title: Ferroplasmons: intense localized surface plasmons in metal-ferromagnetic nanoparticles.
abstract: Interaction of photons with matter at length scales far below their wavelengths has given rise to many novel phenomena, including localized surface plasmon resonance (LSPR). However, LSPR with narrow bandwidth (BW) is observed only in a select few noble metals, and ferromagnets are not among them. Here, we report the discovery of LSPR in ferromagnetic Co and CoFe alloy (8% Fe) in contact with Ag in the form of bimetallic nanoparticles prepared by pulsed laser dewetting. These plasmons in metal-ferromagnetic nanostructures, or ferroplasmons (FP) for short, are in the visible spectrum with comparable intensity and BW to those of the LSPRs from the Ag regions. This finding was enabled by electron energy-loss mapping across individual nanoparticles in a monochromated scanning transmission electron microscope. The appearance of the FP is likely due to plasmonic interaction between the contacting Ag and Co nanoparticles. Since there is no previous evidence for materials that simultaneously show ferromagnetism and such intense LSPRs, this discovery may lead to the design of improved plasmonic materials and applications. It also demonstrates that materials with interesting plasmonic properties can be synthesized using bimetallic nanostructures in contact with each other.
authors: Department of Materials Science and Engineering, University of Tennessee , Knoxville, Tennessee 37996, United States.
authors: Ritesh
authors: R
authors: Sachan
authors: Abhinav
authors: A
authors: Malasi
authors: Jingxuan
authors: J
authors: Ge
authors: Sagar
authors: S
authors: Yadavali
authors: Hare
authors: H
authors: Krishna
authors: Anup
authors: A
authors: Gangopadhyay
authors: Hernando
authors: H
authors: Garcia
authors: Gerd
authors: G
authors: Duscher
authors: Ramki
authors: R
authors: Kalyanaraman
keywords: bimetallic nanoparticles; electron energy-loss spectroscopy; ferromagnet; hybridization; localized surface plasmon resonance; scanning transmission electron microscopy; silver