Dislocations in a quantum crystal

Balibar, S.; Beamish, John; Fefferman, Andrew; Haziot, Ariel; Rojas, Xavier; Souris, Fabien

doi:10.1016/j.crhy.2015.12.015

Cited by 14 publications

(49 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Increasing the stress on the samples also results in tearing the 3 He atoms away from the dislocation lines, hence creating an apparent velocity dependence of the signals. For a comprehensive discussion of the rather complex problem of the motion of dislocation lines in solid 4 He, see the review article by Balibar et al (29). In our work, the frequency range of the multiple frequency TOs is restricted to a range between 600-2,500 Hz, much smaller than that shown in Fig.…”

Section: Significancementioning

confidence: 77%

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

Eyal

Talanov

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

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 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 expected to be independent of frequency. We find in our measurements that as the temperature is lowered below 0.2 K, a clear frequency-dependent contribution to the period shift arising from changes in the 4 He elastic properties is always present. For all of the cells reported in this paper, however, there is always an additional small frequency-independent contribution to the total period shift, such as would be expected in the case of a transition to a supersolid state.supersolid | helium 4 | torsional oscillators T he idea of the existence of a supersolid state, a new phase of matter, stimulated a large number of experimental and theoretical works over the past 45 y, especially in the past decade. Such a state is assumed to present properties of superflow in a, most likely bosonic, solid. It was first suggested to exist based on theoretical grounds by Andreev and Lifshitz (1), Chester (2), and Leggett (3) in the late 1960s and early 1970s. Because 4 He exhibits superfluidity, and because it is a bosonic material with a low mass and weak interatomic interactions, solid 4 He was a natural candidate in the search for supersolidity.Torsional oscillators (TOs) have been the chief instrument in the investigation of this possible supersolid state of 4 He. The use of TOs in the search for this state follows a suggestion by Leggett in 1970 (3) that the appearance of the supersolid state would result in an anomalous superfluid-like decoupling of a portion of the moment of inertia of the solid 4 He sample from the TO in a manner analogous to the decoupling of the superfluid fraction of liquid 4 He as observed by Andronikashvili (4) in his early TO experiments. Such a reduction of the moment of inertia upon entering the superfluid or supersolid state was termed by Leggett to be a nonclassical rotational inertia (NCRI). The NCRI reduction in the moment of inertia is then expected to begin to increase with decreasing temperature below an onset temperature and lead to an observable decrease in the period of a TO containing a supersolid sample.The first attempt to observe ...

show abstract

Section: Significancementioning

confidence: 77%

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

Eyal

Talanov

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Several nuclear magnetic resonance studies have shown that at low temperatures 3 He atoms in solid 4 He behave as quantum quasi-particles that can move through the lattice at velocities as high as ∼ 1 mm/s (Allen, Richards, and Schratter, 1982;Kim et al, 2013), that is, significantly higher than 45 µm/s. It has been argued then that near the dislocation the mobility of isotopic impurities could be reduced considerably by the existing local strain (Balibar et al, 2016); however, there is not quantitative evidence showing that such a huge variation of about three orders of magnitude in the mobility of 3 He impurities could be actually possible. Clearly, a microscopic understanding of what are the interactions between dislocations and quantum isotopic impurities, and the factors that can affect the mobility of the latter, is necessary.…”

Section: B Dislocationsmentioning

confidence: 99%

“…In a series of compelling experimental works, Balibar, Beamish and collaborators have characterised the energy, structural, and dynamic properties of dislocations in solid 4 He (for a recent review, see Balibar et al, 2016). The usual experimental setup in those studies consists in a measurement cell supplied with two piezoelectric shear plates that are placed facing each to the other with a separation of few millimeters; the narrow gap that is formed between the transducers then is filled with a crystal that is oriented in a particular direction.…”

Section: B Dislocationsmentioning

confidence: 99%

“…In the context of solid 4 He, "high temperatures" are considered to be T ≥ 0.3 K (Balibar et al, 2016). In the equations above α and B represent two thermal phonon damping parameters (which in solid 4 He are equal to 0.019 and 905 s·m −2 K −3 , respectively, see Souris et al, 2014a), Λ the density of dislocation lines per surface unit, L a typical length between nodes in the dislocation network, and ω the frequency of the alternating strain field.…”

Section: B Dislocationsmentioning

confidence: 99%

See 1 more Smart Citation

Simulation and understanding of atomic and molecular quantum crystals

2017

View full text Add to dashboard Cite

Quantum crystals abound in the whole range of solid-state species. Below a certain threshold temperature the physical behavior of rare gases ( 4 He and Ne), molecular solids (H 2 and CH 4 ), and some ionic (LiH), covalent (graphite), and metallic (Li) crystals can be only explained in terms of quantum nuclear effects (QNE). A detailed comprehension of the nature of quantum solids is critical for achieving progress in a number of fundamental and applied scientific fields like, for instance, planetary sciences, hydrogen storage, nuclear energy, quantum computing, and nanoelectronics. This review describes the current physical understanding of quantum crystals formed by atoms and small molecules, as well as the wide palette of simulation techniques that are used to investigate them. Relevant aspects in these materials such as phase transformations, structural properties, elasticity, crystalline defects and the effects of reduced dimensionality, are discussed thoroughly. An introduction to quantum Monte Carlo techniques, which in the present context are the simulation methods of choice, and other quantum simulation approaches (e. g., path-integral molecular dynamics and quantum thermal baths) is provided. The overarching objective of this article is twofold. First, to clarify in which crystals and physical situations the disregard of QNE may incur in important bias and erroneous interpretations. And second, to promote the study and appreciation of QNE, a topic that traditionally has been treated in the context of condensed matter physics, within the broad and interdisciplinary areas of materials science.

show abstract

“…Supersolidity regarded from this point of view is inevitably connected to the question whether solid helium is a quantum supersolid (for a recent review see Ref. [12]). …”

Section: Introductionmentioning

confidence: 99%

Optical lattices as a tool to study defect-induced superfluidity

et al. 2017

View full text Add to dashboard Cite

We study the superfluid response, the energetic and structural properties of a one-dimensional ultracold Bose gas in an optical lattice of arbitrary strength. We use the Bose-Fermi mapping in the limit of infinitely large repulsive interaction and the diffusion Monte Carlo method in the case of finite interaction. For slightly incommensurate fillings we find a superfluid behavior which is discussed in terms of vacancies and interstitials. It is shown that both the excitation spectrum and static structure factor are different for the cases of microscopic and macroscopic fractions of defects. This system provides a extremely well-controlled model for studying defect-induced superfluidity.

show abstract

Dislocations in a quantum crystal

Cited by 14 publications

References 28 publications

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

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

Simulation and understanding of atomic and molecular quantum crystals

Optical lattices as a tool to study defect-induced superfluidity

Contact Info

Product

Resources

About

Dislocations in a quantum crystal

Cited by 14 publications

References 28 publications

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

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

Simulation and understanding of atomic and molecular quantum crystals

Optical lattices as a tool to study defect-induced superfluidity

Contact Info

Product

Resources

About

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

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