Fast Diffusion Process in Quenched hcp Dilute Solid 3He–4He Mixture

Vekhov, Ye.; Birchenko, A. P.; Mikhin, N. P.; Rudavskiı̆, É. Ya.

doi:10.1007/s10909-009-0022-9

Cited by 12 publications

(24 citation statements)

References 21 publications

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“…The structures of the interphase and twin boundaries are related closely [5]. Therefore, the above predicted arising of quantum diffusion and the experimentally observed one [13] are closely related. The relation k 21 /k is depends on a crystal lattice geometry and nature of interaction only; they can be varied slightly under high pressure.…”

Section: Atom As Anisotropic Harmonic Oscillator In the Boundary Onesupporting

confidence: 55%

“…The high concentration of the defects can lead to formation of the glass phase. Great role of the interface in increasing of quantum diffusion was found by the NMR experiments (see [13] and references therein). Stacking fault energy in single hcp crystals 4 He was measured in [14].…”

Section: Introductionmentioning

confidence: 85%

“…The exchange integral I defines the diffusion coefficient: D ∼ I [24]. The quantum diffusion increasing was observed for the interphase boundaries in solid helium by NMR experiment [13]. The structures of the interphase and twin boundaries are related closely [5].…”

Section: Atom As Anisotropic Harmonic Oscillator In the Boundary Onementioning

confidence: 96%

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Quantum Behavior of the Twin Boundary and the Stacking Fault in hcp Helium Crystals

Lykah

Syrkin

2015

J Low Temp Phys

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The 180 • twin boundary (stacking fault) is investigated in the hexagonal close-packed (hcp) lattice. It is shown that the interatomic interaction between neighbors within the boundary lowers symmetry as compared with that in hcp phase. An initial spherical form (hcp phase) is elongated along the shift direction of the atomic planes inside the boundary. We find the wave functions of the helium atom for (i) the spherical oscillator (within the hcp phase) and (ii) an anisotropic one (inside the boundary). To estimate the parameters of the thermodynamic potential we apply the model of spheres and ellipsoids for the isosurfaces of the probability. Method of the successive approximations is applied for the self-consistent description of the distorted wave functions of atoms. It is shown that the quantum behavior of the boundary atoms causes the following effects: (i) increasing of degree of overlap of the atomic wave functions within the twin boundaries, (ii) increasing of the quantum diffusion inside the twin boundaries, (iii) decreasing of energy and broadening of the boundary in comparison with the classical case.

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Section: Atom As Anisotropic Harmonic Oscillator In the Boundary Onesupporting

confidence: 55%

Section: Introductionmentioning

confidence: 85%

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Quantum Behavior of the Twin Boundary and the Stacking Fault in hcp Helium Crystals

Lykah

Syrkin

2015

J Low Temp Phys

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“…The shape and spectrum of the local vibrations of the order parameter are found for both models of the PB. Basically, the role of interfaces for the existence of high dissipation and high diffusion is shown in nuclear magnetic resonance (NMR) experiments in solid mixtures of 3 He- 4 He [8,15,16]. We show that the local oscillation of the coherent phase boundaries may be responsible for these phenomena.…”

mentioning

confidence: 84%

“…This decrease in size of inclusions is possible with the increase in rate of cooling of the sample. In fact, it is quenching [16].…”

Section: Modelsmentioning

confidence: 99%

Local oscillations in different models of the coherent bcc–hcp boundary in ⁴He and metals

Lykah

Syrkin

2011

Physica Status Solidi (b)

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Small local vibrations of the order parameter (the relative displacement of atomic planes) on the coherent phase boundary (PB) in the bcc-hcp 4 He crystal are investigated theoretically. Dynamical differential equations for small values of the perturbations of the order parameter are obtained. On the coherent PB bcc-hcp for double-and triple-well models the shape and the spectrum are found for small local vibrations of the order parameter. Characteristic frequencies are found and estimated. It is shown that the bcc-hcp boundary in the 4 He crystal is a very soft system. This fact may explain the high degree of damping of 3 He excitations in nuclear magnetic resonance (NMR) experiments.

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NMR Study of Disordered Inclusions in the Quenched Solid Helium

et al. 2012

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Phase structure of rapidly quenched solid helium samples is studied by the NMR technique. The pulse NMR method is used for measurements of spin-lattice $T_1$ and spin-spin $T_2$ relaxation times and spin diffusion coefficient $D$ for all coexisting phases. It was found that quenched samples are two-phase systems consisting of the hcp matrix and some inclusions which are characterized by $D$ and $T_2$ values close to those in liquid phase. Such liquid-like inclusions undergo a spontaneous transition to a new state with anomalously short $T_2$ times. It is found that inclusions observed in both the states disappear on careful annealing near the melting curve. It is assumed that the liquid-like inclusions transform into a new state - a glass or a crystal with a large number of dislocations. These disordered inclusions may be responsible for the anomalous phenomena observed in supersolid region.Comment: 10 pages, 3 figure

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Fast Diffusion Process in Quenched hcp Dilute Solid 3He–4He Mixture

Cited by 12 publications

References 21 publications

Quantum Behavior of the Twin Boundary and the Stacking Fault in hcp Helium Crystals

Quantum Behavior of the Twin Boundary and the Stacking Fault in hcp Helium Crystals

Local oscillations in different models of the coherent bcc–hcp boundary in ⁴He and metals

NMR Study of Disordered Inclusions in the Quenched Solid Helium

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Fast Diffusion Process in Quenched hcp Dilute Solid 3He–4He Mixture

Cited by 12 publications

References 21 publications

Quantum Behavior of the Twin Boundary and the Stacking Fault in hcp Helium Crystals

Quantum Behavior of the Twin Boundary and the Stacking Fault in hcp Helium Crystals

Local oscillations in different models of the coherent bcc–hcp boundary in 4He and metals

NMR Study of Disordered Inclusions in the Quenched Solid Helium

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Local oscillations in different models of the coherent bcc–hcp boundary in ⁴He and metals