Related papers: Viscoelastic Behavior of Solid $^4$He
We report low temperature measurements of bulk solid $^4$He in a two-frequency compound torsional oscillator with both annular and open cylinder sample geometries. The oscillators were designed to suppress period shifts arising from all…
The excitement following the initial report of supersolid behavior for $^4$He embedded in porous Vycor glass has been tempered by the realization that many of the early supersolid observations were contaminated by effects arising from an…
The low temperature properties of solid $^4$He contained in porous Vycor glass have been investigated utilizing a two-mode compound torsional oscillator. At low temperatures, we find period shift signals for the solid similar to those…
We have carried out torsional oscillator experiments on solid $^4$He at temperatures between 1.3K and 1.9K. We discovered phenomena similar to those observed at temperatures below 0.2K, which currently are under debate regarding their…
Frequency shifts and dissipations of a compound torsional oscillator induced by solid $^4$He samples containing $^3$He impurity concentrations ($x_3$ = 0.3, 3, 6, 12 and 25 in units of 10$^{-6}$) have been measured at two resonant mode…
The discovery by Kim and Chan (KC) of an anomalous decrease in the period of torsional oscillators (TO) containing samples of solid $^4$He at temperatures below 0.2 K was initially interpreted as a superfluid-like decoupling of a fraction…
Torsional oscillator experiments involving solid $^{4}$He confined in the nanoscale pores of Vycor glass showed anomalous frequency changes at temperatures below 200 mK. These were initially attributed to decoupling of some of the helium's…
We describe the first observations on the time-dependent dissipation when the drive level of a torsional oscillator containing solid He-4 is abruptly changed. The relaxation of dissipation in solid He-4 shows rich dynamical behavior…
We have studied the thermal history of the resonant frequency of a torsional oscillator containing solid 4He. We find that the magnitude of the frequency shift that occurs below 100 mK is multivalued in the low temperature limit, with the…
A simple phenomenological model is developed for the recent torsional oscillator experiments on solid $^4$He. Within this model, for a homogeneous sample there is a specific quantitative relation between the change in the oscillator's…
Torsional oscillator experiments on solid 4He show frequency changes which suggest mass decoupling, but the onset is broad and is accompanied by a dissipation peak. We have measured the elastic shear modulus over a broad frequency range,…
We calculated the glassy response of solid He-4 to torsional oscillations assuming a phenomenological glass model. Making only a few assumptions about the distribution of glassy relaxation times in a small subsystem of otherwise rigid solid…
A torsional oscillator study of solid para-hydrogen has been carried out down to 20 mK in search for evidence of superfluidity. This work was inspired by the observation of the supersolid phase in solid He-4. We found evidence of a possible…
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 torsional oscillator experiments that are…
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 note that the decrease in the rotation…
The torsional oscillator is the chief instrument for investigating supersolidity in solid 4He. These oscillators can be sensitive to the elastic properties of the solid helium, which show anomalies over the same range of temperature in…
We report a study of the temperature and stress dependence of the friction associated with a relative motion of two masses of solid $^4$He in contact. The situation where "two masses" coupled only by friction exists emerges spontaneously…
Superfluidity, liquid flow without friction, is familiar in helium. The first evidence for "supersolidity", its analogue in quantum solids, came from recent torsional oscillator (TO) measurements involving 4-He. At temperatures below 200…
We report studies of solid helium contained inside a torsional oscillator, at temperatures between 1.07K and 1.87K. We grew single crystals inside the oscillator using commercially pure $^4$He and $^3$He-$^4$He mixtures containing 100 ppm…
The rigid double-torus torsional oscillator (TO) is constructed to reduce any elastic effects in-herent to complicate TO structures, allowing explicit probing for a genuine supersolid signature. We investigated the frequency- and…