Possible Flexoelectric Origin of the Lifshitz Transition in LaAlO${}_3$/SrTiO${}_3$ Interfaces

Abstract

Multiple experiments have observed a sharp transition in the band structure of LaAlO${}_3$/SrTiO${}_3$ (001) interfaces as a function of applied gate voltage. This Lifshitz transition, between a single occupied band at low electron density and multiple occupied bands at high density, is remarkable for its abruptness. In this work, we propose a mechanism by which such a transition might happen. We show via numerical modeling that the simultaneous coupling of the dielectric polarization to the interfacial strain ("electrostrictive coupling") and strain gradient ("flexoelectric coupling") generates a thin polarized layer whose direction reverses at a critical density. The Lifshitz transition occurs concomitantly with the polarization reversal and is first-order at $T=0$. A secondary Lifshitz transition, in which electrons spread out into semiclassical tails, occurs at a higher density.

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Cited by in corpus (6)

• Oxygen vacancies and hydrogen doping in LaAlO3/SrTiO3 heterostructures: electronic properties and impact on surface and interface reconstruction
• Tunable spin and orbital polarization in SrTiO3-based heterostructures
• Twin Boundary Mediated Flexoelectricity in LaAlO${}_3$
• Evolution of domain structure with electron doping in ferroelectric thin films
• Mechanism for Switchability in Electron-Doped Ferroelectric Interfaces
• Modified transverse Ising model for the dielectric properties of SrTiO${}_3$ films and interfaces