We use both density functional theory and dynamical mean field theory calculations to design a new class of Mott multiferroics-double perovskite oxides A ₂VFeO₆ (A?=?Ba, Pb, etc). While neither perovskite AVO₃ nor AFeO₃ is ferroelectric, in the double perovskite A ₂VFeO₆ a 'complete' charge transfer from V to Fe leads to a non-bulk-like charge configuration-an empty V-d shell and a half-filled Fe-d shell, giving rise to a polarization comparable to that of ferroelectric ATiO₃. Different from nonmagnetic ATiO₃, the new double perovskite oxides have an antiferromagnetic ground state and around room temperatures, are paramagnetic Mott insulators. Most importantly, the V d ⁰ state significantly reduces the band gap of A ₂VFeO₆, making it smaller than that of ATiO₃ and BiFeO₃ and rendering the new multiferroics a promising candidate to induce bulk photovoltaic effects.

SUBMITTER: Chen H 

PROVIDER: S-EPMC5522466 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature