Cathodoluminescence Properties of Ni-Decorated Hexagonal Cr Microrods for Magneto-Plasmonic Applications

Multifunctional low-dimensional non-noble metal nanostructures exhibiting a broad range of plasmonic resonances and magnetic properties are expected to be innovative materials suitable for advanced device applications. In this work, we synthesized Ni-nanoparticle-decorated Cr microrods from Cr/Ni thin films driven by solid-state dewetting. The Cr microrod exhibits the phase evolution of the Cr(FCC) to Cr(HCP) with temperature confirmed by X-ray diffraction and high-resolution transmission microscopy. Cathodoluminescence (CL) imaging and spectroscopy of a single Cr microrod reveal plasmonic modes in UV (315 nm), vis (563 nm), and IR (705 nm) ranges. With a dewetting temperature, the red-shifted CL emission peaks indicate tunable plasmonic modes. The origin of the three plasmonic modes can be understood from the orbital electron density of states for d–d intraband and s–d interband transitions. The Ni nanoparticles decorated on Cr microrods also show significant room temperature ferromagnetism. The Ni-nanoparticle-designed Cr microrods may expand the range of magneto-plasmonic materials beyond noble metals. The combination of plasmonic and magnetic properties could facilitate emission-sensitive detection and therapy in plasmonic-based optoelectronic technology.