A minimal discrete model for toroidal moments and its experimental realization
Abstract
It is well known that a closed loop of magnetic dipoles can give rise to the rather elusive toroidal moment. However, artificial structures required to generate the necessary magnetic moments in metamaterials are typically optically large, complex to make, and easily compromised by the kinetic inductance at high frequencies. Instead of using magnetic dipoles, we propose a minimal model based on just three aligned discrete electric dipoles in which the occurrence of resonant toroidal modes is guaranteed by symmetry. The advantage of this model is its simplicity and the same model supports toroidal moments from the microwave regime up to optical frequencies as exemplified by a threeantenna array and a system consisting of three nanosized plasmonic particles. Both the microwave and highfrequency configurations exhibit nonradiating "anapoles." Experiments in the microwave regime confirm the theoretical predictions.
 Publication:

Physical Review B
 Pub Date:
 January 2017
 DOI:
 10.1103/PhysRevB.95.045403
 arXiv:
 arXiv:1605.02282
 Bibcode:
 2017PhRvB..95d5403X
 Keywords:

 Physics  Optics;
 Condensed Matter  Mesoscale and Nanoscale Physics
 EPrint:
 21 pages, 6 figures