Oscillation Frequency Dependence of Nonclassical Rotation Inertia of Solid<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi>He</mml:mi><mml:mprescripts /><mml:none /><mml:mn>4</mml:mn></mml:mmultiscripts></mml:math>

Aoki, Yuki; Graves, J. C.; Kojima, H.

doi:10.1103/physrevlett.99.015301

Cited by 175 publications

(424 citation statements)

References 15 publications

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“…It is clear that the data and the expected temperature dependence do not match. If the much smaller superfluid density measured in our own [44] torsional oscillator with a cylindrical cell is assumed, then the expected temperature dependence (see solid line) is well within the scatter and the data is not inconsistent with the expectation. Since the cylindrical geometry of our torsional oscillator is closer to the present heat pulse experiment chamber, it is likely that this superfluid density is more appropriate.…”

Section: Velocity Of Heat Pulse Propagationsupporting

confidence: 53%

“…The relation, if any, between the reduction in superfluid density as seen in critical velocity effects in the torsional oscillator experiments [5,44] and the excitation energy in our heat pulse generator is important to investigate. Kim and Chan [38] found that the measured superfluid fraction was dependent on the amplitudes of the solid 4 He velocity: the fraction was nearly constant up to about 10 mm/s and it decreased at amplitudes higher than this.…”

Section: Velocity Of Heat Pulse Propagationmentioning

confidence: 99%

“…7 indicate the times at which fourth sound signal is expected from Eq. (3) with the superfluid fraction being taken from our torsional oscillator experiment [44].…”

Section: Search For Fourth Sound In Solid 4 He Below 200 Mkmentioning

confidence: 99%

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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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Section: Velocity Of Heat Pulse Propagationsupporting

confidence: 53%

Section: Velocity Of Heat Pulse Propagationmentioning

confidence: 99%

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Search for fourth sound propagation in supersolid He4

Aoki

Kojima

Lin

2008

Low Temperature Physics

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“…With increasing the concentration of 3 He impurities, 3 , x from below 0.1 ppb to 10 ppm, * T systematically increases from ~ 20 to ~ 200 mK [12]. Increasing frequency of oscillations by a small amount resulted in an increase in * T [13]. The effect was the largest in the most disordered samples, but can be reduced upon annealing and was absent in perfect monocrystals.…”

Section: Solid Heliummentioning

confidence: 95%

Thermal conductivity and torsional oscillations of solid 4He

Brazhnikov

Zmeev

Golov

2012

Low Temperature Physics

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Polycrystalline samples of hcp 4 He of molar volume V m = 19.5 cm 3 with small amount of 3 He impurities were grown in an annular container by the blocked-capillary method. Three concentrations of 3 He, x 3 , were studied: isotopically purified 4 He with the estimated x 3 < 10 -10 , commercial 'well-grade' helium with x 3 ~ 3⋅10 -7 and a mixture with x 3 = 2.5⋅10 -6. Torsional oscillations at two frequencies, 132.5 and 853.6 Hz, and thermal conductivity were investigated before and after annealing. The solid helium under investigation was located not only in the annular container but also in the axial fill line inside two torsion rods and dummy bob of the doublefrequency torsional oscillator. The analysis of the frequency shifts upon loading with helium and changing temperatures of different parts of the oscillator suggests that the three techniques probe the properties of solid helium in three different locations: the two different torsion modes respond to the changes of the shear modulus of solid helium in either of the two torsion rods while the thermal conductivity probes the phonon mean free path in solid helium inside the annular container. The temperature and width of the torsional anomaly increase with increasing frequency and x 3 . The phonon mean free path increases with increasing x 3 . Annealing typically resulted in an increased phonon mean free path but often in little change in the torsional oscillator response. While the magnitude of the torsional anomaly and phonon mean free path can be very different in different samples, no correlation was found between them. PACS: 67.80.bd Superfluidity in solid 4 He, supersolid 4 He; 65.40.-b Thermal properties of crystalline solids.

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“…This, termed the nonclassical rotational inertia (NCRI), is the strongest evidence yet for the existence of a supersolid. While these experiments have been much reproduced [6][7][8][9], another line of experiment has been to focus on particular aspects of the helium sample, such as the annealing process or the measurement of the shear modulus, which might suggest another explanation for the apparent existence of the supersolid phase. The annealing process has been shown to dramatically reduce the superfluid fraction [10,11], while the shear modulus displays a similar dependence to the NCRI [12].…”

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confidence: 99%

Activated Nucleation of Vortices in a Dipole-Blockaded Supersolid Condensate

2012

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Oscillation Frequency Dependence of Nonclassical Rotation Inertia of SolidHe4

Cited by 175 publications

References 15 publications

Search for fourth sound propagation in supersolid He4

Search for fourth sound propagation in supersolid He4

Thermal conductivity and torsional oscillations of solid 4He

Activated Nucleation of Vortices in a Dipole-Blockaded Supersolid Condensate

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