Backscattering limit of nanoscale heat conduction.

Being able to achieve extremely low thermal conductivities is of fundamental importance as well as of practical interest for thermal energy conversion and storage materials. By incorporating backscattering effects on thermal phonon transport, here we introduce a new lower limit for the thermal conductivities of nanoscale engineered materials. Our formulation shows that surface backscattering allows to reach a minimum limit for thermal energy transport at the nanoscale, achieving thermal conductivities which are orders of magnitude smaller than those obtained with classical approaches.