Four distinct surface temperature patterns induced by plasmonic heating of U-shaped Cr2N nanostructures

Chromium nitride (Cr 2 N) is a plasmonic material whose real part of the dielectric function becomes negative in the deep-ultraviolet region, enabling plasmon resonances to be tuned from the ultraviolet to the visible and near-infrared by structural design. Its relatively large imaginary part is also advantageous for thermoplasmonic applications. In addition, Cr 2 N exhibits a low thermal conductivity (12 W m -1 K -1 ) compared with that of noble metals. Here, we numerically demonstrate a U-shaped Cr2N nanostructure that generates four distinct surface temperature distributions, controlled solely by the polarization of monochromatic light at 1064 nm. Owing to its symmetry, the U-shaped structure supports different plasmon modes for horizontal and vertical linear polarizations, as well as for left- and right-handed circular polarizations. These mode differences lead to distinct Joule heating distributions that, due to the low thermal conductivity, are directly imprinted on the surface temperature patterns. As a result, the U-shaped nanostructure acts as a polarization-controlled nanoheater, exhibiting distinct temperature distributions for each polarization state. This result shows that surface temperature distributions can be controlled through plasmon mode design in nanostructures, analogous to the shaping of optical near fields by plasmon modes, which is important for thermoplasmonic applications.