Unusual sign-changing Faraday effect in nanometer-thick magnetic films

Fuente: arXiv
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Bibliographic Details
Main Authors: Belkova, A. V., Ignatyeva, D. O., Kalish, A. N., Vetoshko, P. M., Kudryashov, A. L., Belotelov, V. I.
Format: Preprint
Published: 2025
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author Belkova, A. V.
Ignatyeva, D. O.
Kalish, A. N.
Vetoshko, P. M.
Kudryashov, A. L.
Belotelov, V. I.
author_facet Belkova, A. V.
Ignatyeva, D. O.
Kalish, A. N.
Vetoshko, P. M.
Kudryashov, A. L.
Belotelov, V. I.
contents It is generally believed that the magneto-optical Faraday effect appears in the the bulk of a magnetic material and its sign is fully determined by the sign of the non-diagonal permittivity element. Here we reveal an additional contribution to the Faraday effect from the film interfaces. It becomes notable for films with a thickness of a few tens of nanometers. As a result, in the absorption band of the film a novel feature of the Faraday effect is experimentally observed and numerically confirmed: sign of the Faraday rotation at a fixed wavelength becomes dependent on the film thickness and therefore is ambiguously related to the sign of the gyration and magnetization of the film. We elaborated an analytical model taking into account an interplay between the bulk and surface contributions which nicely describes the experimental data. Moreover, the Faraday rotation coming purely from interfaces without any bulk contribution is demonstrated. Possible applications of the observed unusual Faraday rotation behavior include hardware data encryption and other devices performing polarization control at nanoscale.
format Preprint
id arxiv_https___arxiv_org_abs_2511_20373
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Unusual sign-changing Faraday effect in nanometer-thick magnetic films
Belkova, A. V.
Ignatyeva, D. O.
Kalish, A. N.
Vetoshko, P. M.
Kudryashov, A. L.
Belotelov, V. I.
Optics
It is generally believed that the magneto-optical Faraday effect appears in the the bulk of a magnetic material and its sign is fully determined by the sign of the non-diagonal permittivity element. Here we reveal an additional contribution to the Faraday effect from the film interfaces. It becomes notable for films with a thickness of a few tens of nanometers. As a result, in the absorption band of the film a novel feature of the Faraday effect is experimentally observed and numerically confirmed: sign of the Faraday rotation at a fixed wavelength becomes dependent on the film thickness and therefore is ambiguously related to the sign of the gyration and magnetization of the film. We elaborated an analytical model taking into account an interplay between the bulk and surface contributions which nicely describes the experimental data. Moreover, the Faraday rotation coming purely from interfaces without any bulk contribution is demonstrated. Possible applications of the observed unusual Faraday rotation behavior include hardware data encryption and other devices performing polarization control at nanoscale.
title Unusual sign-changing Faraday effect in nanometer-thick magnetic films
topic Optics
url https://arxiv.org/abs/2511.20373