Plasmon Weyl Degeneracies in Magnetized Plasma

TL;DR

This paper discovers Weyl points in magnetized plasma, revealing topological features like Fermi arcs and chiral reflection behavior, which could enable novel topological photonic devices.

Contribution

It introduces the concept of Weyl photonics in homogeneous magnetized plasma, demonstrating topological features in a naturally existing material.

Findings

Identification of Weyl points in magnetized plasma dispersion

Observation of chiral reflection behavior near Weyl points

Presence of Fermi arcs connecting Weyl points

Abstract

In this letter, we report the presence of novel type of plasmon Weyl points in a naturally existing material - magnetized plasma. In such a medium, conventional, purely longitudinal bulk plasma oscillations exists only along the direction of applied magnetic field (z direction). With strong enough magnetic field, there exist helical propagating modes along z direction with circular polarizations. The orthogonality between the longitudinal bulk plasmon mode and the transverse helical propagating modes guarantees their crossing at the bulk plasmon frequency. These crossing points, embedded in the bulk plasmon dispersion line, serve as monopoles in the k space - the so called Weyl points. These Weyl points lead to salient observable features. These include the highly intriguing observation that, at a magnetized plasma surface which is parallel to the applied magnetic field, reflection of an electromagnetic wave with in-plane wave-vector close to the Weyl points exhibits chiral behavior only in half of the k plane, which is bounded by the projection of the bulk plasmon dispersion line. We also verify the presence of 'Fermi arcs' connecting the two Weyl points with opposite chiralities when magnetized plasma interfaces with trivial photonic materials. Our study introduces the concept of Weyl photonics into homogeneous strongly dispersive photonic materials, which could pave way for realizing new topological photonic devices.