Third sound and the superfluid parameters of thin helium films

Rudnick, I.; Fraser, Jim

doi:10.1007/bf00628145

Cited by 53 publications

(10 citation statements)

References 9 publications

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“…More specifically, these and other experiments [3] showed that on amorphous substrates superfluidity is possible once the 4 He surface coverage n 4 exceeds a threshold value n 0 and that the superfluid onset temperature T s increases linearly with coverage with the KT slope, i.e. T s / n 4 ÿ n 0 .…”

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confidence: 64%

“…It is tempting to consider the 4 He film at T 0 as being formed of two independent subsystems: the inert layer of coverage n 0 and the superfluid layer of coverage n 4 ÿ n 0 . This idealization is often called the inert layer model and it has been used to explain early measurements [2,3]. Recent superflow [4,5] and thermodynamic [5,6] experiments found, however, that this simple model is inadequate.…”

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confidence: 99%

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Substrate-Tuned Boson Localization in SuperfluidHe4Films

2003

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We have studied the influence of the substrate on superfluidity in thin 4He films. The inert coverage, the amount of nonsuperfluid 4He localized by the substrate, is found to scale with the well depth of the 4He-substrate interaction potential for six different substrates. Although the inert coverages for these substrates differ by more than a factor of 4, the phase boundary in the temperature-coverage plane is found to have a universal shape.

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confidence: 64%

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confidence: 99%

Substrate-Tuned Boson Localization in SuperfluidHe4Films

2003

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“…Superfluidity in films on surfaces and on the walls of porous media has similarly been extensively investigated [42][43][44][45][46][47][48][49] . At low temperature, a threshold coverage is needed before superfluidity is observed.…”

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confidence: 99%

Localized Bose-Einstein condensation in disordered liquidHe4films

2015

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We present neutron scattering measurements of the phonon-roton and layer modes of liquid helium films adsorbed in 25Å pore diameter gelsil as a function of temperature. The goal is to determine whether the well-defined phonon-roton and layer modes observed at low temperature at partial fillings of the porous media persist as well-defined modes at higher temperatures above the superfluid phase, as is the case of fully filled pores (3D liquid). We find that well defined P-R modes exist in films at temperatures well above the superfluid phase. This is the case at all fillings investigated. Liquid 4 He in porous media is an example of a Bose liquid in disorder. The existence of P-R modes above Tc suggests the existence of patches or islands of Bose condensed liquid having long range order (localized Bose-Einstein condensation (LBEC)) above Tc. The interpretation is that the welldefined P-R modes propagate in the patches of BEC. Gelsil partially filled with liquid helium shows the same LBEC behavior as found previously in fully filled gelsil (as in a 3D liquid).

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“…On strong binding substrates 4 He shows superfluid behavior for film coverages that exceed two monolayers of inert 4 He adjacent to the substrate [1]. On a H 2 substrate, which is a much weaker-binding substrate, 4 He exhibits superfluidity at submonolayer coverages [2 -6].…”

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confidence: 99%