Related papers: Evidence for Supersolidity in Bulk Solid $^4$He
Solid He4 is viewed as a nearly perfect Debye solid. Yet, recent calorimetry indicates that its low-temperature specific heat has both cubic and linear contributions. These features appear in the same temperature range ($T \sim 200$ mK)…
We report studies, using a two mode torsional oscillator, of the putative supersolid signature in polycrystalline 4He. Measurements at two frequencies enable us to eliminate the viscoelastic contribution to the signature, and other…
In recent torsional oscillator experiments by Kim and Chan (KC), a decrease of rotational inertia has been observed in solid 4He in porous materials and in a bulk annular channel. This observation strongly suggests the existence of…
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,…
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…
In pure superfluid $^3$He-B at ultra-low temperatures, quartz tuning fork oscillator response is expected to saturate when the dissipation caused by the superfluid medium becomes substantially smaller than the internal dissipation of the…
In the experiment on superfluid transport in solid He4 [PRL {\bf 100}, 235301 (2008)], Ray and Hallock observed an {\it anomalously large isochoric compressibility}: the supersolid samples demonstrated a significant and apparently spatially…
Although both vacancies and interstitial have relatively high activation energies in the normal solid, we propose that a lower energy bound state of a vacancy and an interstitial may facilitate vacancy condensation to give supersolidity in…
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…
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…
Fundamental considerations predict that macroscopic quantum systems such as superfluids and the electrons in superconductors will exhibit oscillatory motion when pushed through a small constriction. Here we report the observation of these…
We have studied natural purity $^{4}$He single crystals and polycrystals between 10 and 600 mK using a torsional oscillator with a 2 cm$^{3}$ rigid cell made of sapphire with a smooth geometry. As the temperature was lowered, we observed…
In these torsional oscillator experiments the samples of solid $^4$He were characterized by measuring their thermal conducitvity. Polycrystalline samples of helium of either high isotopic purity or natural concentration of $^3$He were grown…
We have used a torsional oscillator with square cross section and a resonance frequency of 185 Hz to confirm the nonclassical rotational inertia (NCRI) discovered by Kim and Chan\cite{1,2}. We have also found a strong correlation between…
The non-classical rotational inertia fraction of the identical cylindrical solid $^4$He below 300 mK is studied at 496 and 1173 Hz by a double resonance torsional oscillator. Below 35 mK, the fraction is the same at sufficiently low rim…
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…
The shear modulus of solid $^4$He exhibits an anomalous change of order 10%[1, 2] at low temperatures that is qualitatively similar to the much smaller frequency change in torsional oscillator experiments. We propose that in solid $^4$He…
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…
The ground state of solid $^4$He is studied using the diffusion Monte Carlo method and a new trial wave function able to describe the supersolid. The new wave function is symmetric under the exchange of particles and reproduces the…
In this work we investigate the quantum nature of bcc $^{4}$He. We show that it is a solid phase with an Off-Diagonal Long Range Order of coherently oscillating local electric dipole moments. These dipoles arise from the correlated…