Promotionsvortrag Physik: Charge transport in epitaxial graphene on silicon carbide (0001): The role of mosaic-like disorder

Jan 19
19. Januar 2018 12:00 Uhr bis 12:30 Uhr
Raum SR 00.103, Angewandte Physik, Staudtstraße 7 (Bau A3), 91058 Erlangen

Einladung zum Promotionsvortrag von Herrn Ferdinand Kißlinger:
„Charge transport in epitaxial graphene on silicon carbide (0001): The role of mosaic-like disorder“

With the advent of atomically thin materials, as well as topological insulators, the fundamentals of charge transport in two dimensions can be critically reinvestigated. Usually, such experiments try to achieve low defect density in order to uncover the unperturbed physics of the perfect 2D lattice.
In this talk, we take a different perspective and explicitly assume imperfections in 2D conductors. The material of choice is large-area epitaxial graphene, but many of the considered phenomena are intrinsic to any 2D conductor.
In a first step, it is elaborated that a spatially varying conductivity leads to an apparent logarithmic increase of the resistivity towards low temperatures. This effect can easily be misinterpreted as Kondo effect but is solely caused by a variation of amplitude in the well-characterized electron-electron-interaction correction.
In a second step, experimental magnetoresistiviy data 𝜌𝜌(𝐵𝐵) of bilayer graphene is presented, which displays a strictly linear increase above 𝐵𝐵∼1 T up to the highest magnetic fields 𝐵𝐵∼65 T. This rather unusual effect can be traced back to the network of partial dislocations, the natural line defects in bilayer graphene, which pervade the 2D plane completely. Their consequence is a reshaping of current pathways, which leads to a mixing of longitudinal and Hall currents, and finally to a linear in 𝐵𝐵 resistivity. This is a special case of the so-far enigmatic phenomenon of linear magnetoresistivity, which we are able to explain with a conceptually simple model. (Vortrag auf Deutsch)

Dem Vortrag schließt sich eine Diskussion von 15 Minuten an. Vortrag und Diskussion sind öffentlich. Diesen Verfahrensteilen folgt ein nicht öffentliches Rigorosum von 45 Minuten.