Measurements of Non-classical Rotational Inertia of Solid 4He at Two Frequencies

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

doi:10.1007/s10909-007-9543-2

Cited by 20 publications

(16 citation statements)

References 12 publications

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“…Subsequently measured temperature dependence of the frequency shifts of the two modes are similar to those shown in Fig. 2 (6), (blue) squares (12), and (orange) stars (25). Results shown for the 25 ppm sample include temperatures up to 2.5 (1.6) K for the first (second) mode not displayed in Fig.…”

Section: Plotting In This Manner Reveals Similarity and Dissimilaritysupporting

confidence: 71%

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Effects ofHe3impurity on solidHe4studied by compo

et al. 2011

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Frequency shifts and dissipation of a compound torsional oscillator induced by solid 4 He samples containing 3 He impurity concentrations (x3 = 0.3, 3, 6, 12 and 25 in units of 10 −6 ) have been measured at two resonant mode frequencies (f1 = 493 and f2 = 1164 Hz) at temperatures (T ) between 0.02 and 1.1 K. The fractional frequency shifts of the f1 mode were much smaller than those of the f2 mode. The observed frequency shifts continued to decrease as T was increased above 0.3 K, and the conventional non-classical rotation inertia fraction was not well defined in all samples with x3 ≥ 3 ppm. Temperatures where peaks in dissipation of the f2 mode occurred were higher than those of the f1 mode in all samples. The peak dissipation magnitudes of the f1 mode was greater than those of the f2 mode in all samples. The activation energy and the characteristic time (τ0) were extracted for each sample from an Arrhenius plot between mode frequencies and inverse peak temperatures. The average activation energy among all samples was 430 mK, and τ0 ranged from 2×10 −7 s to 5×10 −5 s in samples with x3 = 0.3 to 25 ppm. The characteristic time increased with increasing x3. Observed temperature dependence of dissipation were consistent with those expected from a simple Debye relaxation model if the dissipation peak magnitude was separately adjusted for each mode. Observed frequency shifts were greater than those expected from the model. The discrepancies between the observed and the model frequency shifts increased at the higher frequency mode.

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Section: Plotting In This Manner Reveals Similarity and Dissimilaritysupporting

confidence: 71%

“…1 was modified from the earlier one 10,25 and has two torsion rods (a, b) each with diameter 1.9 mm and length 15 mm, and two interconnected masses. The flange above the upper rod (a) is rigidly attached to a large copper vibration isolation block in good thermal contact with the mixing chamber of a dilution refrigerator.…”

Section: Methodsmentioning

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Effects ofHe3impurity on solidHe4studied by compo

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“…Operation of double compound oscillator has been described previously [6,35]. The sample container attached to the TO is a thin annulus (10.0 mm outer diameter, 9.6 inner diameter, 8.0 mm height).…”

Section: Apparatus and Proceduresmentioning

confidence: 99%

Aging of solid 4He under torsional oscillation at low temperatures

Gumann

Kojima

2013

Low Temperature Physics

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Observations have been made to reveal unusual aging behavior in solid 4 He samples contained in a torsional oscillator. Oscillation of samples is initiated at a given oscillator drive amplitude near 100 mK. After the samples are cooled to a measurement temperature, they are "aged" for a waiting time, t w , between 15 min and 25 h. The drive amplitude is then halved and subsequent variation in the oscillator response amplitude, A(t), and frequency are monitored as time t elapses. When the measurement temperature is lower than T s = 40 mK, A(t) shows unusual behavior: A(t) initially undershoots to less than half of the original value, partially recovers exponentially and eventually continues to increase logarithmically. The amount of undershoot, partial recovery magnitude and the rate of logarithmic increase all show aging effect with logarithmic dependence on t w . When the measurement temperature is greater than T s , the above unusual behavior in A(t) disappears.

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“…[62][63][64][65] TO experiments have also been replicated under a number of different conditions in order to extract a greater amount of information. 61,[65][66][67][68][69][70][71] At this point it is important to summarize the findings from the set of experimental results obtained by the TO technique.…”

Section: Special Topicsmentioning

confidence: 99%

Solid ⁴He and the Supersolid Phase: from Theoretical Speculation to the Discovery of a New State of Matter? –A Review of the Past and Present Status of Research–

Galli

Reatto

2008

J. Phys. Soc. Jpn.

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The possibility of a supersolid state of matter, i.e., a crystalline solid exhibiting superfluid properties, first appeared in theoretical studies about forty years ago. After a long period of little interest due to the lack of experimental evidence, it has attracted strong experimental and theoretical attention in the last few years since Kim and Chan (Penn State, U.S.A.) reported evidence for nonclassical rotational inertia effects, a typical signature of superfluidity, in samples of solid 4 He. Since this ''first observation'', other experimental groups have observed such effects in the response to the rotation of samples of crystalline helium, and it has become clear that the response of the solid is extremely sensitive to growth conditions, annealing processes, and 3 He impurities. A peak in the specific heat in the same range of temperatures has been reported as well as anomalies in the elastic behaviour of solid 4 He with a strong resemblance to the phenomena revealed by torsional oscillator experiments. Very recently, the observation of unusual mass transport in hcp solid 4 He has also been reported, suggesting superflow. From the theoretical point of view, powerful simulation methods have been used to study solid 4 He, but the interpretation of the data is still rather difficult; dealing with the question of supersolidity means that one has to face not only the problem of the coexistence of quantum coherence phenomena and crystalline order, exploring the realm of spontaneous symmetry breaking and quantum field theory, but also the problem of the role of disorder, i.e., how defects, such as vacancies, impurities, dislocations, and grain boundaries, participate in the phase transition mechanism.

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Measurements of Non-classical Rotational Inertia of Solid 4He at Two Frequencies

Cited by 20 publications

References 12 publications

Effects ofHe3impurity on solidHe4studied by compo

Effects ofHe3impurity on solidHe4studied by compo

Aging of solid 4He under torsional oscillation at low temperatures

Solid ⁴He and the Supersolid Phase: from Theoretical Speculation to the Discovery of a New State of Matter? –A Review of the Past and Present Status of Research–

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Measurements of Non-classical Rotational Inertia of Solid 4He at Two Frequencies

Cited by 20 publications

References 12 publications

Effects ofHe3impurity on solidHe4studied by compo

Effects ofHe3impurity on solidHe4studied by compo

Aging of solid 4He under torsional oscillation at low temperatures

Solid 4He and the Supersolid Phase: from Theoretical Speculation to the Discovery of a New State of Matter? –A Review of the Past and Present Status of Research–

Contact Info

Product

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Solid ⁴He and the Supersolid Phase: from Theoretical Speculation to the Discovery of a New State of Matter? –A Review of the Past and Present Status of Research–