Quantized thermal Conductance via Phononic heat transport in nanoscale devices at low temperatures

  • We study phononic heat transport in nanoscale devices. In the nonequilibrium Green's function formalism, an analytical small-frequency expansion of the phonon current transmission is derived for an arbitrary oscillator chain with typical contact-device-contact structure. Applying this expansion in a Landauer formula, it is possible to construct a systematic low-temperature expansion of the thermal conductance. It follows that quantized thermal conductance occurs as a plateau of the thermal conductance divided by the temperature within second order of the temperature expansion for completely heterogeneous systems as long as the product of force constant and oscillator mass is identical in both contacts, independent of the scattering area. Beyond this plateau, the higher-order terms of the low-temperature expansion yield a finite-temperature correction exhibiting the form of a cubic power law depending on the details of the scattering area. These findings are in agreement with experiments and numerical calculations. Our general resultsWe study phononic heat transport in nanoscale devices. In the nonequilibrium Green's function formalism, an analytical small-frequency expansion of the phonon current transmission is derived for an arbitrary oscillator chain with typical contact-device-contact structure. Applying this expansion in a Landauer formula, it is possible to construct a systematic low-temperature expansion of the thermal conductance. It follows that quantized thermal conductance occurs as a plateau of the thermal conductance divided by the temperature within second order of the temperature expansion for completely heterogeneous systems as long as the product of force constant and oscillator mass is identical in both contacts, independent of the scattering area. Beyond this plateau, the higher-order terms of the low-temperature expansion yield a finite-temperature correction exhibiting the form of a cubic power law depending on the details of the scattering area. These findings are in agreement with experiments and numerical calculations. Our general results are applied to a double junction chain, where we find as the first phenomenon beyond our low-temperature expansion a second plateau. This plateau is associated with a thermal phase averaging of the phonon transmission, which leads for increasing temperatures to an independence of the thermal conductance from the device length.show moreshow less

Export metadata

Additional Services

Search Google Scholar
Metadaten
Author: Mathias Käso, Ulrich Wulf
URL:http://journals.aps.org/prb/abstract/10.1103/PhysRevB.89.134309
DOI:https://doi.org/10.1103/PhysRevB.89.134309
ISSN:2469-9977
Title of the source (English):Physical Review B
Document Type:Scientific journal article peer-reviewed
Language:English
Year of publication:2014
Volume/Year:89
Issue number:13
First Page:134309
Faculty/Chair:Fakultät 1 MINT - Mathematik, Informatik, Physik, Elektro- und Informationstechnik / FG Computational Physics
Einverstanden ✔
Diese Webseite verwendet technisch erforderliche Session-Cookies. Durch die weitere Nutzung der Webseite stimmen Sie diesem zu. Unsere Datenschutzerklärung finden Sie hier.