Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session F44: Manifestations of Phonon Hydrodynamics in Thermal TransportInvited
|
Hide Abstracts |
Sponsoring Units: DCMP Chair: Andrea Cepellotti, University of California, Berkeley Room: BCEC 210C |
Tuesday, March 5, 2019 11:15AM - 11:51AM |
F44.00001: Novel Vistas in Thermal Transport: Relaxons, Frictions, Viscosities, and Coherences Invited Speaker: Nicola Marzari We examine the emergence of correlated transport phenomena in systems described by the linearized Boltzmann transport equation (LBTE), with examples then centered around heat transport. First, we show how phonons, traditionally considered the carriers of heat, are only a high-temperature approximation to the exact carriers, that we term relaxons, showing how thermal conductivity can be mapped exaclty into a kinetic theory of the relaxon gas, and where the effect of boundaries can be understood in terms of frictions. Second, we show how the LBTE admits coherent propagating solutions with well defined wavevectors and lifetimes, of which second sound is a special case. Last, we discuss generalizations towards the Navier-Stokes continuum, and towards disordered materials. Work performed in collaboration with Andrea Cepellotti (UC Berkeley), Michele Simoncelli (EPFL), and Francesco Mauri (Sapienza U. of Rome). |
Tuesday, March 5, 2019 11:51AM - 12:27PM |
F44.00002: Observation of the Poiseuille flow of phonons in black phosphorus Invited Speaker: Yo Machida The travel of heat in an insulating solid is commonly pictured as a flow of phonon quasi-particles. In such a picture, phonons are decelerated by scattering with each other. However, in rare circumstances, momentum-conserving scattering between phonons dominate, and phonons can enter a hydrodynamic regime, where they flow like fluids inside a crystalline lattice and retard only by hitting the sample boundaries. This phenomenon dubbed “phonon Poiseuille flow”, which is a phononic counterpart of the Poiseuille flow in classical hydrodynamics, was thought to occur only in ultrapure solids. |
Tuesday, March 5, 2019 12:27PM - 1:03PM |
F44.00003: Phonon Hydrodynamics in Graphene and Graphite Invited Speaker: Gang Chen In the hydrodynamic regime, phonons drift with a nonzero collective velocity under a temperature gradient, reminiscent of viscous gas and fluid flow. The study of hydrodynamic phonon transport has spanned over half a century but has been mostly limited to cryogenic temperatures (<20 K). Recently, we predict based on first principles calculations that hydrodynamic phonon transport can occur in suspended graphene at significantly higher temperatures and wider temperature ranges compared to bulk materials. Furthermore, we identified graphite as a three-dimensional material that supports phonon hydrodynamics at significantly higher temperatures (~100 K). The significant hydrodynamic nature of phonon transport in graphite is attributed to its strong intralayer sp2 hybrid bonding and weak van der Waals interlayer interactions. The hydrodynamic transport is manifested through drift motion of phonons, phonon Poiseuille flow, and second sound. Recent experiments demonstrating second sound up to 100K will be discussed. |
Tuesday, March 5, 2019 1:03PM - 1:39PM |
F44.00004: Thermal conductivity of strontium titanate: signatures of phonon hydrodynamics Invited Speaker: Kamran Behnia Temperature dependence of thermal conductivity in strontium titanate reveals four different regimes of heat flow between 2K and 400 K. At high temperature, in the kinetic regime, phonons are scattered off each other by Umklapp processes and thermal conductivity is inversely proportional to temperature. At low temperature, their mean-free-path is set by domain boundaries. This is the ballistic regime. Between these two limits, one can detect the Ziman regime where Umklapp events are rare. The hybridization of soft optical phonon with acoustic phonons enhance Normal (momentum-conseving) collisions and leads to a faster-than cubic temperature dependence of thermal conductivity in a narrow tempearture window. This is a hallmark of Poiseuille flow of phonons previously observed in a handful of solids. |
Tuesday, March 5, 2019 1:39PM - 2:15PM |
F44.00005: Hydrodynamic heat transport in semiconductors at the nanoscale Invited Speaker: Xavier Alvarez Recent experiments in heat transport on silicon using ultrafast laser heating techniques have shown significant discrepancies with Fourier like behaviour[1-3]. The interpretations of these results using only a ballistic to diffusive transition of the carriers have shown to be unfruitful. The consequence is that heat transport at the nanoscale is still an incompletely described topic. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700