Phase and Conductivity‐Controlled Surface Plasmon Polaritons in Hybrid Nanocomposite Systems

ABSTRACT We theoretically investigate how complex surface conductivity governs surface plasmon polaritons (SPPs) at the interface of hybrid plasmonic nanosystems composed of atomic and nanocomposite media. By introducing a tunable conductivity parameter, we analyze the influence of both its magnitude and phase on SPP behavior. The dispersion analysis reveals that smaller phases lead to stronger mode confinement, whereas larger phases broaden the spectral response. The effective mode index demonstrates controllable localization, with enhanced confinement at low and gradual delocalization as increases. Propagation characteristics indicate a balance between absorption and phase modulation, where intermediate phases optimize SPP transport by extending the propagation length. Penetration depth analysis shows complementary energy redistribution: low phases concentrate the field within the atomic medium, while higher phases shift energy deeper into the nanocomposite region. In addition, the rotary drag effect exhibits pronounced asymmetry governed by conductivity phase and spin frequency, enabling reversible control of both the sign and magnitude of the rotational response through or the external angular velocity . These results demonstrate that conductivity magnitude and phase provide powerful knobs for tailoring dispersion, confinement, penetration, and rotational dynamics of SPPs, opening new avenues for advanced plasmonic devices in nanoscale light manipulation, quantum photonics, and hybrid plasmonic information processing.