University of Connecticut

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MS Dissertation Defense

Monday, August 8, 2022
12:00pm – 2:00pm


Graduate Student Aditi Mahabir, Department of Physics, University of Connecticut

Negative electronic compressibility in multiband electron gas models

In this thesis, I present the results of my investigation of the effects of two electronic bands on the negative electronic compressibility (NEC) in a two-dimensional electron gas (2DEG). We use a simple homogeneous model with Coulombic interactions and first-order multi-band coupling to examine the role of effective mass and relative permittivity in relation to the critical carrier density, where compressibility turns negative. We demonstrate that the population of a second band, along with the presence of inter-band coupling, can dramatically change the cross-over carrier density. This model suggests a method for identifying multi-band electronic systems using precise bulk electronic properties measurements despite the difficulty in confirming such systems. We apply our results to the observed NEC in the 2D electron gas at the interface of LaAlO3 and SrTiO3 (LAO/STO) and determine that, for the known parameters of LAO/STO, the system is likely a realization of a two-band 2D electron gas. Furthermore, we provide general limits on the inter-band coupling with respect to the electronic band population.

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Prof. A. Balatsky

Physics Department (primary), College of Liberal Arts and Sciences, UConn Master Calendar

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