# Waveguide Modes in Weyl Semimetals with Tilted Dirac Cones

## TL;DR

This paper theoretically investigates electromagnetic guided wave modes in Weyl semimetals with tilted Dirac cones, revealing conditions for highly localized waves, tunable energy confinement, and controllable energy flow velocity.

## Contribution

It introduces a theoretical framework for understanding waveguiding in Weyl semimetals, highlighting the effects of cone tilt and anisotropy on mode localization and energy transport.

## Key findings

- Ultrathin Weyl semimetal structures support localized guided waves.
- Tunable epsilon-near-zero response enables energy confinement.
- System power can vanish depending on tilt and frequency.

## Abstract

We theoretically study unattenuated electromagnetic guided wave modes in centrosymmetric Weyl semimetal layered systems. By solving Maxwell's equations for the electromagnetic fields and using the appropriate boundary conditions, we derive dispersion relations for propagating modes in a finite-sized Weyl semimetal. Our findings reveal that for ultrathin structures, and proper Weyl cones tilts, extremely localized guided waves can propagate along the semimetal interface over a certain range of frequencies. This follows from the anisotropic nature of the semimetal where the diagonal components of the permittivity can exhibit a tunable epsilon-near-zero response. From the dispersion diagrams, we determine experimentally accessible regimes that lead to high energy-density confinement in the Weyl semimetal layer. Furthermore, we show that the net system power can vanish all together, depending on the Weyl cone tilt and frequency of the electromagnetic wave.These effects are seen in the energy transport velocity, which demonstrates a substantial slowdown in the propagation of electromagnetic energy near critical points of the dispersion diagrams. Our results can provide guidelines in designing Weyl semimetal waveguides that can offer efficient control in the velocity and direction of energy flow.