We demonstrate how to control the spectra and current flow of Dirac electrons in both a graphene sheet and a topological insulator (TI) by applying either two linearly polarized laser fields with frequencies ω and 2ω or a monochromatic (one-frequency) laser field together with a spatially periodic static potential (graphene/TI superlattice). Using the Floquet theory and the resonance approximation, we show that a Dirac point in the electron spectrum can be split into several Dirac points whose relative location in momentum space can be efficiently manipulated by changing the characteristics of the laser fields. In addition, the laser-field-controlled Dirac fermion band structure - a Dirac fermion time-Floquet crystal - allows the manipulation of the electron currents in graphene and topological insulators. Furthermore, the generation of dc currents of desirable intensity in a chosen direction occurs when the biharmonic laser field is applied, which can provide a straightforward experimental test of the predicted phenomena.
Funding
This work has been supported by the Engineering and Physical Sciences Research Council under the grant EP/H049797/1, the Leverhulme Trust and the project MOSAICO.
History
School
Science
Department
Physics
Published in
Physical Review B - Condensed Matter and Materials Physics
Volume
89
Issue
15
Citation
RODRIGUEZ-LOPEZ, P., BETOURAS, J.J. and SAVEL'EV, S., 2014. Dirac fermion time-Floquet crystal: Manipulating Dirac points. Physical Review B - Condensed Matter and Materials Physics, 89, 155132
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