Cyclotron frequency coupled enhancement of Kerr rotation in low refractive index-dielectric/magneto-optic bilayer thin-film structures

Abstract

We investigate the enhancement of magneto-optic polar Kerr rotation over a broad range of optical frequencies. The Drude model for the dielectric tensor is considered. Resonance-like peaks in the Kerr rotation and ellipticity caused in the vicinity of a plasma edge is extended throughout the visible spectrum by deriving an expression for the cyclotron frequency such that Re(⑀ xx )ϳ1 at any given incident photon energy and plasma frequency of the material. The Kerr rotation obtained by use of this expression was studied for the case of InSb and further enhancement of Kerr rotation was achieved in the case of LiF/InSb bilayer thin-film structure, grown on a glass substrate. The numerical analysis was carried out using a 2ϫ2 characteristic matrix, which takes into account multiple reflections and interface effects within the medium. In addition the role of various magneto-optic material parameters and layer thicknesses is investigated in determining the optical frequency at which the maximum Kerr rotation occurs, under the present cyclotron frequency condition. Enhanced Kerr rotation greater than 1.5°over a broad range of optical frequencies was obtained. Tables showing optimum figure of merit for repeated LiF/InSb bilayers at 3.1 eV for different plasma frequencies are also provided.

High figure of merit magneto-optics from interfacial skyrmions on topological insulators

“…From this most commonly used expression for calculating MOKE, it can be seen that MOKE resonances should occur when xx = 1. This is also where R ± goes to zero and the MOKE resonance occurs near ω = ω p [67][68][69]. Note that similarly, magneto-plasmons in graphene give large magneto optic effects [70,71].…”

Enhancement of polar Kerr effect by forming Au nanoparticles on Ni surface

“…Then, it is easy to understand that when K is constant, a reduced R should result in an enhanced ͉ K ͉. However, enhanced ͉ K ͉ ͑at a given value of x m ͒ does not always imply reduced R. 3,4 For example, x m = 100 Å here is an exception. Part of the reason, as mentioned later, is that ͉ K ͉ is enhanced alternatively by an increase in K, while keeping R constant.…”

“…Since then, there has been great advancement of both theoetical [2][3][4] and experimental 5 understanding of the polar Kerr rotation ͑PKR͒ and of the surface plasma resonance ͑SPR͒. In particular, it was shown in Ref.…”

Anomalous Magneto Optic Effects from an Antiferromagnet Topological-Insulator Heterostructure

“…The MOKE in a multilayer thin-film structure can be significantly altered by internal reflection at various interfaces. At normal incidence, r ± for N thin-films can be calculated using a 2 × 2 characteristic matrix method [11,43] in the LCP/RCP eigenmode basis: where β j = (2π/λ)n j d j is a phase factor, d j is the thickness of the j th layer and λ is the optical wavelength. The Fresnel reflection and transmission coefficients at normal incidence for each interface respectively are r ± j,j+1 = (n ± j − n ± j+1 )/(n ± j + n ± j+1 ) and t ± j,j+1 = (2n ± j )/(n ± j + n ± j+1 ).…”