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Lattice thermal conductance in nanowires at low temperatures: Breakdown and recovery of quantization

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Title: Lattice thermal conductance in nanowires at low temperatures: Breakdown and recovery of quantization
Authors: Tanaka, Y.1 Browse this author →KAKEN DB
Yoshida, F. Browse this author
Tamura, S. Browse this author
Authors(alt): 田中, 之博1
Issue Date: 2005
Publisher: American Physical Society
Volume: 71
Start Page: 205308
Publisher DOI: 10.1103/PhysRevB.71.205308
Abstract: The quantization of lattice thermal conductance g normalized by g0=π2k2BT/3h (the universal quantum of thermal conductance) was recently predicted theoretically to take an integer value over a finite range of temperature and then observed experimentally in nanowires with catenoidal contacts. The prediction of this quantization by Rego and Kirczenow [Phys. Rev. Lett. 81, 232 (1998)] relies on a study of only dilatational (longitudinal) vibrational mode in the wires. We study the thermal conductance in catenoidal wires by explicitly calculating the transmission rates of the six distinct vibrational modes (four acoustic and two low-lying optical modes) and applying the Landauer formula for the one-dimensional thermal transport in the ballistic regime. In a temperature range similar to the one predicted by Rego and Kirczenow, we find the presence of a plateau in g/g0. However, below this temperature range g/g0 is modified—that is, the quantization is broken—due to imperfect transmission of the acoustic modes of vibration. Our new observation is that, as temperature goes down further, the recovery of the quantization of g/g0 should occur. These results are found assuming GaAs as a wire material, but we also make similar calculations for silicon nitride wires used experimentally.
Rights: Copyright © 2005 American Physical Society
Type: article
Appears in Collections:工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 田中 之博

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