Second Sound in NaF

Jackson, Howard E.; Walker, C. E.; McNelly, T.

doi:10.1103/physrevlett.25.26

Cited by 234 publications

(162 citation statements)

References 3 publications

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“…The group velocity, which largely depends on phonon frequency, can cause a significant broadening in a ballistic heat pulse. To take account of this effect, we suppose an experiment for observing second sound, similar to the past experiments for threedimensional materials 4,9,45,47 . Suppose we have a rectangular shape graphene sheet with a point heat source at the left edge and a point thermal sensor at the right edge, as illustrated in the inset of Fig.…”

Section: Methodsmentioning

confidence: 99%

“…1c,d. The pulse in the hydrodynamic regime is transmitted by many N-scatterings 4,9,44,45 , whereas the pulse in the diffusive regime is largely damped by R-scattering and cannot propagate. The transmission of a heat pulse can also be observed in ballistic transport, but the sample size is limited to below phonon mean free path.…”

Section: Displaced Distribution Functionmentioning

confidence: 99%

“…5) and for second sound the range is 10-20 K (ref. 9). The extremely stringent temperature conditions for hydrodynamic phonon transport are due to Umklapp scattering (hereafter U-scattering), which destroys the crystal momentum.…”

mentioning

confidence: 99%

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Hydrodynamic phonon transport in suspended graphene

et al. 2015

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Recent studies of thermal transport in nanomaterials have demonstrated the breakdown of Fourier's law through observations of ballistic transport. Despite its unique features, another instance of the breakdown of Fourier's law, hydrodynamic phonon transport, has drawn less attention because it has been observed only at extremely low temperatures and narrow temperature ranges in bulk materials. Here, we predict on the basis of first-principles calculations that the hydrodynamic phonon transport can occur in suspended graphene at significantly higher temperatures and wider temperature ranges than in bulk materials. The hydrodynamic transport is demonstrated through drift motion of phonons, phonon Poiseuille flow and second sound. The significant hydrodynamic phonon transport in graphene is associated with graphene's two-dimensional features. This work opens a new avenue for understanding and manipulating heat flow in two-dimensional materials.

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Section: Methodsmentioning

confidence: 99%

Section: Displaced Distribution Functionmentioning

confidence: 99%

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Hydrodynamic phonon transport in suspended graphene

et al. 2015

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“…The observation of the second sound in the crystal NaF is discussed (see [9]). The second sound in the NaF is observed at a temperature of about 15K [10]. The existence of second sound waves was also confirmed in the NaF (see [11] and [12]); the speed of the second sound waves is 1953.1m/S see [13].…”

Section: Introductionmentioning

confidence: 66%

Compatibility Conditions in Continua with Microstrusture

Murashkin

Стадник

2017

MATEC Web Conf.

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Abstract. The present study is devoted to the statement of compatibility conditions on propagating wave sur-faces of strong and weak discontinuities in thermoelastic continua with microstructure. The field formalism is used to study the problem. A natural density of thermoelastic action and the corresponding variational least action principle are stated for a varying domain. A special form of the first variation of the action is employed to obtain 4-covariant boundary conditions on the wave surfaces. These are given by jumps of the Piola-Kirchhoff stress 4-tensor and the energy-momentum tensor. Problems of propagation of weak discontinuities in type-II MPTE continua are considered. Geometrical and kinematical compatibility conditions are used to study possi-ble wave surfaces of weak discontinuities. It is shown that the surfaces of weak discontinuities can propagate without weak discontinuities of the temperature displacement.

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“…The second sound propagation as defined here in a dielectric solid is then a propagation of collective oscillation in phonon density. It has been observed in solid 4 He and 3 He [24][25][26], sodium fluoride [27][28][29] and bismuth [30].…”

Section: Heat Pulse and Second Sound Propagation In Normal Solidmentioning

confidence: 99%

Search for fourth sound propagation in supersolid He4

Aoki

Kojima

Lin

2008

Low Temperature Physics

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A systematic study was carried out to search for fourth sound propagation solid 4 He samples below 500 mK down to 40 mK between 25 and 56 bar using the techniques of heat pulse generator and titanium superconducting transition edge bolometer. If solid 4 He is endowed with superfluidity below 200 mK as indicated by recent torsional oscillator experiments, theories predict fourth sound propagation in such supersolid state. If found, fourth sound provides a convincing evidence for superfluidity and a new tool for studying the new phase. To search for a fourth sound-like mode, the response of the bolometers to heat pulses traveling through cylindrical samples of solids grown with different crystal qualities. Bolometers with increasing sensitivity were constructed. The heater generator amplitude was reduced to the sensitivity limit to search for any critical velocity effects. The fourth sound velocity is expected to vary as µ r r s / . Searches were made for signature in the bolometer response with such characteristic temperature dependence. The measured response signal has not so far revealed any signature of new propagating mode within the temperature excursion of 5 mK from the background signal shape. Possible reasons for this negative result are discussed. Prior to the fourth sound search, the temperature dependence of heat pulse propagation was studied as it transformed from «second sound» in the normal solid 4 He to the transverse ballistic phonon propagation. Our work extended the studies by Narayanamurti and Dynes [Phys. Rev. B12, 1731(1975] to higher pressures and to lower temperatures. The measured transverse ballistic phonon propagation velocity remained constant, within 0.3% scatter of data below 100 mK at all pressures and revealed no indication for an onset of supersolidity. The overall dynamic thermal response of solid to heat input was found to depend strongly on the sample preparation procedure.

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Second Sound in NaF

Abstract: Propagation of heat pulses in NaF has been studied to higher temperatures in a purer crystal than studied by McNelly et al. At the highest temperautres the second-sound velocity fails to level off at the theoretically predicted limiting value.

Cited by 234 publications

References 3 publications

Hydrodynamic phonon transport in suspended graphene

Hydrodynamic phonon transport in suspended graphene

Compatibility Conditions in Continua with Microstrusture

Search for fourth sound propagation in supersolid He4

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