Observation of second sound in graphite over 200 K

Ding, Zhiwei; Chen, Ke; Song, Bai; Shin, Jungwoo; Maznev, A. A.; Nelson, Keith A.; Chen, Gang

doi:10.1038/s41467-021-27907-z

Cited by 62 publications

(39 citation statements)

References 57 publications

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“…The existence of such phonons follows from the onedimensionality or two-dimensionality of the molecular systems. Therefore, we should expect second sound in such two-dimensional systems as graphene (graphite) [16,17], hexagonal boron nitride (h-BN), and in quasione-dimensional systems such as graphene and h-BN nanotubes, linear cumulene macromolecule [44], and planar zigzag polyethylene. In quasi-one-dimensional systems, second sound manifests itself more strongly than in quasi-two-dimensional systems, since bending vibrations of the former make a greater contribution to heat transfer.…”

Section: Discussionmentioning

confidence: 99%

“…The second sound can also be determined from the relaxation scenario of the initial periodic sinusoidal temperature profile (from the relaxation of the temperature lattice). Note that in the experimental works [16,17] the second sound in graphite was determined from the analysis of relaxation of the temperature lattice.…”

Section: Relaxation Of a Periodic Thermal Latticementioning

confidence: 99%

“…15. Thus, the classical molecular dynamics does not allow to simulate temperature waves experimentally observed in graphite [16,17]. Therefore, it is fundamentally important to take into account the quantum statistics of thermal phonons for modeling the second sound in quasione-dimensional and two-dimensional molecular systems.…”

Section: Comparison With Classical Molecular Dynamicsmentioning

confidence: 99%

“…Second sound, or hydrodynamic phonon transfer, is observed between ballistic and diffusion regimes of heat transfer. In two-dimensional (2D) materials, second sound can be observed at temperatures above 100K [16][17][18], and for rapidly changing temperature high-frequency second sound can also be observed in three-dimensional (3D) materials at higher temperatures [19].…”

Section: Introductionmentioning

confidence: 99%

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Modeling of second sound in carbon nanostructures

Savin,

Kivshar

2022

Preprint

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The study of thermal transport in low-dimensional materials has attracted a lot of attention recently after discovery of high thermal conductivity of graphene. Here we study numerically phonon transport in low-dimensional carbon structures being interested in the hydrodynamic regime revealed through the observation of second sound. We demonstrate that correct numerical modeling of such two-dimensional systems requires semi-classical molecular dynamics simulations of temperature waves that take into account quantum statistics of thermalized phonons. We reveal that second sound can be attributed to the maximum group velocity of bending optical oscillations of carbon structures, and the hydrodynamic effects disappear for T > 200K, being replaced by diffusive dynamics of thermal waves. Our numerical results suggest that the velocity of second sound in such low-dimensional structures is about 6 km/s, and the hydrodynamic effects are manifested stronger in carbon nanotubes rather than in carbon nanoribbons.

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Section: Discussionmentioning

confidence: 99%

Section: Relaxation Of a Periodic Thermal Latticementioning

confidence: 99%

Section: Comparison With Classical Molecular Dynamicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling of second sound in carbon nanostructures

Savin,

Kivshar

2022

Preprint

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“…This seminal work sets off an upsurge of theoretical and experimental research on phonon hydrodynamics phenomena in low-dimensional or multi-layer materials, such as the drifting second sound [19][20][21] , heat vortices 22 and phonon Poiseuille flow with parabolic distribution of heat flux [23][24][25] . The drifting second sound, more specifically, the temperature wave signal was measured experimentally by the transient thermal grating method in high-quality graphite samples at 100 − 200 K 26,27 . Until now, the parabolic distribution of heat flux or the heat vortices has never been measured directly in experiments.…”

Section: Introductionmentioning

confidence: 99%

Transient hydrodynamic phonon transport in two-dimensional disk geometry

Zhang¹,

Wu²

2022

Preprint

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This paper is a continuation of our work on the transient hydrodynamic phonon transport from three-dimensional to two-dimensional materials. In the previous work [Zhang et al., Int. J. Heat Mass Transfer 181, 121847 (2021)], a transient heat conduction phenomenon proving the existence and uniqueness of hydrodynamic phonon transport in three-dimensional materials was found, namely, using a heating laser pulse to heat the materials under the environment temperature, after the heating laser is removed, the transient temperature could be lower than the environment temperature. Whether this phenomenon could appear in two-dimensional materials needs further study. In this paper, the transient heat conduction in two-dimensional disk geometry is studied based on the phonon Boltzmann transport equation (BTE). Our results show that this phenomenon could appear in two-dimensional disk geometry and only appear in the hydrodynamic regime. In addition, the possibility of this phenomenon observed by experiments is theoretically discussed by using the experimental parameters as the input of the phonon BTE. Results show that this phenomenon could appear in a single-layer suspended graphene disk with diameter 7 µm in the temperature range of 50 − 150 K. The present work could provide theoretical guidance for the future experimental proof of hydrodynamic phonon transport in two-dimensional materials.

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Ballistic Thermal Transport at Sub‐10 nm Laser‐Induced Hot Spots in GaN Crystal

et al. 2022

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Ballistic thermal transport at nanoscale hotspots will greatly reduce the performance of a Gallium nitride (GaN) device when its characteristic length reaches the nanometer scale. In this work, the authors develop a tip‐enhanced Raman thermometry approach to study ballistic thermal transport within the range of 10 nm in GaN, simultaneously achieving laser heating and measuring the local temperature. The Raman results show that the temperature increase from an Au‐coated tip‐focused hotspot up to two times higher (40 K) than that in a bare tip‐focused region (20 K). To further investigate the possible mechanisms behind this temperature difference, the authors perform electromagnetic simulations to generate a highly focused heating field, and observe a highly localized optical penetration, within a range of 10 nm. The phonon mean free path (MFP) of the GaN substrate can thus be determined by comparing the numerical simulation results with the experimentally measured temperature increase which is in good agreement with the average MFP weighted by the mode‐specific thermal conductivity, as calculated from first‐principles simulations. The results demonstrate that the phonon MFP of a material can be rapidly predicted through a combination of experiments and simulations, which can find wide application in the thermal management of GaN‐based electronics.

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Observation of second sound in graphite over 200 K

Cited by 62 publications

References 57 publications

Modeling of second sound in carbon nanostructures

Modeling of second sound in carbon nanostructures

Transient hydrodynamic phonon transport in two-dimensional disk geometry

Ballistic Thermal Transport at Sub‐10 nm Laser‐Induced Hot Spots in GaN Crystal

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