Weak antilocalization in epitaxial graphene: evidence for chiral electrons

TL;DR

This paper demonstrates weak antilocalization effects in epitaxial graphene on silicon carbide, providing evidence for the chiral nature of electrons, with experimental results aligning with theoretical predictions and revealing unique quantum transport phenomena.

Contribution

It provides experimental evidence of weak antilocalization in epitaxial graphene, confirming the chiral electronic character and identifying scattering mechanisms.

Findings

Observation of broad cusp-like depression in resistance under magnetic fields

Presence of a sharp weak-localization peak at zero magnetic field

Small Shubnikov-de Haas oscillations with anomalous Berry's phase

Abstract

Transport in ultrathin graphite grown on silicon carbide is dominated by the electron-doped epitaxial layer at the interface. Weak anti-localization in 2D samples manifests itself as a broad cusp-like depression in the longitudinal resistance for magnetic fields 10 mT$< B <$ 5 T. An extremely sharp weak-localization resistance peak at B=0 is also observed. These features quantitatively agree with graphene weak-(anti)localization theory implying the chiral electronic character of the samples. Scattering contributions from the trapped charges in the substrate and from trigonal warping due to the graphite layer on top are tentatively identified. The Shubnikov-de Haas oscillations are remarkably small and show an anomalous Berry's phase.