New Dissipation Relaxation Phenomenon in Oscillating 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; Keiderling, Michael; Kojima, H.

doi:10.1103/physrevlett.100.215303

Cited by 28 publications

(26 citation statements)

References 21 publications

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“…This is shorter than that of the empty cell, indicating that there is an extra dissipative process in the solid sample that provides damping to the torsional oscillator. We find that τ increases for T < 100 mK, which is consistent with the literature 10,19 . An increase in τ , that is, a slowing down of the internal relaxation of 4 He, can be explained by the progressive freezing out of excitations present in the solid 10,20 .…”

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confidence: 92%

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Observation of hidden phases in supersolid 4He

Choi

Kwon

et al. 2010

Nature Phys

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Liquid helium becomes a superfluid and flows with zero viscosity at low temperatures. Superfluidity is manifested by a failure to rotate, as its mass is decoupled from the rotation of the containing cell. Supersolid helium should show similar behaviour; apparent rotational inertia decreases when the solid helium is set into torsional oscillation below 200 mK (refs 1,2) Unlike a typical superfluid, the non-classical rotational inertia fraction (NCRIF) has been found to be partially hysteretic 8 . The low-temperature (T <∼ 20 mK) value of NCRIF for a sample was smaller when cooled down in a high-velocity field (HVF), versus that obtained at low speeds. On reducing the velocity at the lowest temperature, the NCRIF recovered the unsuppressed value. However, subsequent increases in the velocity did not result in any suppression of the NCRIF up to at least 800 µm s −1 . This hysteresis was observed only below about 40 mK. Slow warming and cooling cycles (all below 65 mK) following the above type of velocity sweeps have revealed that the NCRIF can be multivalued at the lowest temperatures 9 . The two research groups involved have described these findings in terms of the pinning of low-temperature excitations (such as dislocations and/or vortices) in solid 4 He. Here we examine the phenomena systematically by measuring the dynamic response of a torsional oscillator containing a bulk 4 He sample at a pressure of 40 bar. The sample was grown using the blocked capillary method. The torsional oscillator has an open volume of 1.92 cm 3 in a cylindrical form, with a 13 mm diameter and a height of 14.5 mm. The surface-area to volume (S/V ) ratio is 4.46 cm −1 . The empty cell has a resonant period of 1.328 ms and a mechanical quality factor of 2×10 6 at 4.2 K. Two procedures were used to reach a fixed temperature and rim velocity, both of which represent a different history. The first is a typical method from previous studies. After setting the driving voltage at 500 mK, the torsional oscillator was cooled to the base temperature of 23 mK. After equilibration at the lowest temperature, a slow warming scan was carried out. We will refer to this cooling procedure and the corresponding NCRIF as HVF cooling and HVF NCRIF, respectively. As the rim velocity v R of the torsional oscillator is temperature dependent for a constant driving voltage, we consistently denote each data set by the value of v R recorded at 23 mK.The second procedure was as follows. At 500 mK, the driving voltage was set to a low value such that v R at 23 mK is less than

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confidence: 92%

“…Temperature variation in this region then creates a mixed state between the weakly pinned and HVF-cooled states, resulting in a multivalued NCRIF. Comparison with previous measurements [8][9][10]19 reveals that despite the variation in the exact values of velocity and temperature, the general features of the phase diagram seem to be universal.…”

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confidence: 53%

Observation of hidden phases in supersolid 4He

Choi

Kwon

et al. 2010

Nature Phys

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“…They found no "overshoot" response in agreement with our [24] earlier work, but they observed a logarithmic time dependence in contrast to ours. It is known [6] that the direction of change in the drive amplitude strongly affects the TO response.…”

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confidence: 91%

“…In similar experiments as by Aoki et al [24], Choi et al [46] measured long time TO response after increases in drive amplitude. They found no "overshoot" response in agreement with our [24] earlier work, but they observed a logarithmic time dependence in contrast to ours.…”

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confidence: 68%

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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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Deformation kinetics within cylindrical micropores of glassy solid 4He at very low temperatures

Liu

Qin

2009

Ann. Phys.

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67.25.dr, 83.60.St, 83.60.Rs, 83.50.Lh The deformation kinetics for glassy solid helium confined in microscopic domain at very low temperature regime was investigated using a transition-rate-state dependent model considering the shear thinning behavior which means, once material being subjected to high shear rates, the viscosity diminishes with increasing shear rate. The preliminary results show that there might be nearly frictionless fields for rate of deformation due to the almost vanishing shear stress in micropores at very low temperature regime subjected to some surface conditions: The relatively larger roughness (compared to the macroscopic domain) inside micropores and the slip. As the pore size decreases, the surface-to-volume ratio increases and therefore, surface roughness will greatly affect the deformation kinetics in micropores. By using the boundary perturbation method, we obtained a class of temperature and activation energy dependent fields for the deformation kinetics at low temperature regime with the presumed small wavy roughness distributed along the walls of an cylindrical micropore. The critical deformation kinetics of the glassy matter is dependent upon the temperature, activation energy, activation volume, orientation dependent and is proportional to the (referenced) shear rate, the slip length, the amplitude and the orientation of the wavy-roughness. Finally, we also discuss the quantitative similarity between our results with Ray and Hallock [Phys. Rev. Lett. 100, 235301 (2008)].

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New Dissipation Relaxation Phenomenon in Oscillating SolidHe4

Cited by 28 publications

References 21 publications

Observation of hidden phases in supersolid 4He

Observation of hidden phases in supersolid 4He

Aging of solid 4He under torsional oscillation at low temperatures

Deformation kinetics within cylindrical micropores of glassy solid 4He at very low temperatures

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