Talk given by Dr. Rebeca Ribeiro We report on the observation of strong backscattering of charge carriers in the quantum Hall regime of polycrystalline graphene grown by chemical vapor deposition, which alters the accuracy of the Hall resistance quantization. The temperature and magnetic field dependence of the longitudinal conductivity exhibits unexpectedly smooth power law behaviors, which are incompatible with a description in terms of variable range hopping or thermal activation, but rather suggest the existence of extended or poorly localized states at energies between Landau levels. Such states could be caused by the high density of line defects (grain boundaries and wrinkles) that cross the Hall bars, as revealed by structural characterizations. Numerical calculations confirm that quasi-1D extended non-chiral states can form along such line defects and short- circuit the Hall bar chiral edge states.

This event is part of the eventgroup INT Talks

Homepage
https://www.int.kit.edu/events.php

Speaker
Dr. Rebeca Ribeiro

Laboratoire National de Metrologie et d'essais (LNE)

Organizer
Dr. Romain Danneau
Institute of Nanotechnology (INT)
Karlsruhe Institute of Technology (KIT)
Eggenstein-Leopoldshafen
Tel: 0721/608-28896
Mail: romain danneau ∂does-not-exist.kit edu

Targetgroup
Interested / Everyone