Terahertz transition radiation of bulk and surface electromagnetic waves by an electron entering a layered superconductor
Abstract
We theoretically study the transition radiation of bulk and surface electromagnetic waves by an electron crossing an interface between a layered superconductor and an isotropic dielectric. We assume that the direction of the electron motion and the orientation of the superconducting layers are perpendicular to the interface. We derive the analytical expressions for the strongly anisotropic radiation fields and for the timeintegrated energy fluxes of bulk and oblique surface electromagnetic waves (OSWs). We show that the OSWs with frequencies close to the Josephson plasma frequency ω_{J} provide the main contribution to the OSWs energy flux. Moreover, for frequencies close to the Josephson plasma frequency, the spectral density of the OSWs radiation diverges at some critical value of the azimuth angle φ. At the angles φ =0 and φ =90^{o}, the radiation field has a transverse magnetic polarization. We have also studied the Cherenkov radiation by the electron escaping from the layered superconductor and show that this radiation is almost monochromatic. A remarkable feature of the Cherenkov radiation in a layered superconductor is that, contrary to the isotropic case, the Cherenkov radiation distinctly manifests itself in the angular dependence of the radiation energy flux.
 Publication:

Physical Review B
 Pub Date:
 March 2014
 DOI:
 10.1103/PhysRevB.89.094506
 arXiv:
 arXiv:1312.0319
 Bibcode:
 2014PhRvB..89i4506A
 Keywords:

 41.60.m;
 74.25.N;
 Radiation by moving charges;
 Condensed Matter  Superconductivity
 EPrint:
 9 pages, 7 figures, Published in PRB, Vol. 89, No. 9, 094506(9) (2014)