ABSTRACT
What is the thermal conductivity of silicon nanowires, n-alkane single molecules, carbon nanotubes, or thin lms? How does the conductivity depend on the nanowire dimension, nanotube chirality, molecular length and temperature, or the lm thickness and disorder? More profoundly, what are the mechanisms of heat transfer at the nanoscale, in constrictions, at low temperatures? Recent experiments and theoretical studies have demonstrated that the thermal conductivity of nanolevel systems signi cantly differ from their macroscale analogs [1]. In macroscopic-continuum objects, heat ows diffusively, obeying the Fourier’s law (1808) of heat conduction, J = –KT, J is the current, K is the thermal conductivity and T is the temperature gradient across the structure. It is however obvious that at small scales, when the phonon mean free path is of the order of the device dimension, distinct transport mechanisms dominate the dynamics. In this context, one would like to understand the violation of the Fourier’s
law, derive complete set of necessary and suf cient conditions for its validity, and ultimately derive it from rst principle arguments [2].
