[9p-PB7-1~6] 4.1 Plasmonics and Nanophotonics

English Presentation

[9p-PB7-1] Room-Temperature Negative Dielectric Response Driven by Plasmonic Oscillations in Sr-Doped LaFeO3 for Electromagnetic Shielding Applications

〇(D)Rajni Baranwal¹, Shail Upadhyay¹ (1.Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi)

Keywords:

Plasmonic,Electromagnetic wave attenuation,XPS

Functional oxide materials exhibiting anomalous dielectric behaviour have attracted growing interest for next-generation electromagnetic and photonic technologies. In the present work, La1-xSrxFeO3 (x=0-0.5) ceramics were synthesised using the conventional solid-state reaction route to investigate the influence of Sr substitution on their structural, optical, dielectric, electrical, and electromagnetic properties. X-ray diffraction analysis confirms the formation of an orthorhombic phase with composition-dependent lattice modification upon Sr incorporation. X-ray photoelectron spectroscopy (XPS) measurements revealed the presence of iron in three different oxidation states. UV–visible spectroscopy reveals systematic band-gap modulation associated with Sr-induced electronic structure alteration. Dielectric measurements in the radio-frequency regime exhibit room-temperature negative permittivity behaviour over a broad frequency range. The observed response follows Drude-type dispersion, indicating plasmonic-like carrier oscillations and enhanced charge carrier dynamics within the material system. The significant enhancement in conductivity induced by Sr doping promotes carrier delocalisation and plasmonic-like oscillatory behaviour within the material system. Fitting of the experimental dielectric response using the Drude model enables estimation of the plasma frequency and damping frequency, supporting the carrier-driven origin of the observed negative permittivity [1]. In addition, the samples demonstrate appreciable electromagnetic interference (EMI) shielding performance in the GHz region, highlighting their capability for electromagnetic wave attenuation.