Chiral Plasmonic Surface Temperature Switching by Several Tens of Kelvins in Titanium Nitride Nanostructures.

The strong asymmetric optical response of plasmonic metal nanostructures to right- and left-handed circularly polarized light has attracted great interest in nanotechnology. However, when considering heat generation in these structures, the surface temperature distribution becomes nearly isothermal regardless of which handedness of circularly polarized light is used. This is because of the high thermal conductivity of noble metals and the diffusive nature of heat transfer. In this study, we experimentally show that the surface temperature patterns of chiral plasmonic nanostructures made from titanium nitride, which has a thermal conductivity less than 10% that of gold, become clearly different under right- and left-circularly polarized light, with the temperature contrast reaching several tens of kelvins. This temperature switching allows nanoscale spatial control of photothermal chemical reactions. Our findings suggest a significant potential for shaping nanoscale temperature distributions in the field of thermoplasmonics.