Crystal growth of U2D2 solid3He

Nomura, R.; Hensley, Harvey H.; Matsushita, Tomohiro; Mizusaki, T.

doi:10.1007/bf00753822

Cited by 63 publications

(9 citation statements)

References 14 publications

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“…The observed growth displays a rather strong anisotropy: for instance, the measured velocities of the (110) increase of the growth velocity with the applied driving force dp shows a linear dependence and this is in agreement with measurements made at higher temperatures of (0.6-0.8) mK by Nomura et al [9] and Akimoto et al [10]. The values they obtain for the growth velocities of 3 He crystals are similar to our results for the most stable facets (110) and (100), but this is the first time that the growth velocities can be assigned to particular facets.…”

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confidence: 91%

“…The values they obtain for the growth velocities of 3 He crystals are similar to our results for the most stable facets (110) and (100), but this is the first time that the growth velocities can be assigned to particular facets. The linear dependence of the growth velocity of a facet on the driving overpressure indicates that in our experiments growth cannot be due to thermal activation of twodimensional terraces on a facet, since at 0.55 mK this would give growth rates many orders of magnitude below the measured values, and also a different dependence on dp [9,13]. Thus we conclude that the dominating growth mechanism is spiral growth which is the main growth mechanism in the presence of screw dislocations.…”

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confidence: 57%

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Anisotropy of Growth Kinetics ofH3eCrystals below 1 mK

Tsepelin¹,

Alles²,

Бабкин³

et al. 2002

Phys. Rev. Lett.

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The growth anisotropy of different facets has been measured in 3He crystals at 0.55 mK using a low-temperature Fabry-Pérot interferometer and high-resolution pressure measurements. The observed linear dependence of the growth velocity on the driving force shows that facets grow due to the presence of dislocations. The values of the obtained step energies suggest that 3He has stronger coupling of the liquid-solid interface to the lattice than has been expected. The dependence of the step energy versus the step height is consistent with a quartic power law pointing out that the step-step interactions are of elastic origin.

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confidence: 91%

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confidence: 57%

Anisotropy of Growth Kinetics ofH3eCrystals below 1 mK

Tsepelin¹,

Alles²,

Бабкин³

et al. 2002

Phys. Rev. Lett.

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“…We also measured the growth velocities of almost all observed facets (17). Before our measurements, only an average growth rate of 3 He crystals had been reported (18)(19)(20).…”

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confidence: 99%

Faceting on ³ He crystals

Alles¹,

Бабкин²,

Jochemsen³

et al. 2002

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

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It has been predicted by Landau that, ideally at low temperatures, crystals should show many different types of facets, i.e., flat smooth faces on their surface, but this so-called ''devil's staircase'' phenomenon has been difficult to observe experimentally. In this paper we describe our recent experiments, in which altogether 11 different types of facets have been identified on growing 3 He crystals at the temperature of 0.55 mK by using a unique lowtemperature Fabry-Pé rot interferometer. Previously only 3 types of facets had been seen in this system. We have also measured the growth velocities of different facets, and our interpretation of the obtained results yields the conclusion that 3 He has much stronger coupling of the liquid-solid interface to the crystal lattice than has been expected. After an introduction we present a short theoretical background about the equilibrium crystal shape and the roughening transitions, which is followed by the description of our experimental results and discussion.T he crystals that we find in nature have usually a polyhedral shape. Their surface is covered with smooth faces or facets that correspond to high-symmetry crystallographic orientations (see Fig. 1). These facets have developed on the crystal surfaces during growth when the crystals were formed. It must be pointed out that it is difficult to study the growth dynamics as well as the equilibrium shape of ordinary crystals. The difficulties are caused by big differences in entropy and density between the solid and the adjacent melt or vapor phases and finite thermal conductivities of these bulk phases. As a result, the relaxation processes are highly dissipative and the corresponding time scales extremely long. The equilibrium shapes have therefore been obtained with microscopic metallic crystals which after annealing of several days have showed facets surrounded by rough (rounded) areas on their surface (1).It was predicted by Landau in the middle of the last century that, in the limit of low temperatures, any ideal crystal should be completely faceted, with an infinite number of facets on its surface (2). This is the so-called ''devil's staircase '' phenomenon (3, 4). The most complicated crystals, however, have shown at most six types of facets. Only very recently Pieranski and his coworkers (5) were able to grow lyotropic monocrystals that revealed more than 60 types of facets on their surface, confirming experimentally the devil's staircase phenomenon. They interpreted their results as the coincidence of a quite large surface tension and interplanar distance with an exceptionally low elastic modulus. But with liquid lyotropic crystals, faceting can be studied in a very limited temperature range and it is hard to measure their equilibrium shape.The experimental situation is more promising in helium crystals, which exist at low temperatures and high pressures. The dynamics of helium crystals, which are surrounded by a superfluid with high thermal conductivity, can be extremely fast. For instance, 4 He crystals...

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“…In case of 3 He which has a large negative slope of the melting curve below 300 mK, heat pulses have been used to nucleate a crystal of the nuclear spin ordered phase from metastable superfluid B-phase at ultra low temperatures [9,10,11]. Warming by the heat pulse with constant pressure resulted in the overpressure of the system and the crystal was nucleated.…”

Section: Introduction Crystal-superfluid Transition Inmentioning

confidence: 99%

Nucleation of crystals and superfluid droplets in ⁴ He by heat pulse

Ogasawara

Abe

Saitoh

et al. 2004

phys. stat. sol. (c)

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Both nucleation of a4 He crystal in superfluid and that of a 4 He superfluid droplet in crystal were found to be induced by a heat pulse at the melting pressure. The time evolutions of nucleation on a heater were directly recorded by a high-speed camera. Duration of the heat pulse was usually 2 msec in this report. The nucleated crystal grew with facets for 4 msec and melted with an irregular shape in 40 msec at 500 mK. The nucleated superfluid droplet in crystal also grew with facets, which was a so-called negative crystal, and disappeared in 10 msec. Introduction Crystal-superfluid transition in4 He is an example of the first order phase transition at very low temperatures where the thermal fluctuations are much smaller than the energy barrier for nucleation of the stable phase. In such a temperature region, nucleation through macroscopic quantum tunneling was theoretically predicted by Kagan and Lifshitz [1]. Nucleation of the 4 He crystal has been studied extensively using several kinds of driving forces. Application of hydrostatic pressure and electric field can induce the nucleation of a 4 He crystal in metastable superfluid with a typical overpressure of 5 mbar above the melting pressure [2][3][4][5]. An overpressure of about 5 bar was achieved by focused sound at the focusing spot on a clean glass plate and nucleation was realized [6]. We recently demonstrated that an acoustic wave can induce both nucleation of a 4 He crystal in superfluid and that of a superfluid droplet in crystal at melting pressure [7,8]. We attributed this reversible nucleation to the acoustic radiation pressure.However, it is not known whether or not a heat pulse can nucleate a crystal in 4 He. In case of 3 He which has a large negative slope of the melting curve below 300 mK, heat pulses have been used to nucleate a crystal of the nuclear spin ordered phase from metastable superfluid B-phase at ultra low temperatures [9,10,11]. Warming by the heat pulse with constant pressure resulted in the overpressure of the system and the crystal was nucleated. The melting curve of 4 He has a much smaller negative slope; minimum of the melting curve exists at 775 mK and the melting pressure increases about 8 mbar with cooling [12]. Slight heating of the system in 4 He causes only a small overpressure and it has never been regarded as an effective driving force. However, we did observe not only nucleation of 4 He crystals in a superfluid but also nucleation of superfluid droplets in a crystal by heat pulse as in the case of acoustic waves. Heat pulse nucleation is nucleation under a steady heat current and it is very interesting to study the nucleation in such a non-equilibrium condition. We report high-speed images of the nucleation of 4 He crystals and superfluid droplets in this paper.

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Crystal growth of U2D2 solid3He

Cited by 63 publications

References 14 publications

Anisotropy of Growth Kinetics ofH3eCrystals below 1 mK

Anisotropy of Growth Kinetics ofH3eCrystals below 1 mK

Faceting on ³ He crystals

Nucleation of crystals and superfluid droplets in ⁴ He by heat pulse

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Crystal growth of U2D2 solid3He

Cited by 63 publications

References 14 publications

Anisotropy of Growth Kinetics ofH3eCrystals below 1 mK

Anisotropy of Growth Kinetics ofH3eCrystals below 1 mK

Faceting on 3 He crystals

Nucleation of crystals and superfluid droplets in 4 He by heat pulse

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Faceting on ³ He crystals

Nucleation of crystals and superfluid droplets in ⁴ He by heat pulse