skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Metallic Interface at the Boundary Between Band and Mott Insulators

Abstract

Motivated by experiments on atomically smooth layers of LaTiO3, a Mott insulator, sandwiched between layers of SrTiO3, a band insulator, a simple model for such heterostructures is studied using quasi one-dimensional lattices and the Lanczos method. Taking both the local and long-range Coulomb interactions into account, and computing the layer dependent local density of states, a metallic state was found at the interface whose extent strongly depends on the dielectric constant of the material. We also observed that the antiferromagnetic correlations in the bulk Mott phase persist into the metallic region. Our conclusions are in excellent agreement with recently reported results for this model in the opposite limit of infinite dimensions6,7, thus providing an alternative tool to study electronic reconstruction effects in heterostructures.

Authors:
 [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Science (SC)
OSTI Identifier:
931707
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review B; Journal Volume: 74
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; LANTHANUM OXIDES; STRONTIUM OXIDES; ELECTRICAL INSULATORS; PERMITTIVITY; INTERFACES; TITANIUM OXIDES; MATHEMATICAL MODELS; COULOMB FIELD; metallic interface; Mott

Citation Formats

Kancharla, Srivenkateswara S, and Dagotto, Elbio R. Metallic Interface at the Boundary Between Band and Mott Insulators. United States: N. p., 2006. Web. doi:10.1103/PhysRevB.74.195427.
Kancharla, Srivenkateswara S, & Dagotto, Elbio R. Metallic Interface at the Boundary Between Band and Mott Insulators. United States. doi:10.1103/PhysRevB.74.195427.
Kancharla, Srivenkateswara S, and Dagotto, Elbio R. Sun . "Metallic Interface at the Boundary Between Band and Mott Insulators". United States. doi:10.1103/PhysRevB.74.195427.
@article{osti_931707,
title = {Metallic Interface at the Boundary Between Band and Mott Insulators},
author = {Kancharla, Srivenkateswara S and Dagotto, Elbio R},
abstractNote = {Motivated by experiments on atomically smooth layers of LaTiO3, a Mott insulator, sandwiched between layers of SrTiO3, a band insulator, a simple model for such heterostructures is studied using quasi one-dimensional lattices and the Lanczos method. Taking both the local and long-range Coulomb interactions into account, and computing the layer dependent local density of states, a metallic state was found at the interface whose extent strongly depends on the dielectric constant of the material. We also observed that the antiferromagnetic correlations in the bulk Mott phase persist into the metallic region. Our conclusions are in excellent agreement with recently reported results for this model in the opposite limit of infinite dimensions6,7, thus providing an alternative tool to study electronic reconstruction effects in heterostructures.},
doi = {10.1103/PhysRevB.74.195427},
journal = {Physical Review B},
number = ,
volume = 74,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • We investigate the ground state phase diagram of the half-filled repulsive Hubbard model in two dimensions in the presence of a staggered potential ?, the so-called ionic Hubbard model, using cluster dynamical mean field theory. We find that for large Coulomb repulsion, U , the system is a Mott insulator (MI). For weak to intermediate values of ?, on decreasing U, the Mott gap closes at a critical value Uc1(?) beyond which a correlated insulating phase with possible bond order (BO) is found. Further, this phase undergoes a first-order transition to a band insulator (BI) at Uc2(?) with a finitemore » charge gap at the transition. For large ?, there is a direct first-order transition from a MI to a BI with a single metallic point at the phase boundary« less
  • In a recent Letter, Yoshimatsu et al. [1] used soft x-ray photoemission to probe electronic structure at the buried epitaxial LaAlO3/SrTiO3(001) interface (LAO/STO). This system has been of significant recent interest because of reports of two-dimensional electron gas (2-DEG) behavior at the interface of two band insulators. Although oxygen vacancies in the STO can result in itinerant electrons, an intrinsic conducting layer appears to form, possibly originating with interface charge from LAO which allegedly alleviates the so-called “polar catastrophe” at the interface. The principal conclusions from [1] are: (i) there is no partially-reduced Ti at the interface, as expected ifmore » there is electron transfer from the LAO, and, (ii) band bending at the interface occurs and results in a quantum well which is populated with carriers in the case of the TiO2-terminated substrate, but not for the SrO-terminated substrate. While the first of these conclusions is defensible, the second is not.« less
  • A gas of strongly interacting single-species (spinless) p-orbital fermionic atoms in 2D optical lattices is proposed and studied. Several interesting new features are found. In the Mott limit on a square lattice, the gas is found to be described effectively by an orbital exchange Hamiltonian equivalent to a pseudospin-1/2 XXZ model. For a triangular, honeycomb, or kagome lattice, the orbital exchange is geometrically frustrated and described by a new quantum 120 deg. model. We determine the orbital ordering on the kagome lattice, and show how orbital wave fluctuations select ground states via the order by disorder mechanism for the honeycombmore » lattice. We discuss experimental signatures of various orbital ordering.« less
  • We investigate the general structure of orbital exchange physics in Mott-insulating states of p-orbital systems in optical lattices. Orbital orders occur in both the triangular and kagome lattices. In contrast, orbital exchange in the honeycomb lattice is frustrated as described by a novel quantum 120 deg. model. Its classical ground states are mapped into configurations of the fully packed loop model with an extra U(1) rotation degree of freedom. Quantum orbital fluctuations select a six-site plaquette ground state ordering pattern in the semiclassical limit from the 'order from disorder' mechanism. This effect arises from the appearance of a zero energymore » flat band of orbital excitations.« less