Fibonacci quasiperiodic structures for enhanced polar magneto-optical Kerr response

The polar magneto-optical Kerr effect (PMOKE) is a key mechanism for optical readout, but conventional materials respond only weakly. Magnetophotonic crystals enhance the PMOKE via interference-driven light confinement, yet Fibonacci designs remain largely unexplored in the polar geometry and insufficiently benchmarked against other orderings. Using a 4 \(\times\) 4 transfer-matrix formalism, we calculate the Kerr rotation, reflectance, and their product, the figure of merit (FOM), for one-dimensional Fibonacci magnetophotonic quasiperiodic structures of cobalt (Co) and silicon nitride (SiN) layers as functions of Co thickness, wavelength, generation order (up to the eighth), and incidence angle. Fibonacci ordering yields Kerr enhancement at specific Co thicknesses, attributed to interference-driven field localization within the Co layers, and the enhancement remains robust for incidence angles up to about \(20^\circ\) . With increasing generation order, the Kerr rotation decreases, but the reflectance rises proportionally more, so the FOM generally increases. A comparison of the 8th-generation structure with all 1287 possible arrangements of the same length and composition shows that the strongest responses come from sequences whose local ordering is closest to the Fibonacci pattern, indicating that the specific correlations of the Fibonacci sequence, rather than the loss of periodicity or the layer-type ratio alone, underlie the enhancement.