Propagation of Dirac waves through various temporal interfaces, slabs, and crystals

Abstract

We investigate the influence of the temporal variations of various medium parameters on the propagation of Dirac-type waves in materials where the quasiparticles are described by a generalized version of the pseudospin-1/2 Dirac equation. Our considerations also include the propagation of electromagnetic waves in metamaterials with the Dirac-type dispersion. We focus on the variations of the scalar and vector potentials, mass, Fermi velocity, and tilt velocity describing the Dirac cone tilt. We derive the scattering coefficients associated with the temporal interfaces and slabs analytically and find that the temporal scattering is caused by the changes of the mass, Fermi velocity, and vector potential, but does not arise from the changes of the scalar potential and tilt velocity. We also explore the conditions under which the temporal Brewster effect and total interband transition occur and calculate the change in total wave energy. We examine bilayer Dirac temporal crystals where parameters switch between two different sets of values periodically and prove that these systems do not have momentum gaps. Finally, we assess the potential for observing these temporal scattering effects in experiments.

12 pages, 7 figures

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• Dirac materials
• Dirac fermions in borophene
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• Temporal Brewster angle
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Cited by in corpus (6)

• Electron Scattering at a Potential Temporal Step Discontinuity
• Spatial localization and diffusion of Dirac particles and waves induced by random temporal medium variations
• Deterministic time rewinding of waves in time-varying media
• Statistical regimes of electromagnetic wave propagation in randomly time-varying media
• Access to Klein Tunneling via Space-Time Modulation
• Disorder-enabled directional delocalization and wave steering in time-modulated Dirac materials