Exciton swapping in a twisted graphene bilayer as a solid-state realization of a two-brane model

It is shown that exciton swapping between two graphene sheets may occur under specific conditions. A magnetically tunable optical filter is described to demonstrate this new effect. Mathematically, it is shown that two turbostratic graphene layers can be described as a "noncommutative" two-sheeted (2+1)-spacetime thanks to a formalism previously introduced for the study of braneworlds in high energy physics. The Hamiltonian of the model contains a coupling term connecting the two layers which is similar to the coupling existing between two braneworlds at a quantum level. In the present case, this term is related to a K-K' intervalley coupling. In addition, the experimental observation of this effect could be a way to assess the relevance of some theoretical concepts of the braneworld hypothesis.Comment: 15 pages, 3 figures, final version published in European Physical Journal

Photoinduced quantum magnetotransport properties of silicene and germanene

Silicene and germanene have remarkable electronic properties due to strong spin orbit coupling and buckled single layer structures. We derive and analyze the band structures of these materials in the presence of perpendicular electric and magnetic fields taking into account the effects of off-resonant light. Using linear response theory, analytical expressions are derived and evaluated for the Hall and longitudinal conductivities. Contrary to graphene, we show that the light leads to a single Dirac cone state and thus to unusual plateaus and magnetotransport properties, which are desirable for electronic applications