Singh, Vijeta and Pulikkotil, J. J. (2017) Mixed valence as a necessary criteria for quasi-two dimensional electron gas in oxide hetero-interfaces. Solid State Communications, 251. pp. 28-31. ISSN 0038-1098

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The origin of quasi-two dimensional electron gas at the interface of polar-nonpolar oxide hetero-structure,such as LaAlO3/SrTiO3, is debated over electronic reconstruction and defects/disorder models. Common to these models is the partial valence transformation of substrate Ti ions from its equilibrium 4 + state to an itinerant 3 + state. Given that the Hf ions have a lower ionization potential than Ti due to the 4f orbital screening, one would expect a hetero-interface conductivity in the polar-nonpolar LaAlO3/SrHfO3 system as well. However, our first principles calculations show the converse. Unlike the Ti3+ - Ti4+ valence transition which occur at a nominal energy cost, the barrier energy associated with its isoelectronic Hf3+ - Hf4+ counterpart is very high, hence suppressing the formation of quasi-two dimensional electron gas at LaAlO3/SrHfO3 hetero-interface. These calculations, therefore, emphasize on the propensity of mixed valence at the interface as a necessary condition for an oxide hetero-structure to exihibit quasi two-dimensional electron gas.

Item Type: Article
Additional Information: Copyright for this article belongs to M/s Elsevier.
Subjects: Applied Physics/Condensed Matter
Depositing User: Users 27 not found.
Date Deposited: 12 Nov 2018 07:23
Last Modified: 12 Nov 2018 07:23

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