# 2019 CAP Congress / Congrès de l'ACP 2019

2-7 June 2019
Simon Fraser University
America/Vancouver timezone
Welcome to the 2019 CAP Congress Program website! / Bienvenue au siteweb du programme du Congrès de l'ACP 2019 !

## Possible Flexoelectric Origin of the Lifshitz Transition in Strontium Titanate Interfaces

Jun 5, 2019, 1:15 PM
15m
ASB 10900 (Simon Fraser University)

### ASB 10900

#### Simon Fraser University

Oral (Non-Student) / Orale (non-étudiant(e)) Condensed Matter and Materials Physics / Physique de la matière condensée et matériaux (DCMMP-DPMCM)

### Speaker

Bill Atkinson (Trent University)

### Description

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.

### Primary authors

Bill Atkinson (Trent University) Amany Raslan (Trent University)