Low-temperature shear modulus changes in solid 4He and connection to supersolidity

  title={Low-temperature shear modulus changes in solid 4He and connection to supersolidity},
  author={James Day and John Beamish},
Superfluidity—liquid flow without friction—is familiar in helium. The first evidence for ‘supersolidity’, its analogue in quantum solids, came from torsional oscillator measurements involving 4He. At temperatures below 200 mK, the torsional oscillator frequencies increased, suggesting that some of the solid decoupled from the oscillator. This behaviour has been replicated by several groups, but solid 4He does not respond to pressure differences, and persistent currents and other signatures of… 

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Recent measurements have shown that solid He4 can decouple from a torsional oscillator below 200mK, and defects appear to be crucial to this behavior. Helium’s shear modulus increases in the same

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Evidence for a Superglass State in Solid 4He

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The recently discovered shear modulus anomaly in solid 4He bears a strong similarity to the phenomenon of supersolidity in solid 4He and can lead to the period shift and dissipative signals in



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A decrease in the rotational period observed in torsional oscillator measurements was recently taken as a possible indication of a supersolid state of helium. We reexamine this interpretation and

Observation of Non-Classical Rotational Inertia in Bulk Solid 4He

Abstract In recent torsional oscillator experiments by Kim and Chan (KC), a decrease of rotational inertia has been observed in solid 4He in porous materials (Kim, E., Chan, M.H.W. in Nature 427:225,

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A piezoelectrically driven diaphragm is used to study the flow of solid helium through an array of capillaries, showing no indication of low temperature flow and placing stringent restrictions on supersolid flow in response to a pressure difference.

Two new vortex liquids

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The longitudinal sound velocity in hcp 4 He single crystals grown at 35.5 atm has been measured between 0.25 and 1.7 K at 10, 30, and 50 MHz. Above about 1 K, the change in the velocity is

Observation of classical rotational inertia and nonclassical supersolid signals in solid 4He below 250 mK.

The nonclassical rotational inertia signal is not a universal property of solid 4He but can be eliminated through an annealing of the solid helium sample, which has important implications for the understanding of the supersolid state.

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