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arXiv · 1404.2556

High-density two-dimensional small polaron gas in a delta-doped Mott insulator

Daniel G. Ouellette·Pouya Moetakef·Tyler A. Cain·Jack Y. Zhang·Susanne Stemmer·David Emin·S. James Allen
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Abstract

Heterointerfaces in complex oxide systems open new arenas in which to test models of strongly correlated material, explore the role of dimensionality in metal-insulator-transitions (MITs) and small polaron formation. Close to the quantum critical point Mott MITs depend on band filling controlled by random disordered substitutional doping. Delta-doped Mott insulators are potentially free of random disorder and introduce a new arena in which to explore the effect of electron correlations and dimensionality. Epitaxial films of the prototypical Mott insulator GdTiO3 are delta-doped by substituting a single (GdO)+1 plane with a monolayer of charge neutral SrO to produce a two-dimensional system with high planar doping density. Unlike metallic SrTiO3 quantum wells in GdTiO3 the single SrO delta-doped layer exhibits thermally activated DC and optical conductivity that agree in a quantitative manner with predictions of small polaron transport but with an extremely high two-dimensional density of polarons, ~ 7E14 cm-2

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Daniel G. Ouellette, Pouya Moetakef, Tyler A. Cain, Jack Y. Zhang, Susanne Stemmer, David Emin, S. James Allen. 2014-04-09. High-density two-dimensional small polaron gas in a delta-doped Mott insulator. https://doi.org/10.1038/srep03284

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