A new route to negative refractive index from topological metals

TL;DR

This paper proposes a theoretical method to achieve negative refractive index in Weyl/Dirac semimetals by leveraging the chiral magnetic effect and plasma gap, expanding possibilities for novel optical materials.

Contribution

It introduces a new theoretical approach to realize negative refractive index using topological metals and the axial anomaly effects.

Findings

Negative refractive index occurs below plasma frequency.

Chiral magnetic effect enables negative refraction in topological metals.

Reflection and transmission properties are characterized for Weyl/Dirac semimetals.

Abstract

We theoretically discuss the possibility of realizing the negative refractive index in Weyl/Dirac semimetals. We consider the Maxwell equations with the plasma gap and the chiral magnetic effect. We study the dispersion relations of electromagnetic waves, and show that the refractive index becomes negative at frequencies (just) below the plasma frequency. We find that axial anomaly, or more specifically, negative magnetoresistance (electric current parallel to magnetic fields) opens a new route to realize the negative refractive index. Reflection and transmission coefficients are computed in a slab of Weyl/Dirac semimetals.