Experimental investigation of interaction of very low frequency electromagnetic waves with metallic nanostructure

The interaction of low-frequency electromagnetic waves with metallic nanostructure consisting of nanoparticles has been investigated. The existence of helicons in metallic nanostructure is predicted based on the enhancement of effective mass of the electrons in metallic mesostructures in low-frequency electromagnetic field. The enhancement of the effective mass of electrons subjected to low-frequency electromagnetic field results in the suppression of the cyclotron frequency. When the excitation frequency approaches the cyclotron frequency, helicons can be observed, which in typical metals occur at MHz frequencies. With the decrease in the cyclotron frequency in nanostructures, the helicons can be observed at low frequencies. We present an experimental setup to detect and image helicon resonances in metallic nanostructures at low frequencies and room temperature conditions. The approach is based on modifying an existing atomic force microscope to image surface topography and the magnetic field images of helicon waves simultaneously in metallic nanoparticles. The magnetic field images of the helicon waves and different resonance modes are presented for platinum nanoparticles deposited using through thin film ablation. The contrast in the magnetic field images is explained based on the generation of resonance modes due to helicon wave propagation in the nanostructure. The features in the helicon resonance images are examined as a function of the particle size and frequency of the electromagnetic wave. (C) 2011 American Institute of Physics. [doi:10.1063/1.3587238]