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 difference induced by switching the polarization's handedness has been limited to only a few hundred millikelvins to a few kelvins. 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 of chiral plasmonic nanostructures made from titanium nitride, which has a thermal conductivity less than 10% that of gold, can be switched by as much as several tens of kelvins when irradiated with circularly polarized light: 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.