Influence of 0001 tilt grain boundaries on the destruction of the quantum Hall effect in graphene
Journal article, 2015

The half-integer quantum Hall effect (QHE) is often suppressed in graphene grown by chemical vapor deposition on metals. The reason behind the suppression is unclear, and we hypothesize that it might be connected to extended defects in the material. In this paper we present results for the quantum Hall effect in graphene with [0001] tilt grain boundaries connecting opposite sides of Hall bar devices. Such grain boundaries contain 5-7 ring complexes that host defect states that hybridize to form bands with varying degree of metallicity depending on grain-boundary defect density. In a magnetic field, edge states on opposite sides of the Hall bar can be connected by the defect states along the grain boundary. This destroys Hall resistance quantization and leads to nonzero longitudinal resistance. Anderson disorder can partly recover quantization, where current instead flows along returning paths along the grain boundary depending on defect density in the grain boundary and on disorder strength. Since grain sizes in graphene made by chemical vapor deposition are usually small, this may help explain why the quantum Hall effect is usually poorly developed in devices made of this material.

Author

Anders Bergvall

Chalmers, Microtechnology and Nanoscience (MC2), Applied Quantum Physics

J. M. Carlsson

Tomas Löfwander

Chalmers, Microtechnology and Nanoscience (MC2), Applied Quantum Physics

Physical Review B - Condensed Matter and Materials Physics

1098-0121 (ISSN)

Vol. 91 24

New Electronics Concept: Wafer-Scale Epitaxial Graphene (ConceptGraphene)

European Commission (FP7), 2010-10-01 -- 2013-09-30.

Subject Categories

Condensed Matter Physics

DOI

10.1103/PhysRevB.91.245425

More information

Created

10/8/2017