Quantum Solid properties, the Supersolid state, and the Vortex State (original) (raw)

Journal de Physique, 1989

2014 L'existence d'une superfluidité pour un solide de bosons a été proposée par plusieurs théoriciens. Aucune expérience ne l'a jusqu'à présent révélée. Nous présentons un argument qui nous a incités à explorer la gamme de température 1 mK-20 mK. Nous avons tenté de détecter un courant de masse à travers du 4He solide à 4 mK. L'absence d'effet abaisse encore la borne supérieure pour la température de superfluidité de ce solide. Abstract. 2014 Theoreticians agree that superfluidity can exist in a Bose solid. The experiments to detect such an effect have failed up to now. We present here an argument that justifies the exploration of the 1 mK-20 mK temperature range. We have carried out an experiment to detect a mass flow through the solid 4He down to 4 mK. No anomalous effect occurred, and this result therefore further reduces the upper limit for the occurrence of superfluidity in solid 4He to below 4 mK. 1bme 50 N° 15 1er AOUT 1989

Torsional oscillators and the entropy dilemma of putative supersolid 4 He

Journal of Physics: Conference Series, 2009

Solid 4 He is viewed as a nearly perfect Debye solid. Yet, recent calorimetry measurements by the PSU group (J. Low Temp. Phys. 138, 853 (2005) and Nature 449, 1025 ) indicate that at low temperatures the specific heat has both cubic and linear contributions. These features appear in the same temperature range where measurements of the torsional oscillator period suggest a supersolid transition. We analyze the specific heat and compare the measured with the estimated entropy for a proposed supersolid transition with 1% superfluid fraction and find that the observed entropy is too small. We suggest that the low-temperature linear term in the specific heat is due to a glassy state that develops at low temperatures and is caused by a distribution of tunneling systems in the crystal. We propose that dislocation related defects produce those tunneling systems. Further, we argue that the reported putative mass decoupling, that means an increase in the oscillator frequency, is consistent with a glass-like transition. The glass scenario offers an alternative interpretation of the torsional oscillator experiments in contrast to the supersolid scenario of nonclassical rotational inertia.

A glassy counterpart to supersolids A Viewpoint on: Theory of the superglass phase

Glasses are liquids that have ceased to flow on experimentally measurable time scales. By constrast, superfluids flow without any resistance. The existence of a phase characterized by simultaneous glassiness and superfluidity may seem like a clear contradiction. However, in a paper in Physical Review B, Giulio Biroli (Institut de Physique Théorique, France), Claudio Chamon (Boston University), and Francesco Zamponi (École Normale Supérieure, France) prove that this is not so [1] and illustrate theoretically the possibility of a "superglass" phase. This phase forms an intriguing amorphous counterpart to the "supersolid" phase [2, 3] that has seen a surge of interest in recent years . Within a "supersolid" phase, superfluidity can occur without disrupting crystalline order.

Supersolid state of matter

Physical review letters, 2005

We prove that the necessary condition for a solid to be also a superfluid is to have zero-point vacancies, or interstitial atoms, or both, as an integral part of the ground state. As a consequence, in the absence of symmetry between vacancies and interstitials, superfluidity has a zero probability to occur in commensurate solids which break continuous translation symmetry. We discuss recent 4He experiments by Kim and Chan in the context of this theorem, question its bulk supersolid interpretation, and offer an alternative explanation in terms of superfluid interfaces.

Vortex Dynamics in hcp Solid 4He

Journal of Low Temperature Physics, 2009

The peculiar features noted in (Penzev et al. in Phys. Rev. Lett. 101: 065301, 2008) we conjecture are evidence of a vortex fluid state in solid He. We suggest to analyze this state by means of the dynamics of quantized vortices, as used for the tangle of vortices in superfluid turbulence. We introduce parameters of the vortex tangle dynamics, e.g., relaxation time for the drift of lines in parallel to the torsional oscillation axis. We briefly discuss the transition from the supposed vortex fluid state into the supposed supersolid state (Shimizu et al. in Phys. Rev. Lett., arXiv:0903.1326).

Vortex-Loops and Solid Nucleation in Superfluid 4He and 3He

2002

We propose a new model for the nature of the nucleation of solid from the superfluid phases of 4 He and 3 He. Unique to the superfluid phases the solid nucleation involves an extremely fast solidification front. This results in a local release of pressure and a velocity field in the superfluid. The superfluid velocity in turn facilitates the nucleation of vortex-loops. The kinetic energy gain of this process balances the surface tension, as the solid surface is quickly covered by many vortexloops ("hairy snow-ball"). We show that this scenario gives good agreement with experiments on heterogeneous nucleation, which differ with the classical theory of homogeneous nucleation by 8 orders of magnitude. We propose several experiments that could show the involvement of vortices with solid nucleation.

The role of defects in Supersolid Helium-4

Computer Simulation Studies in Condensed Matter Physics Xx, Csp-2007: Proceedings of the 20th Workshop, 2010

We seek an explanation for the observed non-classical rotational inertia in solid Helium-4. We study the activation energy for a single vacancy in an otherwise perfect crystal, which is huge and leads to the conclusion that there are no thermal vacancies in solid Helium-4 at the experimentally relevant temperatures. We also study grain boundaries and find that they can be mechanically stable when brought into contact with liquid, and can turn superfluid. Contact with recents experiments is made.

Search for supersolidity in solid 4He using multiple-mode torsional oscillators

Proceedings of the National Academy of Sciences of the United States of America, 2016

In 2004, Kim and Chan (KC) reported a decrease in the period of torsional oscillators (TO) containing samples of solid (4)He, as the temperature was lowered below 0.2 K [Kim E, Chan MHW (2004) Science 305(5692):1941-1944]. These unexpected results constituted the first experimental evidence that the long-predicted supersolid state of solid (4)He may exist in nature. The KC results were quickly confirmed in a number of other laboratories and created great excitement in the low-temperature condensed-matter community. Since that time, however, it has become clear that the period shifts seen in the early experiments can in large part be explained by an increase in the shear modulus of the (4)He solid identified by Day and Beamish [Day J, Beamish J (2007) Nature 450(7171):853-856]. Using multiple-frequency torsional oscillators, we can separate frequency-dependent period shifts arising from changes in the elastic properties of the solid (4)He from possible supersolid signals, which are e...

Observation of superfluid components in solid ^4He

Neutron scattering demonstrated that localized superfluid components exist at high pressure within solid helium in aerogel [1]. Two sharp phonon-roton spectra are clearly distinguishable from modes in bulk superfluid helium. These roton excitations exhibit different roton gap parameters than the roton observed in the bulk fluid at freezing pressure. One of the roton modes disappears after annealing. Comparison with theoretical calculations suggests that the model that reproduces the observed data best is that of superfluid double layers within the solid and at the helium-substrate interface. The elastic scattering evidenced in addition to the hcp phase also the bcc-phase. both consisting of a small crystallites as a consequence of the confinement. The structural aspect of coexisting hcp and bcc phases in the aerogel matrix seems to be important for the creation of the localized superfluid components.[4pt] [1] H. Lauter, E. Krotscheck, E. Kats, A. V. Puchkov, V. V. Lauter, V. Apaja, ...