Nanoscale Seebeck effect at hot metal nanostructures

Aboubakry Ly (1) , Arghya Majee (2, 3) , Alois Würger (1)

1 LOMA - Laboratoire Ondes et Matière d'Aquitaine
2 Max-Planck-Institut für Intelligente Systeme
3 Institute fürTheoretische Physik IV

We theoretically study the Seebeck effect in the vicinity of a heated metal nanostructure, such as the cap of an active Janus colloid in an electrolyte, or gold-coated interfaces in optofluidic devices. The thermocharge accumulated at the surface varies with the local temperature, thus modulating the diffuse part of the electric double layer. On a conducting surface with non-uniform temperature, the isopotential condition imposes a significant polarization charge within the metal. Surprisingly, this does not affect the slip velocity, which takes the same value on insulating and conducting surfaces. Our results for specific-ion effects agree qualitatively with recent observations for Janus colloids in different electrolyte solutions. Comparing the thermal, hydrodynamic, and ion diffusion time scales, we expect a rich transient behavior at the onset of thermally powered swimming, extending to microseconds after switching on the heating.

Domaines: Matière Molle [cond-mat.soft]

Aboubakry Ly, Arghya Majee, Alois Würger. Nanoscale Seebeck effect at hot metal nanostructures. New Journal of Physics, 2018, 20, pp.025001. ⟨10.1088/1367-2630/aaa266⟩. ⟨hal-01699638⟩