Understanding the onset of negative electronic compressibility in one- and two-band 2D electron gases: Application to LaAlO${}_3$/SrTiO${}_3$

Abstract

We investigate the effects of two electronic bands at 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. Given the difficulty in determining and confirming multi-band electronic systems, this model provides a potential method for identifying multi-band electronic systems using precise bulk electronic properties measurements. To help illustrate this method, we apply our results to the observed NEC in the 2D electron gas at the interface of LaAlO${}_3$/SrTiO${}_3$ (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.

arXiv comment12 Pages, 8 Figures

References in corpus (31)

• Electric Field Control of the LaAlO${}_3$/SrTiO${}_3$ Interface Ground State
• Unveiling a two-dimensional electron gas with universal subbands at the surface of SrTiO3
• Theory of spin-orbit coupling at LaAlO3/SrTiO3 interfaces and SrTiO3 surfaces
• A Universal Critical Density Underlying the Physics of Electrons at the LaAlO3/SrTiO3 Interface
• Profiling the interface electron gas of LaAlO3/SrTiO3 heterostructures by hard X-ray photoelectron spectroscopy
• Dominant mobility modulation by the electric field effect at the LaAlO_3 / SrTiO_3 interface
• Tailoring a two-dimensional electron gas at the LaAlO3/SrTiO3 (001) interface by epitaxial strain
• Large capacitance enhancement and negative compressibility of two-dimensional electronic systems at LaAlO${}_3$/SrTiO${}_3$ interfaces
• Electron-phonon interaction and charge carrier mass enhancement in SrTiO3
• Common Fermi-liquid origin of T-squared resistivity and superconductivity in n-type SrTiO3
• Towards two-dimensional metallic behavior at LaAlO3/SrTiO3 interfaces
• Thermodynamic Signature of a Two-Dimensional Metal-Insulator Transition
• Calculation of the Capacitances of Conductors -- Perspectives for the Optimization of Electronic Devices
• Anomalously large capacitance of a plane capacitor with a two-dimensional electron gas
• Phase separation from electron confinement at oxide interfaces
• Two-band superconductivity in doped SrTiO${}_3$ films and interfaces
• Gate-tunable band structure of the LaAlO${}_3$-SrTiO${}_3$ interface
• Competition between electron pairing and phase coherence in superconducting interfaces
• Electronic compressibility of a graphene bilayer
• Electron-phonon Coupling and the Superconducting Phase Diagram of the LaAlO3-SrTiO3 Interface
• Optically excited multi-band conduction in LaAlO3/SrTiO3 heterostructures
• Strain and ferroelectric soft mode induced superconductivity in strontium titanate
• Insulating phase of a two-dimensional electron gas in MgZnO/ZnO heterostructure below nu = 1/3
• Large Negative Electronic Compressibility of LaAlO3-SrTiO3 Interfaces with Ultrathin LaAlO3 Layers
• Electric field effect on superconductivity at complex oxide interfaces
• Correlation between Superconductivity, Band Filling and Electron Confinement at the LaAlO${}_3$-SrTiO${}_3$ Interface
• Capacitance and compressibility of heterostructures with strong electronic correlations
• Structure-Property Relation of SrTiO3-LaAlO3 Interfaces
• On the Ground State of Electron Gases at Negative Compressibility
• Multiband superconductivity in Pb, H under pressure and CaBeSi from {\it ab-initio} calculations
• Novel mechanisms to enhance the capacitance beyond the classical limits in capacitors with free-electron-like electrodes