Magnetic-conductivity effects on electromagnetic propagation in dispersive matter

TL;DR

This paper explores how magnetic conductivity, including effects like the Chiral Magnetic Effect, influences electromagnetic wave propagation in dispersive media, revealing phenomena like birefringence and conducting behavior.

Contribution

It introduces a generalized Ohm's law incorporating magnetic conductivity and analyzes its impact on electromagnetic wave propagation, especially in parity-violating scenarios.

Findings

Magnetic conductivity modifies the refractive index of media.

Birefringence occurs due to diagonal magnetic conductivity.

Imaginary parts in refractive indices indicate conducting behavior.

Abstract

The Chiral Magnetic Effect (CME) has been investigated as a new transport phenomenon in condensed matter. Such an effect appears in systems with chiral fermions and involves an electric current generated by a magnetic field by means of an "exotic" magnetic conductivity. This effect can also be connected with extensions of the usual Ohm's law either in magnetohydrodynamics or in Lorentz-violating scenarios. In this work, we study the classical propagation of electromagnetic waves in isotropic dispersive matter subject to a generalized Ohm's law. The latter involves currents linear in the magnetic field and implies scenarios inducing parity violation. We pay special attention to the case of a vanishing electric conductivity. For a diagonal magnetic conductivity, which includes the CME, the refractive index is modified such that it implies birefringence. For a nondiagonal magnetic conductivity, modified refractive indices exhibiting imaginary parts occur ascribing a conducting behavior to a usual dielectric medium. Our findings provide new insight into typical material properties associated with a magnetic conductivity.