Irreversible multi-band effects and Lifshitz transitions at the LaAlO3/SrTiO3 interface under field effect

TL;DR

This study explores how electric fields induce irreversible changes in the multiband electronic structure of LaAlO3/SrTiO3 interfaces, revealing Lifshitz transitions and the effects of disorder and temperature on these processes.

Contribution

It demonstrates that both crystalline and amorphous LaAlO3/SrTiO3 interfaces exhibit similar irreversible band filling and depletion behaviors under electric fields, leading to Lifshitz transitions.

Findings

Irreversible charge depletion affects higher and three-dimensional bands more.

Filling and depletion patterns are similar in crystalline and amorphous interfaces.

Temperature and disorder influence the extent of band depletion.

Abstract

In this work, we investigate the irreversible effects of an applied electric field on the magnetotransport properties of LaAlO3/SrTiO3 conducting interfaces, with focus on their multiband character. We study samples of different types, namely with either crystalline or amorphous LaAlO3 overlayer. Our two-band analysis highlights the similarity of the electronic properties of crystalline and amorphous interfaces, regardless much different carrier densities and mobilities. Furthermore, filling and depletion of the two bands follow very similar patterns, at least in qualitative terms, in the two types of samples. In agreement with previous works on crystalline interfaces, we observe that an irreversible charge depletion takes place after application of a first positive back gate voltage step. Such charge depletion affects much more, in relative terms, the higher and three-dimensional dyz, dzx bands than the lower and bidimensional dxy, driving the system through the Lifshitz transition from two-band to single band behavior. The quantitative analysis of experimental data evidences the roles of disorder, apparent in the depletion regime, and temperature. Noteworthy, filling and depletion of the two bands follow very similar patterns in crystalline and amorphous samples, at least in qualitative terms, regardless much different carrier densities and mobilities.