Publisher’s Note: Observation of Self-Binding in Monolayer<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi>He</mml:mi><mml:mprescripts /><mml:none /><mml:mn>3</mml:mn></mml:mmultiscripts></mml:math>[Phys. Rev. Lett.<b>109</b>, 235306 (2012)]

Sato, D.; Naruse, Keitaro; Matsui, Tamao; Fukuyama, Hiroshi

doi:10.1103/physrevlett.109.269901

Cited by 13 publications

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“…We can assign tentatively that transition to the gas-liquid equilibrium suggested in Ref. [1] for 3 He on clean graphite. We have to stress also that we did not use different trial wavefunctions for gas and liquid phases, the instability appearing naturally when we increase the helium density.…”

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confidence: 62%

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Liquid and Solid Phases ofHe3on Graphite

Gordillo

Boronat

2016

Phys. Rev. Lett.

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Recent heat-capacity experiments show quite unambiguously the existence of a liquid 3 He phase adsorbed on graphite. This liquid is stable at an extremely low density, possibly one of the lowest found in Nature. Previous theoretical calculations of the same system, and in strictly two dimensions, agree with the result that this liquid phase is not stable and the system is in the gas phase. We calculated the phase diagram of normal 3 He adsorbed on graphite at T = 0 using quantum Monte Carlo methods. Considering a fully corrugated substrate we observe that at densities lower that 0.006Å −2 the system is a very dilute gas, that at that density is in equilibrium with a liquid of density 0.014Å −2 . Our prediction matches very well the recent experimental findings on the same system. On the contrary, when a flat substrate is considered, no gas-liquid coexistence is found, in agreement with previous calculations. We also report results on the different solid structures, and the corresponding phase transitions that appear at higher densities.PACS numbers: 05.30. Fk, 67.30ej Recent heat capacity measurements of 3 He adsorbed on graphite by Sato et al. [1,2] have shown that its monolayer is a stable liquid in the density range 0.006-0.009Å −2 . One of the most interesting aspects of this phase is its extremely low density, with interparticle distances as large as 10Å, which could constitute one of the lowest-density stable liquids in nature. This new finding has re-opened an old issue that has been under discussion for more than thirty years, i.e., the nature (gas or liquid) of two-dimensional (2D) 3 He [3,4]. Previous experiments showed contradictory results due in part to the different setups and employed substrates [5][6][7][8]. Now, the new data from Ref.[1] on a clean graphite substrate seem to incline the debate towards the confirmation of this liquid phase existence.On the theoretical side, there is a broad consensus on the gas character of strictly 2D3 He [9-13]. However, the practical need of a substrate to actually realize the 3 He monolayer could modify this result. Previous attempts to calculate the properties of the adsorbed monolayer in a strongly attractive substrate such as graphite arrived to the same result. In Ref. [14], it is shown that the possibility of 3 He atoms moving perpendicularly to the surface leads to a stable liquid phase when the substrate is weakly attractive, as on some alkali metal surfaces. This is probably expected because the system goes from a 2D film to a three-dimensional (3D) configuration where liquid 3 He is the ground-state phase.In this work, we concerned ourselves with the adsorption of 3 He on a clean surface of graphite, trying to reproduce the recent experimental findings of Sato et al.[1] Our goal was to bridge the discrepancy between the strictly 2D calculations and the experimental data by improving the theoretical description of the system.Since considering a quasi-two dimensional flat adsorbent is clearly not enough for graphite [14], we included the effects of ...

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confidence: 62%

“…In this work, we concerned ourselves with the adsorption of 3 He on a clean surface of graphite, trying to reproduce the recent experimental findings of Sato et al [1] Our goal was to bridge the discrepancy between the strictly 2D calculations and the experimental data by improving the theoretical description of the system.…”

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confidence: 99%

Liquid and Solid Phases ofHe3on Graphite

Gordillo

Boronat

2016

Phys. Rev. Lett.

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“…These studies show that the fluid component is close to constant in density but it is distinct from the dense self-bound liquid state observed by Sato et al [13] for very low coverages. At low temperatures, T < 0.7 K, the solid component begins to dominate the relaxation, and we observe the onset of a stronger temperature dependence (shown by the dotted line in Fig.…”

Section: Resultsmentioning

confidence: 64%

“…Experimental studies by Bhattacharyya and Gasparini [5,6] offered evidence for such a phase but the majority of experiments [7][8][9] and the most recent theoretical treatments [10][11][12] do not support the existence of a low temperature gas phase. Recent thermodynamic measurements by Sato et al [13,14], however, for 3 He adsorbed on bare graphite (and on 4 He plated graphite), have provided new evidence in support of a self-bound state for very low coverages at very low temperatures. We have carried out NMR studies at much higher coverages of 0.41 and 0.62 of a full monolayer and at higher temperatures to determine the microscopic dynamics of the 3 He atoms and the mechanisms of diffusion at coverages near the fluid-solid phase transition region [12,15].…”

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NMR Studies of ³He Films on Boron Nitride

Tang

Sullivan

2014

J. Phys.: Conf. Ser.

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Abstract.We report the results of NMR studies of the dynamics of 3 He adsorbed on hexagonal boron nitride. These studies can identify the phase transitions of the 2D films as a function of temperature. A thermally activated temperature dependence is observed for 2.6 < T < 8 K compared to a linear temperature dependence for 0.7 < T < 2.6 K. This linear dependence is consistent with that expected for thermal diffusion in a fluid for coverages of 0.4 -0.6 of a monolayer. IntroductionHelium-three monolayer and submonolayer films are of great interest because the different phases and microscopic dynamics that occur are dominated by quantum effects that lead to new phenomena in reduced dimensions at low temperatures [1,2]. In addition the films are ideal for testing our understanding of the quantum dynamics and spin ordering in two dimensions from first principles [3]. At low temperatures it had been postulated that the large quantum mechanical zero-point kinetic energy of the 3 He atoms could be sufficient to prevent the system from condensing as a 2D liquid in some scenarios [4], leading to a unique quantum gas at extremely low temperatures. Experimental studies by Bhattacharyya and Gasparini [5,6] offered evidence for such a phase but the majority of experiments [7][8][9] and the most recent theoretical treatments [10][11][12] do not support the existence of a low temperature gas phase. Recent thermodynamic measurements by Sato et al. [13,14], however, for 3 He adsorbed on bare graphite (and on 4 He plated graphite), have provided new evidence in support of a self-bound state for very low coverages at very low temperatures. We have carried out NMR studies at much higher coverages of 0.41 and 0.62 of a full monolayer and at higher temperatures to determine the microscopic dynamics of the 3 He atoms and the mechanisms of diffusion at coverages near the fluid-solid phase transition region [12,15]. At these coverages NMR studies by Crane and colleagues [16] for 3 He on BN showed evidence of a mixed coverage of fluid and solid components with the solid melting near 1.6K to form a dense fluid state with appreciable orientational order imposed by the substrate. We have carried out studies using a much higher NMR frequency which should help distinguish between the fluid and solid components.In addition to measuring the diffusion in the fluid phase, NMR studies can be used to determine the spin exchange rates in the solid phases. Below monolayer coverage, the 3 He monolayer forms a commensurate √ 3 × √ 3 solid structure that provides a unique testing ground for the multi-particle exchange model [17,18] invoked to explain the magnetic properties of bulk 3 He and 3 He films [15,19,20]. For example, coverages less than the ideal commensurate structure lead to a reduced probability of 3-particle exchange compared to the 2-particle exchange and

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“…Recent heat-capacity studies of 3 He on graphite, [1][2][3] both clean and preplated, have reopened the interest on the phase diagram of this quasi-two dimensional (quasi-2D) system. In essence, those results confirm a previous hint about the existence of a stable 3 He liquid at very low densities, 4 and are the continuation of a wealth of experimental work on this quantum fluid.…”

Section: Introductionmentioning

confidence: 99%

He3on preplated graphite

Gordillo

Boronat

2016

Phys. Rev. B

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By using the diffusion Monte Carlo method, we obtained the full phase diagram of 3 He on top of graphite preplated with a solid layer of 4 He. All the 4 He atoms of the substrate were explicitly considered and allowed to move during the simulation. We found that the ground state is a liquid of density 0.007 ± 0.001Å −2 , in good agreement with available experimental data. This is significantly different from the case of 3 He on clean graphite, in which both theory and experiment agree on the existence of a gas-liquid transition at low densities. Upon an increase in 3 He density, we predict a first-order phase transition between a dense liquid and a registered 7/12 phase, the 4/7 phase being found metastable in our calculations. At larger second-layer densities, a final transition is produced to an incommensurate triangular phase.

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Publisher’s Note: Observation of Self-Binding in MonolayerHe3[Phys. Rev. Lett.109, 235306 (2012)]

Cited by 13 publications

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Liquid and Solid Phases ofHe3on Graphite

Liquid and Solid Phases ofHe3on Graphite

NMR Studies of ³He Films on Boron Nitride

He3on preplated graphite

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Publisher’s Note: Observation of Self-Binding in MonolayerHe3[Phys. Rev. Lett.109, 235306 (2012)]

Cited by 13 publications

References 0 publications

Liquid and Solid Phases ofHe3on Graphite

Liquid and Solid Phases ofHe3on Graphite

NMR Studies of 3He Films on Boron Nitride

He3on preplated graphite

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Product

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About

NMR Studies of ³He Films on Boron Nitride