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Boltzmann Transport in Nanostructures as a Friction Effect
Andrea Cepellotti1, Nicola Marzari1
1Theory and Simulations of Materials (THEOS) and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland.
Nano Letters
|June 30, 2017
Summary
Surface scattering limits heat transport in crystals. This study reveals heat flow is hydrodynamic, like viscous fluids, due to surface friction, challenging prior models.
Area of Science:
- Condensed matter physics
- Materials science
- Nanoscale thermal transport
Background:
- Surface scattering limits thermal transport in dielectric crystals at reduced length scales or low temperatures.
- Existing models assume mean free paths are crystal-size bound, reducing thermal conductivity proportionally.
- These assumptions and approximated models are shown to be insufficient.
Purpose of the Study:
- To re-evaluate the phenomenon of surface scattering in thermal transport.
- To develop a more accurate model for heat flow in nanostructured materials.
- To provide a method for analyzing thermal properties in specific geometries.
Main Methods:
- Linearized Boltzmann transport equation in the relaxon basis.
- Reduction to a set of decoupled linear differential equations.
- Hydrodynamic interpretation of heat flow with surface friction effects.
Main Results:
- Heat flow is analogous to viscous fluid dynamics near surfaces.
- Demonstrated analysis for monolayer molybdenum disulfide ribbons and trenches.
- Developed procedures to reconstruct temperature and thermal conductivity profiles.
- Quantified the impact of nanostructuring on thermal transport.
Conclusions:
- The hydrodynamic model offers a more accurate description of surface scattering effects.
- The approach is generalizable to other transport carriers (e.g., electrons) and material dimensions/geometries.
- This work provides a framework for understanding and engineering thermal transport in nanostructures.
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