• Ghosh, Kalyan
• Samal, Prasanjit
• Sahoo, Subhashree
• Patra, Bikash

Abstract

<jats:title>Abstract</jats:title><jats:p>Manipulating light at the sub-wavelength level is a crucial feature of surface plasmon resonance (SPR) properties for a wide range of nanostructures. Noble metals like Au and Ag are most commonly used as SPR materials. Significant attention is being devoted to identify and develop non-noble metal plasmonic materials whose optical properties can be reconfigured for plasmonic response by structural phase changes. Chromium (Cr) which supports plasmon resonance, is a transition metal with shiny finished, highly non-corrosive, and bio-compatible alloys, making it an alternative plasmonic material. We have synthesized Cr micro-rods from a bi-layer of Cr/Au thin films, which evolves from face centered cubic to hexagonal close packed (HCP) phase by thermal activation in a forming gas ambient. We employed optical absorption spectroscopy and cathodoluminescence (CL) imaging spectroscopy to observe the plasmonic modes from the Cr micro-rod. The origin of three emission bands that spread over the UV–Vis-IR energy range is established theoretically by considering the critical points of the second-order derivative of the macroscopic dielectric function obtained from density functional theory (DFT) matches with interband/intraband transition of electrons observed in density of states versus energy graph. The experimentally observed CL emission peaks closely match the <jats:italic>s</jats:italic>–<jats:italic>d</jats:italic> and <jats:italic>d</jats:italic>–<jats:italic>d</jats:italic> band transition obtained from DFT calculations. Our findings on plasmonic modes in Cr(HCP) phase can expand the range of plasmonic material beyond noble metal with tunable plasmonic emissions for plasmonic-based optical technology.</jats:p>

Topics

• density
• impedance spectroscopy
• surface
• chromium
• phase
• theory
• thin film
• density functional theory
• forming
• activation
• surface plasmon resonance spectroscopy