In recent years, optical local heating in the nanoscale has attracted great attention due to its unique features of small
hot spot size and high energy density. Plasmonic local heating can provide solutions to several challenges in data storage
and cancer treatment. Research conducted in this field to achieve plasmonic local heating has mainly utilized the
excitation of localized surface plasmon (LSP) or surface plasmon resonance (SPR). However, achieving plasmonic local
heating by the excitation of magnetic polariton (MP) has not been researched extensively yet. We numerically
investigate the optical response of a nanostructure composed of a gold nanowire on a gold surface separated by a
polymer spacer using the ANSYS High Frequency Structural Simulator (HFSS). The structure exhibits a strong
absorption peak at the wavelength of 750 nm, and the underlying physical mechanism is verified by the local
electromagnetic field distribution to be the magnetic resonance excitation. By incorporating the volume loss density due
to the strong local optical energy confinement as the heat generation, nanoscale temperature distribution within the
structure is numerically obtained with a thermal solver after assigning proper boundary conditions. The results show a
maximum temperature of 158.5°C confined in a local area on the order of 35 nm within the ultrathin polymer layer,
which clearly demonstrates the plasmonic local heating effect beyond diffraction limit by excitation of MP.
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