High mobility conduction at (110) and (111) LaAlO3/SrTiO3 interfaces

TL;DR

This paper demonstrates high-mobility two-dimensional electron liquids at (110) and (111) LaAlO3/SrTiO3 interfaces, expanding the known conditions for such conductive states beyond the well-studied (001) surface.

Contribution

It reveals that high-mobility 2DEL can be achieved at non-(001) SrTiO3 surfaces, including amorphous interfaces, challenging previous limitations and broadening potential applications.

Findings

High mobility 2DEL at (110) and (111) SrTiO3 surfaces.

Conductive interfaces with amorphous LaAlO3.

Mobility comparable to (001) interfaces.

Abstract

In recent years, striking discoveries have revealed that two-dimensional electron liquids (2DEL) confined at the interface between oxide band-insulators can be engineered to display a high mobility transport. The recognition that only few interfaces appear to suit hosting 2DEL is intriguing and challenges the understanding of these emerging properties not existing in bulk. Indeed, only the neutral TiO2 surface of (001)SrTiO3 has been shown to sustain 2DEL. We show that this restriction can be surpassed: (110) and (111) surfaces of SrTiO3 interfaced with epitaxial LaAlO3 layers, above a critical thickness, display 2DEL transport with mobilities similar to those of (001)SrTiO3. Moreover we show that epitaxial interfaces are not a prerequisite: conducting (110) interfaces with amorphous LaAlO3 and other oxides can also be prepared. These findings open a new perspective both for materials research and for elucidating the ultimate microscopic mechanism of carrier doping.