Two-Dimensional Electron Gas with High Mobility Forming at BaO/SrTiO3 Interface

TL;DR

This paper reports the formation of a high-mobility two-dimensional electron gas at the BaO/SrTiO3 interface, with potential for quantum phase exploration and electronic device applications.

Contribution

It demonstrates the creation of a 2DEG at the BaO/SrTiO3 interface with record-high mobility and provides insights into the charge transfer mechanism responsible.

Findings

Electron mobility reaches 69000 cm^2 V^-1 s^-1 at 2 K.

Observation of Shubnikov-de Haas oscillations indicating 2D Fermi surface.

First-principles calculations link charge transfer to high mobility.

Abstract

Two-dimensional electron gas (2DEG) formed at the interface between two insulating oxides offers an opportunity for fundamental research and device applications. Binary alkaline earth metal oxides possess compatible lattice constants with both silicon and perovskite oxides, exhibiting an enormous potential to bridging those two materials classes for multifunctionalities. Here we report the formation of 2DEG at the interface between the rock-salt BaO and SrTiO3. The highest electron mobility reaches 69000 cm^2 V.S^-1 at 2 K, leading to the typical Shubniko de Haas (SdH) oscillations under the high magnetic fields. The presence of SdH oscillations at different field-angles reveals a quasi-two-dimensional character of the Fermi surface. The first-principles calculations suggest that the effective charge transfer from the BaO to Ti 3dxy orbital at the interfaces is responsible to the observed high carrier mobility. Our results demonstrate that the BaO/STO heterointerface is a platform for exploring the correlated quantum phases, opening a door to the low-power and mesoscopic electronic devices.