Weyl semimetals in circularly-polarized ultrafast laser field

Fatemeh Nematollahi; Vadym Apalkov; Mark I. Stockman

doi:10.1117/12.2506689

4 March 2019 Weyl semimetals in circularly-polarized ultrafast laser field

Fatemeh Nematollahi, Vadym Apalkov, Mark I. Stockman

Proceedings Volume 10908, Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XIX; 1090803 (2019) https://doi.org/10.1117/12.2506689
Event: SPIE LASE, 2019, San Francisco, California, United States

Abstract

We theoretically study the interaction of three dimensional topological Weyl semimetals with an ultrafast circularly polarized optical pulse. We use the lower-energy approximation of the full Hamiltonian of the system in the reciprocal space near the Weyl points. We present the results for TaAs, which has two pairs of Weyl points. The ultrafast pulse causes a finite electron conduction band population both during and after the pulse. We show that the electron dynamics for such materials is coherent and highly irreversible, i.e., the residual conduction band population is comparable to the maximum conduction band population during the pulse. For a pulse propagating in the z direction, the large population of electrons is located near the Weyl points and along the separatrix which is defined as a set of the initial points for which electron trajectories in the reciprocal space pass precisely through the (k_x, k_y) = (0, 0) point for different values of k_z. For small k_z, the system behaves similar to graphene and, the interband dipole matrix elements are highly localized near (k_x, k_y) = (0, 0) point and the conduction band population has sharp maximum along the separatrix. However, for large k_z, the system behaves as a gapped graphene with delocalized interband dipole matrix and the transfer of electrons between the valence band and the conduction bands are not confined within a narrow region. We also show that the optical pulse causes electrical current and net charge transfer through the system during the pulse.

Citation Download Citation

Fatemeh Nematollahi, Vadym Apalkov, and Mark I. Stockman "Weyl semimetals in circularly-polarized ultrafast laser field", Proc. SPIE 10908, Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XIX, 1090803 (4 March 2019); https://doi.org/10.1117/12.2506689

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