title: Thermal transport in phononic Cayley-tree networks.
abstract: We analytically investigate the heat current I and its thermal fluctuations Δ in a branching network without loops (Cayley tree). The network consists of two types of harmonic masses: vertex masses M placed at the branching points where phononic scattering occurs and masses m at the bonds between branching points where phonon propagation takes place. The network is coupled to thermal reservoirs consisting of one-dimensional harmonic chains of coupled masses m. Due to impedance mismatch phenomena, both I and Δ are non-monotonic functions of the mass ratio μ=M/m. Furthermore, we find that in the low-temperature limit the thermal conductance approaches zero faster than linearly due to the small transmittance of the long-wavelength modes.
authors.affiliation: Department of Physics, Wesleyan University, Middletown, Connecticut 06459, USA.
authors.forename: Huanan
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Physics, Wesleyan University, Middletown, Connecticut 06459, USA.
authors.forename: Tsampikos
authors.initials: T
authors.lastname: Kottos
authors.affiliation: Technion - Israel Institute of Technology, Technion City, Haifa 32000, Israel.
authors.forename: Boris
authors.initials: B
authors.lastname: Shapiro