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arXiv · 1905.12088

Reversed electromagnetic Vavilov-\v{C}erenkov radiation in naturally existing magnetoelectric media

O. J. Franca·L. F. Urrutia·Omar Rodríguez-Tzompantzi
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Abstract

We consider two semi-infinite magnetoelecteric media separated by a planar interface whose electromagnetic response is described by axion-electrodynamics. The time dependent Green's function characterizing this geometry is obtained by a method which can be directly generalized to cylindrical and spherical configurations of two magnetoelectrics separated by an interface. We establish the far-field approximation of the Green's function and apply these results to the case of a charged particle moving from one medium to the other at a high constant velocity perpendicular to the interface. From the resulting angular distribution of the radiated energy per unit frequency we provide theoretical evidence for the emergence of reversed Vavilov-\v{C}erenkov radiation in naturally existing magnetoelectric media. In the case where one of the magnetolectrics is a 3D topological insulator, ${\rm TlBiSe}_2$ for example, located in front of a regular insulator, we estimate that an average forward Vavilov-\v{C}erenkov radiation with frequency $\sim 2.5 \,\, {\rm eV}$ ($\sim 500\,\, {\rm nm}$) will produce a highly suppressed reversed Vavilov-\v{C}erenkov radiation which can be characterized by an effective frequency in the range of $\sim (4\times 10^{-3}-0.5) \,\, {\rm meV}$. However, this value compares favorably with recent measurements in left-handed metamaterials yielding reversed Vavilov-\v{C}erenkov radiation with frequencies of the order of $(1.2-3.9)\times 10^{-2}\,\, {\rm meV}$.

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O. J. Franca, L. F. Urrutia, Omar Rodríguez-Tzompantzi. 2019-05-26. Reversed electromagnetic Vavilov-\v{C}erenkov radiation in naturally existing magnetoelectric media. https://doi.org/10.1103/physrevd.99.116020

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