Possible Mott physics in SrTiO$_3$/GdTiO$_3$ superlattices

ORAL

Abstract

We perform generalized gradient approximation (GGA) + Hubbard U to study the thickness-dependent metal to insulator transition in SrTiO$_3$/GdTiO$_3$ superlattices. A full structural optimization procedure is applied, showing significant electronic and structural reconstruction near the interface between the band insulator SrTiO$_3$ and Mott insulator GdTiO$_3$. In addition, we find high charge density at the interface, close to half electron per interface unit cell (pseudo-cubic notation). For the insulating ultra-thin SrTiO$_3$ layer case, we are able to describe it by a low energy effective Hamiltonian. Using Hartree-Fock approximation, we find the combining effect of the hopping parameters and the correlation in the $d$ orbitals of Ti can lead to possible Mott insulating state. Finally, magnetism is also studied and compared with the GGA+U result.

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Authors

  • Ru Chen

    Department of Physics, University of California, Santa Barbara, CA-93106-9530, UC Santa Barbara

  • SungBin Lee

    Department of Physics, University of Toronto, Ontario, Canada, M5S 1A7

  • Leon Balents

    Kavli Institute for Theoretical Physics, University of California, Santa Barbara, Kavli Institute for Theoretical Physics, University of California, Santa Barbara, Santa Barbara, California 93106, USA, Kavli Institute of Theoretical Physics, UCSB, Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA-93106-9530