A high-mobility two-dimensional electron gas at the heteroepitaxial spinel/perovskite complex oxide interface of {\gamma}-Al2O3/SrTiO3

TL;DR

This paper reports the creation of a high-mobility two-dimensional electron gas at the heterointerface of SrTiO3 and { extgamma}-Al2O3, surpassing previous mobility limits and enabling advanced oxide electronic devices.

Contribution

It introduces a novel spinel/perovskite heterointerface that achieves significantly higher electron mobility than traditional perovskite interfaces.

Findings

Electron mobility exceeds 10,000 cm2V-1s-1 at low temperatures.

Quantum magnetoresistance oscillations confirm 2D conduction.

The 2DEG is confined within 0.9 nm near the interface.

Abstract

The discovery of two-dimensional electron gases (2DEGs) at the heterointerface between two insulating perovskite-type oxides, such as LaAlO3 and SrTiO3, provides opportunities for a new generation of all-oxide electronic and photonic devices. However, significant improvement of the interfacial electron mobility beyond the current value of approximately 1,000 cm2V-1s-1 (at low temperatures), remains a key challenge for fundamental as well as applied research of complex oxides. Here, we present a new type of 2DEG created at the heterointerface between SrTiO3 and a spinel {\gamma}-Al2O3 epitaxial film with excellent quality and compatible oxygen ions sublattices. This spinel/perovskite oxide heterointerface exhibits electron mobilities more than one order of magnitude higher than those of perovskite/perovskite oxide interfaces, and demonstrates unambiguous two-dimensional conduction character as revealed by the observation of quantum magnetoresistance oscillations. Furthermore, we find that the spinel/perovskite 2DEG results from interface-stabilized oxygen vacancies and is confined within a layer of 0.9 nm in proximity to the heterointerface. Our findings pave the way for studies of mesoscopic physics with complex oxides and design of high-mobility all-oxide electronic devices.