Publication: Floquet engineering of Dirac cones on the surface of a topological insulator
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2019-08-06
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American Physical Society
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Abstract
We propose to Floquet engineer Dirac cones at the surface of a three-dimensional topological insulator. We show that a large tunability of the Fermi velocity can be achieved as a function of the polarization, direction, and amplitude of the driving field. Using this external control, the Dirac cones in the quasienergy spectrum may become elliptic or massive, in accordance with experimental evidence. These results help us to understand the interplay of surface states and external ac driving fields in topological insulators. In our work we use the full Hamiltonian for the three-dimensional system instead of effective surface Hamiltonians, which are usually considered in the literature. Our findings show that the Dirac cones in the quasienergy spectrum remain robust even in the presence of bulk states, and therefore, they validate the usage of effective surface Hamiltonians to explore the properties of Floquet-driven topological boundaries. Furthermore, our model allows us to introduce out-of-plane field configurations which cannot be accounted for by effective surface Hamiltonians.
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©2019 American Physical Society
The authors thank P. Rodriguez for very enlightening discussions. This research was supported by MINECO (Grants No. MAT2016-75955 and No. MAT2017-86717-P). A.D.-F. acknowledges support from the UCM-Santander Program (Grant No. CT27/16-CT28/16), and A.G.-L. acknowledges the Juan de la Cierva program. A.G.-L. and G.P. acknowledge support from the CSIC Research Platform PTI-001.