Bulklike excitations in nanoconfined liquid helium

Bryan, Matthew S.; Prisk, Timothy; Sherline, Todd E.; Diallo, Souleymane; Sokol, P. E.

doi:10.1103/physrevb.95.144509

Cited by 10 publications

(10 citation statements)

References 38 publications

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“…The present results can be most directly compared with those of Prisk et al 18 and Bryan et al 38 for liquid 4 He also confined in 28Å FSM-16. The present FSM-16 sample should be very similar to that used in Refs.…”

Section: P-r Mode Energies and Widthssupporting

confidence: 66%

“…Mode energies, E Q , equal to the bulk liquid energies are reported at 43.0 mmol/g and 46.4 mmol/g (with no filling dependence between 43.0 mmol/g and 46.4 mmol/g). Similarly, at a filling of 47 mmol/g, Bryan et al 38 report an E Q and 2Γ Q as a function of temperature that is the same as those in bulk liquid 4 He .…”

Section: P-r Mode Energies and Widthsmentioning

confidence: 76%

“…We investigate two pressures: (1) a pressure immediately below bulk SVP where there will be liquid in the FSM pores but no bulk liquid in the cell and (2) a pressure somewhat greater than the bulk solidification pressure (p ≥ 25.3 bar at T → 0 K) so that there will be solid 4 He everywhere in the cell except in the FSM-16 nanopores where there will be confined liquid under pressure. Two measurements of P-R modes in FSM at SVP have already been reported, 18,38 an extensive measurement of modes at low temperature 18 and a measurement of the temperature dependence of the P-R mode 38 at the roton wave vector, Q = 1.95Å −1 . We compare directly with these two measurements in the Discussion.…”

Section: Introductionmentioning

confidence: 99%

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Phonons, rotons, and localized Bose-Einstein condensation in liquid He4 confined in nanoporous FSM-16

2019

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We present neutron scattering measurements of the phonon-roton and layer modes of liquid helium confined in 28Å diameter nanopores of FSM-16. The goal is to determine the energy, lifetime and intensity of the modes as a function of temperature. It is particularly to determine the highest temperature, denoted TP R, at which well-defined phonon-roton modes are observed at higher wave vector (Q > 0.8Å −1) in the nanopores. The temperature TP R, which can be identified with loss of Bose-Einstein condensation (BEC), can be compared with the superfluid-normal liquid transition temperature, TO, and other transition temperatures of 4 He in the nanopores. The aim is to identify the nature of BEC in a narrow nanopore. Two pressures are investigated, saturated vapor pressure (SVP) and p = 26 bar. We find that well defined P-R modes are observed up to temperatures much higher than the conventional superfluid to normal liquid transition temperature, TO, observed in torsional oscillator (TO) measurements, i.e. TP R > TO. At SVP, TP R = 1.8 K and TO = 0.9 K. This supports the interpretation that BEC exists in a localized or partially localized form in the temperature range, TO < T < TP R, i.e. there is a localized BEC region lying between the superfluid and fully normal liquid phase, as observed in some other porous media. At close to full filling, the P-R mode energies in FSM-16 are similar to those in bulk liquid 4 He. However, a substantial P-R mode width at T → 0 K and at higher temperatures is observed.

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Section: P-r Mode Energies and Widthssupporting

confidence: 66%

Section: P-r Mode Energies and Widthsmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

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Phonons, rotons, and localized Bose-Einstein condensation in liquid He4 confined in nanoporous FSM-16

2019

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“…41) 21 and FSM-16 (Folded Sheet Material) 22 that consist of regular networks of hexagonal or cylindrical pores. When filled with helium, they are amenable to bulk probes at low temperature and have provided a large body of evidence on the effects of enhanced thermal and quantum fluctuations on the superfluid state [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] . How-ever, the radii of the pores in these materials is ultimately set by the specific reaction route and is not continuously tunable, with the smallest possible diameter being on the order of 2 nm.…”

Section: Introductionmentioning

confidence: 99%

Dimensional Reduction of Helium-4 Inside Argon Plated MCM-41 Nanopores

Nichols,

Prisk,

Warren

et al. 2020

Preprint

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The angstrom-scale coherence length describing the superfluid wavefunction of 4 He at low temperatures has prevented its preparation in a truly one-dimensional geometry. Mesoporous ordered silica-based structures, such as the molecular sieve MCM-41, offer a promising avenue towards physical confinement, but the minimal pore diameters that can be chemically synthesized have proven to be too large to reach the quasi-one-dimensional limit. We present an active nano-engineering approach to this problem by pre-plating MCM-41 with a single, well controlled layer of Ar gas before filling the pores with helium. The structure inside the pore is investigated via experimental adsorption isotherms and neutron scattering measurements that are in agreement with large scale quantum Monte Carlo simulations. The results demonstrate angstrom and kelvin scale tunability of the effective confinement potential experienced by 4 He atoms inside the MCM-41, with the Ar layer reducing the diameter of the confining media into a regime where a number of solid layers surround a one-dimensional quantum liquid.

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“…On the other hand, a host of recent experiments aim to study the quasi-one-dimensional (quasi-1D) properties of helium-4 confined inside regular nanometer sized constrictions. Examples of the restricted geometries include solid helium cells in contact with superfluid helium 4,5 , networks of edge dislocations 6 , and nanopores in mesoporous materials [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] . An alternative approach has been undertaken to study helium-4 mass flow in a single cylindrical nanopore, carved with an electron beam through a thin Si 3 N 4 membrane 16 .…”

Section: Introductionmentioning

confidence: 99%

A shell model for superfluids in rough-walled nanopores

Yang,

Affleck

2020

Preprint

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Recent experiments on the flow of helium-4 fluid through nanopores with tunable pore radius provide a platform for studying the quasi-one-dimensional (quasi-1D) superfluid behaviors. In the extreme 1D limit, the helium atoms are localized by disordered small variations in the substrate potential provided by the pore walls. In the limit of wide pore radius, a solid layer of helium-4 is expected to coat the pore walls smoothing out the substrate potential, and superfluidity is observed in the central region. Building on earlier quantum Monte Carlo results, we propose a scenario for this crossover using a shell model of coupled Luttinger liquids. We find that a small radius pore will always localize the helium atoms, but above a critical radius, a single 1D channel flows through the pore and can be described by Luttinger liquid theory.

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Bulklike excitations in nanoconfined liquid helium

Cited by 10 publications

References 38 publications

Phonons, rotons, and localized Bose-Einstein condensation in liquid He4 confined in nanoporous FSM-16

Phonons, rotons, and localized Bose-Einstein condensation in liquid He4 confined in nanoporous FSM-16

Dimensional Reduction of Helium-4 Inside Argon Plated MCM-41 Nanopores

A shell model for superfluids in rough-walled nanopores

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