Electrostatic carrier doping of GdTiO$_{3}$/SrTiO$_{3}$ heterostructures

ORAL

Abstract

Two-dimensional electron gases (2DEGs) at interfaces between Mott insulators and band insulators have attracted significant attention because they can exhibit unique properties, such as strong electron correlations, superconductivity and magnetism. At interfaces between SrTiO$_{3}$ and the rare earth titanates (Mott insulators) an interfacial fixed polar charge arises due to a polarization discontinuity, which can be compensated by a 2DEG, residing in the bands of the Mott/band insulator. In this presentation, we report on intrinsic electronic reconstructions at a Mott/band insulator interface between stoichiometric GdTiO$_{3}$ and SrTiO$_{3}$ that were grown using molecular beam epitaxy. The sheet carrier densities of all GdTiO$_{3}$/SrTiO$_{3}$ heterostructures containing more than one unit cell of SrTiO$_{3}$ are approximately 1/2 electron per unit cell, independent of layer thickness and growth sequence. These carrier densities closely meet the electrostatic requirements for compensating the fixed charge at these polar interfaces. Based on the experimental measurements, insights into the location and confinement of the charge and the influence of different electrostatic boundary conditions are obtained.

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Authors

  • Pouya Moetakef

    Materials Department, University of California Santa Barbara, UC Santa Barbara

  • Tyler Cain

    Materials Department, University of California Santa Barbara, UC Santa Barbara

  • Daneil Ouellette

    Physics Department, University of California Santa Barbara

  • Jack Zhang

    Materials Department, University of California Santa Barbara

  • Clayton Jackson

    Materials Department, University of California Santa Barbara, UC Santa Barbara

  • Siddharth Rajan

    The Ohio State University, Department of Electrical and Computer Engineering, Ohio State University, Ohio State University

  • Jim Allen

    UC Santa Barbara - Physics, Physics, UCSB, University of California at Santa Barbara, Physics Department, University of California Santa Barbara, UC Santa Barbara, ITST, Department of Physics, University of California, Santa Barbara

  • Susanne Stemmer

    UC Santa Barbara - Materials, Materials, UCSB, Materials Department, University of California Santa Barbara, UC Santa Barbara, University of California, Santa Barbara