共查询到20条相似文献,搜索用时 62 毫秒
1.
Mario Rabinowitz 《International Journal of Theoretical Physics》1993,32(4):565-574
A basic and inherently simple connection is shown to exist between superconductivity and superfluidity. It is shown that the author's previously derived general equation, which agrees well with the superconducting transition temperatures for the heavy-electron superconductors, metallic superconductors, oxide superconductors, metallic hydrogen, and neutron stars, also works well for the superfluid transition temperature of 2.6 mK for liquid3He. Reasonable estimates are made from 10–3 to 109 K — a range of 12 orders of magnitude. The same paradigm applies to the superfluid transition temperature of liquid4He, but results in a slightly different equation. The superfluid transition temperature for dilute solutions of3He in superfluid4He is estimated to be l–10K. This paradigm works well in detail for metallic, cuprate, and organic superconductors. 相似文献
2.
Jürgen Gspann 《Zeitschrift für Physik B Condensed Matter》1995,98(3):405-411
Free helium clusters with of the order of 103 to 107 atoms have been predicted to reach final temperatures of about 0.4 K in the case of4He, and of 0.15 K in the case of3He. In the first case, the clusters have to be expected to be superfluid, in the latter case to be normalfluid. Impact experiments with cesium atoms, which are calculated to be strongly repelled from inside liquid4He, and slightly from liquid3He, indicate cesium embedding into or onto4He clusters. Xenon atoms, calculated to be strongly bound to both quantum liquids, show incomplete momentum transfer to4He as well as to3He clusters at higher impact speeds. 相似文献
3.
We calculate gap functions, superfluid densities, critical currents, and susceptibilities for the B phase of 3He in the presence of currents and a magnetic field. The distortion of the gap function is properly taken into account. 相似文献
4.
E. M. Alakshin Yu. M. Bunkov R. R. Gazizulin A. V. Klochkov V. V. Kuzmin R. M. Rakhmatullin A. M. Sabitova T. R. Safin M. S. Tagirov 《Applied magnetic resonance》2013,44(5):595-603
The Bose–Einstein condensation of magnons was observed in 1984 in superfluid 3He–B. The same phenomena should exist in solid magnetic systems. We describe here a partly digital experimental setup for studying solid antiferromagnets CsMnF3 and MnCO3 by pulse and continuous wave nuclear magnetic resonance. With this equipment, the Bose–Einstein condensation of magnons was observed for the first time in these single crystals. 相似文献
5.
Frank Berkshire 《Contemporary Physics》2013,54(4):389-390
A comparison of the basic properties of the superfluid phases of liquid 3He with those of electrons in Type I superconductors and of bosons in liquid 4He reveals their similarity and differences. This is followed by some examples of the liquid crystal and magnetic properties of superfluid 3He and an account of the relationships between the tensor order parameter and the collective modes of the superfluid phases. The article ends with some comments on our present understanding of quantum liquids. 相似文献
6.
Formation of self-organized macroscopic and periodic structures in a physical system of interacting fermions are derived from first principles. The system of structureless and chargeless fermions with magnetic moments can have four different phases. Two of these phases exhibit the totally unique phenomena typical for superconductivity and superfluidity as well as various kinds of structural singularities such as disgyrations in the superfluid 3He. 相似文献
7.
D. V. Efremov M. S. Mar’enko M. A. Baranov M. Yu. Kagan 《Journal of Experimental and Theoretical Physics》2000,90(5):861-871
Higher-order perturbation-theory corrections to the superfluid transition temperature in a weakly nonideal Fermi gas with repulsion are determined. This involves calculating the contribution of third-and fourth-order diagrams in terms of the gas parameter ap F to the effective interaction which determines the super-fluid transition temperature and also allowing for effects associated with retardation and renormalization of the polar part of the Green’s function. The expressions obtained provide evidence in support of attraction in the effective interaction in the second, third, and fourth orders of perturbation theory. It is shown that the critical temperature is mainly determined by second-and third-order terms of perturbation theory. Calculations are made of the superfluid transition temperature for a gas comprising neutral Fermi particles in a magnetic field. The limits of validity of the theory are analyzed and the possibility of applying the results to dilute solutions of 3He in 4He and neutral-particle Fermi gases in magnetic traps is discussed. 相似文献
8.
V.I. Kruglov 《Physics letters. A》2011,375(45):4058-4064
Two mechanisms of transition of the superfluid liquid 4He to quantum turbulence regimes are proposed for the case when the influence of the normal fluid on superfluid flow is suppressed by introducing superleaks at the ends of the capillary. Using dimensional analysis it is found that in the roton mechanism the critical velocity depends on channel size as vc∝d−1/4, matching the experiments. For the second, super-flow mechanism, the analysis of independent parameters relevant for this phenomena leads to critical velocity depending on d as vc∝d−1. It is shown that turbulence for super-flow mechanism arises when a “quantum Reynolds number” exceeds some critical value which is about 103 for 1D geometry. The dimensional analysis of the equation for critical velocity of superfluid flow without superleaks at the ends of the capillary is also presented. 相似文献
9.
W. P. Halperin D. T. Sprague T. M. Haard J. B. Kycia Y. Lee M. R. Rand 《Czechoslovak Journal of Physics》1996,46(6):2989-2994
The transition to superfluidity of3He in high porosity (98.2%) acrogel has been observed by nuclear magnetic resonance techniques. The onset of the transition at all pressures above 13 bar is marked by a sharp increase in NMR frequency similar to that observed in bulk3He-A. This suggests that the aerogel/superfluid phase is highly homogeneous although both the transition temperature, Tc, and the amplitude of the order parameter are substantially suppressed. The acrogel strands are ≈ 50Å in diameter, much smaller than the superfluid coherence length. Consequently, we have attempted to interpret our observations as an impurity scattering problem. Based on our measurements of the magnetic field dependence of Tc it appears that both magnetic and potential scattering play important roles where the magnetic scattering can be associated with solid3He on the aerogel surface. This is determined by isotopic exchange with4He, a process which appears to stabilize a new superfluid state similar to the bulk B-phase. 相似文献
10.
M. D. Girardeau 《Journal of statistical physics》1978,18(2):207-215
A model of free4He atoms interacting with radiation exhibits an equilibrium phase transition in which the atomic ground-state Bose condensation is coupled to condensations of virtual photons and virtually excited atoms of the same macroscopic wavelength. The condensed phase has a twofold polarization degeneracy. It is suggested that this might furnish a mechanism for a discrete symmetry-related phase degeneracy of superfluid liquid4He required to explain the transition according to Tisza's generalized Gibbsian thermodynamics. A more realistic model would require inclusion of repulsive interactions.Supported in part by the National Science Foundation, Grant DMR76-17467. 相似文献
11.
The transition of liquid 3He to the superfluid B phase in aerogel at T=0 is considered. It is shown that in a magnetic field, the quantum phase transition with respect to pressure is split in
two. The amount of splitting δP is estimated. The components of the superfluid density tensor are calculated near the critical pressures.
Zh. éksp. Teor. Fiz. 115, 754–762 (February 1999)
Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor. 相似文献
12.
E. Østgaard 《Zeitschrift für Physik A Hadrons and Nuclei》1971,243(1):79-91
The possibility of superfluidity or superconductivity in neutron or proton subsystems in the nuclear-matter region in neutron stars is investigated. The energy gap and corresponding critical temperature and critical magnetic field is calculated or estimated as function of density or Fermi momentum. In the calculations are used reaction matrix elements calculated earlier by means of Brueckner theory by the author. The final results indicate that neutron superfluidity, corresponding specifically toS-state pairing, may exist in a low-density shell in the nuclear-matter region of a neutron star. There is probably anisotropic neutron superfluidity, corresponding to the3 P 2 or the singletD state, for higher densities. Superfluidity or superconductivity, corresponding toS-state pairing for the proton subsystem, is quite likely in most of the nuclear-matter region. The expected temperatures and magnetic fields in neutron stars seem to be well below the estimated critical temperatures or critical magnetic fields corresponding to the calculated values of the energy gap. However, similar methods have earlier predicted a much too high critical temperature for liquid3He. 相似文献
13.
The p-wave phases of superfluid 3He are classified without the unitary constraint or the constraints on the net nuclear magnetization and the magnetic susceptibility. 相似文献
14.
We discuss the effective metric experienced by the Nambu–Goldstone mode propagating in the broken symmetry spin-superfluid state of coherent precession of magnetization. This collective mode represents the phonon in the RF driven or pulsed out-of-equilibrium Bose–Einstein condensate (BEC) of optical magnons. We derive the effective BEC free energy and consider the phonon spectrum when the spin superfluid BEC is formed in the anisotropic polar phase of superfluid 3He, experimentally observed in uniaxial aerogel 3He-samples. The coherent precession of magnetization experiences an instability at a critical value of the tilting angle of external magnetic field with respect to the anisotropy axis. From the action of quadratic deviations around equilibrium, this instability is interpreted as a Minkowski-to-Euclidean signature change of the effective phonon metric. We also note the similarity between the magnon BEC in the unstable region and an effective vacuum scalar “ghost” condensate. 相似文献
15.
V. V. Dmitriev D. A. Krasnikhin N. Mulders V. V. Zavjalov D. E. Zmeev 《JETP Letters》2008,86(9):594-599
It is found that the properties of nuclear magnetic resonance of both superfluid phases of 3He in an anisotropic aerogel can be described in terms of the bulk superfluid order parameters with the orbital order parameter
vector fixed by anisotropy of the aerogel sample. It is also shown that, by proper squeezing, it is possible to attain a sample
with isotropic NMR properties. 相似文献
16.
V. B. Efimov A. V. Lokhov L. P. Mezhov-Deglin C. Dewhurst V. V. Nesvizhevsky G. V. Kolmakov 《JETP Letters》2014,99(1):32-36
The first results of the study of the structure of an impurity oxygen gel in superfluid He-II and in normal liquid helium have been obtained by the small-angle neutron scattering (SANS) method with cold neutrons. The angular dependence of the neutron scattering intensity I(q) indicates that the characteristic sizes of nanocluster aggregates forming a dispersive system (backbone) of an oxygen gel sample are distributed from 1 to ≈100 nm. According to the estimates made, if the working cell with superfluid helium cooled below 1.8 K is placed in a magnetic field of H ≥ 200 G, the magnetic structure of the nanocluster sample of oxygen gel, which is formed at the condensation of the flow of gaseous 4He with the impurity of O2 vapor on the surface of He-II, will be close to ferromagnetic. 相似文献
17.
18.
The superfluid transitions temperature is calculated from the microscopic theory of a Fermi liquid in terms of the Landau parameters and one unknown scale factor. Determining the latter from the observed transition in 3He leads to an estimate that the superfluid transition in 3He4He mixtures may be presently observable. 相似文献
19.
V. V. Dmitriev D. A. Krasnikhin N. Mulders V. V. Zavjalov D. E. Zmeev 《JETP Letters》2007,86(9):594-599
It is found that the properties of nuclear magnetic resonance of both superfluid phases of 3He in an anisotropic aerogel can be described in terms of the bulk superfluid order parameters with the orbital order parameter
vector fixed by anisotropy of the aerogel sample. It is also shown that, by proper squeezing, it is possible to attain a sample
with isotropic NMR properties.
The text was submitted by the authors in English. 相似文献
20.
We report the low-frequency sound measurements of the metastable A-like (A*) phase of superfluid 3He confined within a 98% open aerogel matrix in zero magnetic field. The second soundlike (slow) mode provides an accurate determination of the superfluid fraction of (and the transition between) the A* and B phases. The A* and B phases exhibit stable coexistence in the presence of disorder, the ratio of their superfluid fractions (ρ a A* /ρ s B ) is much smaller than that of the bulk A and B phases, and argues that the A* and bulk A phases are distinct. 相似文献