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Dimensional and Mode Dependent Thermal Transport in Low-dimensional Systems

Dimensional and Mode Dependent Thermal Transport in Low-dimensional Systems. Collaborators: Jian-Sheng Wang , NUS. Jian Wang Yangzhou University ( 扬州大学 ), China. Outline. Nonequilibrium Green’s function method and Mode-Matching’s approach for thermal transport

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Dimensional and Mode Dependent Thermal Transport in Low-dimensional Systems

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  1. Dimensional and Mode Dependent Thermal Transport in Low-dimensional Systems Collaborators: Jian-Sheng Wang, NUS Jian Wang Yangzhou University (扬州大学), China

  2. Outline • Nonequilibrium Green’s function method and Mode-Matching’s approach for thermal transport • Dimensional crossover of thermal conductance in nanowires • Mode dependent thermal transmission in carbon nanotubes • Conclusions and remarks

  3. Nonequilibrium Green’s function method J.-S. Wang, J. Wang, N. Zeng, Phys. Rev. B {74}, 033408 (2006). Left Lead, TL Right Lead, TR

  4. Nonequilibrium Green’s function method For the elastic systems: Laudauer formula

  5. Mode-Matching’s approach where • Dynamic equation in the junction

  6. Mode-Matching’s approach • Energy conservation relations Energy Reflection: Energy Transmission: J Wang and J-S Wang, Phys. Rev. B {74}, 054303 (2006).

  7. Mode-Matching’s approach Ando’s method for computting the transmission amplititudes Phys. Rev. B 44, 8017(1991)

  8. Dimensional crossover of thermal conductance in nanowires J. Wang and J.-S. Wang, Appl. Phys. Lett. {90}, 241908 (2007).

  9. Dimensional crossover of thermal conductance in nanowires

  10. Dimensional crossover of thermal conductance in nanowires

  11. Mode dependent thermal transmission in carbon nanotubes J. Wang and J.-S. Wang, ( in preparation) Carbon Nanotube (11, 0)

  12. Mode dependent thermal transmission in carbon nanotubes LA (A2u ) transmission

  13. Mode dependent thermal transmission in carbon nanotubes TA (E1u ) transmission

  14. Mode dependent thermal transmission in carbon nanotubes TW (A2g ) transmission

  15. Conclusions and remarks • NGF and mode matching method is exact for the elastic scatterings of phonon, such as dects. • Purely ballistic thermal transport in nanowires (with d>10 nm) at low temperatures will behave as T3. • Phonons with lower group velocities will be scattered strongly by the SW defect in CNT. • More efficient method are needed for the consideration of nonlinear interaction in the quantum regime.

  16. Thanks • Prof. Jian-Sheng Wang, NUS • Prof. Bao-Wen Li, NUS • Thanks for your attention!

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