Anomalously strong pinning of the filling factor nu=2 in epitaxial graphene

TL;DR

This study demonstrates that epitaxial graphene on SiC exhibits exceptionally stable quantum Hall states at filling factor nu=2 over a broad magnetic field range, enabling highly precise resistance measurements for metrology.

Contribution

It reveals the anomalously strong pinning of the nu=2 Landau level in epitaxial graphene, enhancing its potential for quantum resistance standards.

Findings

Achieved a Hall resistance quantization precision of 3 parts in 10^10.

Observed broad magnetic field range with filled zero-energy Landau level.

Demonstrated robustness of quantum Hall effect in epitaxial graphene.

Abstract

We explore the robust quantization of the Hall resistance in epitaxial graphene grown on Si-terminated SiC. Uniquely to this system, the dominance of quantum over classical capacitance in the charge transfer between the substrate and graphene is such that Landau levels (in particular, the one at exactly zero energy) remain completely filled over an extraordinarily broad range of magnetic fields. One important implication of this pinning of the filling factor is that the system can sustain a very high nondissipative current. This makes epitaxial graphene ideally suited for quantum resistance metrology, and we have achieved a precision of 3 parts in 10^10 in the Hall resistance quantization measurements.