Simultaneous Measurements of the Torsional Oscillator Anomaly and Thermal Conductivity in 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>

Zmeev, D. E.; Golov, A. I.

doi:10.1103/physrevlett.107.065302

Cited by 19 publications

(19 citation statements)

References 24 publications

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“…Therefore, it seems that polycrystallinity is the cause of the difference in decoupled mass. We mention that the decoupled mass fraction with polycrystals is very similar to the one seen in low temperature experiments using 4 He of commercial purity 1,2,3,4,5,6,7 .…”

Section: Resultssupporting

confidence: 49%

BCC vs. HCP—The Effect of Crystal Symmetry on the High Temperature Mobility of Solid 4He

Eyal

Polturak²

2012

J Low Temp Phys

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We report results of torsional oscillator (TO) experiments on solid 4 He at temperatures above 1K. We have previously found that single crystals, once disordered, show some mobility (decoupled mass) even at these rather high temperatures. The decoupled mass fraction with single crystals is typically 20-30%. In the present work we performed similar measurements on polycrystalline solid samples. The decoupled mass with polycrystals is much smaller, ∼ 1%, similar to what is observed by other groups. In particular, we compared the properties of samples grown with the TO's rotation axis at different orientations with respect to gravity. We found that the decoupled mass fraction of bcc samples is independent of the angle between the rotation axis and gravity. In contrast, hcp samples showed a significant difference in the fraction of decoupled mass as the angle between the rotation axis and gravity was varied between zero and 85 degrees. Dislocation dynamics in the solid offers one possible explanation of this anisotropy.

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Section: Resultssupporting

confidence: 49%

BCC vs. HCP—The Effect of Crystal Symmetry on the High Temperature Mobility of Solid 4He

Eyal

Polturak²

2012

J Low Temp Phys

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“…missing, rotational inertia (NCRI) in solid helium at low temperature has been reported in torsional oscillator (TO) experiments in at least 9 different laboratories. [1][2][3][4][5][6][7][8][9][10][11] The solid helium samples inside the TOs have dimensions of at most five centimeters. If solid helium at low temperature is a 'standard' superfluid, like superconductivity and superfluidity in liquid helium, one would expect the observation of NCRI will not be limited to centimeter length scales.…”

mentioning

confidence: 99%

Probing phase coherence in solid helium using torsional oscillators of different path lengths

et al. 2012

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Long range phase coherence is a critical signature of macroscopic quantum phenomena. To date, non-classical rotational inertia (NCRI) of solid helium has been reported only in samples with physical dimension of at most five centimeters. We have investigated solid helium in longer path length torsional oscillators. Samples of length ranging from 6 to 100 cm were grown inside toroids and in self-connected long capillaries. NCRI of 4 × 10 −5 and 3 × 10 −5 were found in cells with path length of 6 and 9 cm. In cells with path length of 30 and 100 cm, NCRI if exists, is less than 7 × 10 −5 and 4 × 10 −5 respectively.

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“…We argue that, in our experimental set-up, the TO and thermal conductivity probe solid helium at different locations. The absence of correlations between the TO frequency shifts r f Δ and phonon mean free path , that was reported previously [18,19] (see Fig. 6) might thus not be too surprising.…”

Section: Discussionmentioning

confidence: 79%

“…In this context, the mean free path of thermal phonons becomes the measure of the presence of dislocations as seen by high-frequency (10 9 -10 10 Hz) oscillations of solid helium. Experimental details and some results were published in [18,19].…”

Section: Solid Heliummentioning

confidence: 99%

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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Simultaneous Measurements of the Torsional Oscillator Anomaly and Thermal Conductivity in SolidHe4

Cited by 19 publications

References 24 publications

BCC vs. HCP—The Effect of Crystal Symmetry on the High Temperature Mobility of Solid 4He

BCC vs. HCP—The Effect of Crystal Symmetry on the High Temperature Mobility of Solid 4He

Probing phase coherence in solid helium using torsional oscillators of different path lengths

Thermal conductivity and torsional oscillations of solid 4He

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