Finite-size scaling of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mi>He</mml:mi><mml:none /><mml:none /><mml:mprescripts /><mml:none /><mml:mn>4</mml:mn></mml:mmultiscripts></mml:mrow></mml:math>at the superfluid transition

Gasparini, Francis M.; Kimball, Mark O.; Mooney, Kevin; Diaz-Avila, Manuel

doi:10.1103/revmodphys.80.1009

Cited by 98 publications

(189 citation statements)

References 188 publications

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“…The behaviour of the bulk ρ s /ρ is indicated as a solid line 26 . The superfluid onset for the uniform 48.3 nm film is consistent with the t c in other uniform films 14 . The smallest value in ρ s /ρ at the transition is also consistent with, but somewhat larger (∼20%) than, the expected Kosterlitz-Thouless (KT) jump 27,28 (indicated by the dashed-dotted horizontal line).…”

Section: Figure 1 | the Confinement Cellsupporting

confidence: 69%

“…2 we indicate with a vertical line the expected position of the specific-heat maximum for a 31.7 nm planar film without the influence of the boxes. This is well known from measurements over a wide range of film thickness 14 . The signature of the film's maximum in the present data is shifted, δt m,f ∼ = (0.5 ± 0.07) × 10 −3 warmer than expected, an indication of the influence of the already superfluid boxes on the heat-capacity maximum of the normal film.…”

Section: Figure 1 | the Confinement Cellmentioning

confidence: 72%

“…The inset shows an expanded view of the data in the region where the film orders. Here the vertical line indicates the expected temperature T m of the specific heat maximum if the film were not influenced by the presence of boxes 14 . This is obtained by a least-squares fit of the data for planar confinement 14 and yields t m (31.7 nm) = (1.90 ± 0.07) × 10 −3 .…”

Section: Figure 1 | the Confinement Cellmentioning

confidence: 99%

“…Similarly, below T λ , and up to x ∼ = 4.7, we can use 13 (3) from existing data 14 . The calculated heat capacity of a 1.22 µmol uniform film 31.7 nm thick is shown at the bottom of Fig.…”

Section: Figure 1 | the Confinement Cellmentioning

confidence: 99%

“…From this observation we conclude that the boxes and film, at least near t m,f , act as a collective, rather than separate, thermodynamic system. To see the full extent of this behaviour, we can subtract from the total heat capacity that of a 31.7 nm uniform film, which can be calculated using empirical scaling functions established for films in other studies 14 . Finitesize correlation-length scaling 18 predicts that the thermodynamic response of a finite system of small dimension L should be related to its behaviour in the thermodynamic limit by functions that depend on the variable L/ξ , or, equivalently, after introducing ξ = ξ 0 t −ν , the variable tl 1/ν with l ≡ L/ξ 0 , ξ 0 = 0.143 nm for 4 He and T > T λ .…”

Section: Figure 1 | the Confinement Cellmentioning

confidence: 99%

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Coupling and proximity effects in the superfluid transition in 4He dots

et al. 2010

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The superfluid transition in 4 He is associated with the onset of an order parameter that is a macroscopic wavefunction. This is similar to the onset of superconductivity in metals and alloys. Yet, some of the hallmark phenomena that are associated with wavefunctions, and are evident in superconductors, have not been identified in 4 He. Here we report proximity effects on the specific heat and superfluid density of a thin 4 He film in equilibrium with an array of larger boxes of 4 He. Comparison with previous data also enables us, by scaling, to deduce an excess specific heat associated with a collective behaviour of weakly coupled boxes. These effects should be relevant to the understanding of experiments where helium has been studied when confined in packed powders, porous materials or other inhomogeneous confinements, where proximity and collective effects must be present but not readily quantifiable 1,2 . Our work also forms a point of comparison and contrast with the case of superconductors 3,4 , and is relevant to studies of Josephson effects in superfluids, coupling effects in arrays of Bose-condensed atoms 5,6 , and magnetic systems where, because of chemical composition, two separate but interacting ordering transitions take place 7,8 .In the case of superconductors, coupling and proximity effects have been well understood for many years. The large correlationlength amplitude ξ 0 makes coupling between two superconductors easy to achieve. Weak links with dimensions of the order of ξ 0 , which can be a metal, an insulator or another superconductor, enable measurements of the familiar Josephson effects (see for instance ref. 9). With 4 He these effects are much more difficult to achieve because ξ 0 is of the order of interatomic dimensions. Furthermore, weak links and coupling between two regions of 4 He cannot be achieved through any material other than 4 He. We can, however, take advantage of the growth of the correlation length with temperature T and critical exponent ν, ξ = ξ 0 |1 − T /T λ | −ν ≡ ξ 0 t −ν near the transition temperature T λ and construct apertures whereby analogous Josephson effects can be realized 10,11 .We are unaware of any theory that describes the effects on thermodynamic properties of a 'grain' or dot of helium due to a coupling to another dot through a weak link, or, for that matter, how this coupling is affected by the geometry or 'strength' of this link. This question arose while attempting to verify finite-size scaling for zero-dimensional crossover 12 . We had measured the heat capacity of helium in arrays of (1 µm) 3 and (2 µm) 3 boxes linked by channels of 1 µm × 1 µm × 0.019 µm and 2 µm × 2 µm × 0.010 µm respectively. These data did not scale anywhere in the critical region 13 . The lack of scaling is unexpected, because for both twoand one-dimensional crossover, at least for T > T λ , other data do scale 14 . More significantly, an analysis of the zero-dimensional data suggested that the smaller boxes had a higher heat capacity than expected 13 . This might result from ...

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Section: Figure 1 | the Confinement Cellsupporting

confidence: 69%

Section: Figure 1 | the Confinement Cellmentioning

confidence: 72%

Section: Figure 1 | the Confinement Cellmentioning

confidence: 99%

Section: Figure 1 | the Confinement Cellmentioning

confidence: 99%

Section: Figure 1 | the Confinement Cellmentioning

confidence: 99%

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Coupling and proximity effects in the superfluid transition in 4He dots

et al. 2010

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Wettability and Applications of Nanochannels

2018

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Wettability in nanochannels is of great importance for understanding many challenging problems in interface chemistry and fluid mechanics, and presents versatile applications including mass transport, catalysis, chemical reaction, nanofabrication, batteries, and separation. Recently, both molecular dynamic simulations and experimental measurements have been employed to study wettability in nanochannels. Here, wettability in three types of nanochannels comprising 1D nanochannels, 2D nanochannels, and 3D nanochannels is summarized both theoretically and experimentally. The proposed concept of “quantum‐confined superfluid” for ultrafast mass transport in nanochannels is first introduced, and the mostly studied 1D nanochannels are reviewed from molecular simulation to water wettability, followed by reversible switching of water wettability via external stimuli (temperature and voltage). Liquid transport and two confinement strategies in nanochannels of melt wetting and liquid wetting are also included. Then, molecular simulation, water wettability, liquid transport, and confinement in nanochannels are introduced for 2D nanochannels and 3D nanochannels, respectively. Based on the wettability in nanochannels, broad applications of various nanochannels are presented. Finally, the perspective for future challenges in the wettability and applications of nanochannels is discussed.

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Giant Coupling Effects in Confined 4He Near T λ

Perron

Gasparini

2010

J Low Temp Phys

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Finite-size scaling ofHe4at the superfluid transition

Cited by 98 publications

References 188 publications

Coupling and proximity effects in the superfluid transition in 4He dots

Coupling and proximity effects in the superfluid transition in 4He dots

Wettability and Applications of Nanochannels

Giant Coupling Effects in Confined 4He Near T λ

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