Diffraction-limited phonon thermal conductance of nanoconstrictions

Thermal transport across nanosized constrictions is calculated considering wave effects. It is shown that Rayleigh-type phonon diffraction reduces thermal transport across nanosized constrictions at low temperatures. We show that for aT/vDebye<0.01×10−9KsaT∕vDebye<0.01×10−9Ks, where aa is the radius of the constriction, TT the temperature, and vDebyevDebye the Debye velocity of the solid material, diffraction effects are important.