Magnetic Resonance\nModulation in Ferrocene-alkyne\nConjugated Polymer for Electromagnetic Wave Absorption

Abstract

Dielectric loss and magnetic loss are two necessary factors\nin\nelectromagnetic wave absorption, but there are few works that can\nstudy magnetic factors alone because of the limitations of the material\nitself. This work achieved the transformation from a nonmagnetic polymer\n(PFc-1) to a superparamagnetic polymer (PFc-3) by introducing alkyne\nunits to regulate the valence state of iron atoms in the ferrocene\nunit. It also accomplished the transition of wave-absorbing properties\nfrom nonexistent to present. The extremely low dielectric loss of\nthe polymer itself also provides a good background for studying magnetic\nlosses. After characterization, the maximum reflection loss of PFc-3\nunder the action of exchange resonance reaches −31.7 dB. Through\ndensity functional theory (DFT) calculations, we can speculate on\nthe specific mechanism of exchange resonance in PFc-3: under the influence\nof specific external sources, the single-electron energy level structure\nof Fe changes. The frequency jumps, creating a resonance. This work\nopens up a perspective for the application of magnetic regulation\nin the field of electromagnetic absorption.