Prediction of a metal–insulator transition and a two-dimensional electron gas in orthoferrite LaTiO3/tetragonal BiFeO3 heterostructures

Abstract

Using first-principles calculations, we investigate the electronic and magnetic properties of orthoferrite LaTiO₃/tetragonal BiFeO₃ superlattices with different terminations. The interfacial electronic reconstruction along with formed chemical bonds transforms LaTiO₃ into a metal by means of the Anderson and Mott transition. In particular, a two-dimensional electron gas appears at interfacial regions located in LaTiO₃ of model LaO–BiO and BiFeO₃ of model TiO₂–BiO due to the d–p, d–d electron interactions and ferroelectric polarization. Moreover, the Fe and Ti magnetic moments are sensitive to the interfacial geometry and hybridization, and a 19% spin polarization of LaTiO₃ is gained in model TiO₂–FeO₂. Our results demonstrate that the interfacial geometry and hybridization can successfully tune the Fermi energy and the Hubbard band of LaTiO₃, and novel physical properties in different models provide opportunities for developing functional nanoelectronic devices.