Room-temperature quantum transport signatures in graphene/LaAlO3/SrTiO3 heterostructures

TL;DR

This study demonstrates that graphene devices on LaAlO3/SrTiO3 heterostructures exhibit pseudospin quantum interference effects, such as weak antilocalization, persisting at room temperature, which is promising for practical quantum device applications.

Contribution

It reports the fabrication and characterization of graphene on LaAlO3/SrTiO3, showing room-temperature quantum transport signatures, a novel finding for complex-oxide heterostructures.

Findings

Weak antilocalization persists up to room temperature.

LaAlO3/SrTiO3 substrate suppresses impurity scattering.

Quantum transport signatures are unique to this system.

Abstract

The pseudospin quantum degree of freedom is one of the most remarkable properties of graphene that distinguishes it from ordinary two-dimensional metals and semiconductors. Pseudospin quantum interference leads to weak antilocalization (WAL) and is influenced strongly by point defects and thermal perturbations that break chirality and destroy phase coherence. Preserving and manipulating quantum transport properties up to room temperature is key to realizing practical pseudospin-based graphene devices. Here we report fabrication and transport characterization of graphene field-effect devices on a complex-oxide heterostructure, LaAlO3/SrTiO3. Signatures of WAL, a consequence of pseudospin quantum interference, persist up to room temperature. The LaAlO3/SrTiO3 substrate plays a critical role in suppressing short-range impurity scattering and electron-phonon coupling. The observation of quantum transport signatures at room temperature is unique to this system and presents new opportunities for the development of pseudospin-based devices and novel multifunctional devices that couple to the complex-oxide interface.