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arXiv · 2401.03016

Pseudo-proper two-dimensional electron gas formation

Daniel Bennett·Pablo Aguado-Puente·Emilio Artacho·Nicholas Bristowe
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Abstract

In spite of the interest in the two-dimensional electron gases (2DEGs) experimentally found at surfaces and interfaces, important uncertainties remain about the observed insulator--metal transitions (IMTs). Here we show how an explicit improper coupling of carrier sources with a relevant soft mode significantly affects the transition. The analysis presented here for 2DEGs at polar interfaces is based on group theory, Landau-Ginzburg theory, and illustrated with first-principles calculations for the prototypical case of the LaAlO$_3$/SrTiO$_3$ interface, for which such a structural transition has recently been observed. This direct coupling implies that the appearance of the soft mode is always accompanied by carriers. For sufficiently strong coupling an avalanche-like first-order IMT is predicted.

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Daniel Bennett, Pablo Aguado-Puente, Emilio Artacho, Nicholas Bristowe. 2024-01-05. Pseudo-proper two-dimensional electron gas formation. https://doi.org/10.1088/1367-2630/ad8180

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