Publisher's Note: Nonlocal effect and dimensions of Cooper pairs measured by low-energy muons and polarized neutrons in type-I superconductors [Phys. Rev. B<b>87</b>, 104508 (2013)]

Кожевников, В. Л.; Suter, A.; Fritzsche, H.; Gladilin, V. N.; Volodin, A.; Moorkens, T.; Trekels, Maarten; Cuppens, J.; Wojek, Bastian M.; Prokscha, T.; Morenzoni, E.; Nieuwenhuys, G.J.; Bael, M. J. Van; Temst, Kristiaan; Haesendonck, C. Van; Indekeu, J. O.

doi:10.1103/physrevb.87.139901

Cited by 4 publications

(11 citation statements)

References 25 publications

(42 reference statements)

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“…Its bulk version makes use of 4 MeV polarized muons, probing B at ∼ 0.1 mm below the sample surface, i.e. in the bulk (see, e.g., [21][22][23] for details).…”

Section: Pacs Numbersmentioning

confidence: 99%

“…Its bulk version makes use of 4 MeV polarized muons, probing B at ∼ 0.1 mm below the sample surface, i.e. in the bulk (see, e.g., [21][22][23] for details).µSR spectra were acquired for the Nb-SC2 sample in perpendicular field at the Dolly instrument of the Swiss Muon Source. Number of events of muon decays collected in each data point is 3 · 10 6 ; statistical error in measured field is 0.1%.…”

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confidence: 99%

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Equilibrium properties of superconducting niobium at high magnetic fields: A possible existence of a filamentary state in type-II superconductors

et al. 2017

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The standard interpretation of the phase diagram of type-II superconductors was developed in 1960s and has since been considered a well-established part of classical superconductivity. However, upon closer examination a number of fundamental issues arise that leads one to question this standard picture. To address these issues we studied equilibrium properties of niobium samples near and above the upper critical field Hc2 in parallel and perpendicular magnetic fields. The samples investigated were very high quality films and single crystal discs with the Ginzburg-Landau parameters 0.8 and 1.3, respectively. A range of complementary measurements have been performed, which include dc magnetometry, electrical transport, µSR spectroscopy and scanning Hall-probe microscopy. Contrarily to the standard scenario, we observed that a superconducting phase is present in the sample bulk above Hc2 and the field Hc3 is the same in both parallel and perpendicular fields. Our findings suggest that above Hc2 the superconducting phase forms filaments parallel to the field regardless on the field orientation. Near Hc2 the filaments preserve the hexagonal structure of the preceding vortex lattice of the mixed state and the filament density continuously falls to zero at Hc3. Our work has important implications for the correct interpretation of properties of type-II superconductors and can also be essential for practical applications of these materials. PACS numbers:Interpretation of equilibrium properties of superconductors has a pivotal significance for the entire realm of quantum physics, extending from neutron stars to the standard model [1,2]. Therefore it is important to verify any concern related to description of these properties.Type-II superconductors subjected to a magnetic field H above the lower critical field H c1 can be found in three equilibrium states [3,4,6,7]: in the mixed state (MS), where average magnetic inductionB < H and currents form vortices organized in a hexagonal lattice; in a "surface superconductivity" state, where B = H everywhere except a sheath with thickness of the order of the Ginzburg-Landau (GL) coherence length near the surface parallel to H; and in the normal state (NS). The typical phase diagram of type-II superconductors of cylindrical geometry (such as, e.g., infinite circular cylinders and slabs with thickness greatly exceeding the penetration depth) in parallel magnetic field, or of massive samples with demagnetizing factor η = 1 [5] is shown in Fig. 1. Transitions between states, occurring at the critical fields H c2 and H c3 , are second order phase transitions. In ellipsoidal samples with η = 0 the sheath formes an equatorial band whose width decreases with increasing η. In samples with η = 1 (infinite slabs in perpendicular field) the band vanishes and surface superconductivity disappears. Since MS in such samples starts from H = (1−η)H c1 = 0, their phase diagram consists of a single curve H c2 . This interpretation of the properties of type-II superconductors is based on two well kno...

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“…Its bulk version makes use of 4 MeV polarized muons, probing B at ∼ 0.1 mm below the sample surface, i.e. in the bulk (see, e.g., [21][22][23] for details).…”

Section: Pacs Numbersmentioning

confidence: 99%

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confidence: 99%

Equilibrium properties of superconducting niobium at high magnetic fields: A possible existence of a filamentary state in type-II superconductors

et al. 2017

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“…At first sight the answers are known [7,9,15,16]. However, ξ 0 in Sn and In, determined from the field profile measurements (310 nm in Sn and 380 nm in In) [19], differ from ξ 0 calculated from δ(0) obtained from the IS (180 [20] and 240 nm [21], respectively). Since in both cases the samples were very pure, this signals the inadequacy of models used either in Ref.…”

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Magnetic flux density and the critical field in the intermediate state of type-I superconductors

et al. 2014

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To address unsolved fundamental problems of the intermediate state (IS), the equilibrium magnetic flux structure and the critical field in a high purity type-I superconductor (indium film) are investigated using magneto-optical imaging with a 3D vector magnet and electrical transport measurements. The least expected observation is that the critical field in the IS can be as small as nearly 40% of the thermodynamic critical field Hc. This indicates that the flux density in the bulk of normal domains can be considerably less than Hc, in apparent contradiction with the long established paradigm, stating that the normal phase is unstable below Hc. Here we present a novel theoretical model consistently describing this and all other properties of the IS. Moreover, our model, based the rigorous thermodynamic treatment of observed laminar flux structure in a tilted field, allows for a quantitative determination of the domain-wall parameter and the coherence length, and provides new insight into the properties of all superconductors. PACS numbers:The interest in pattern formation in a big variety of physicochemical systems with spatially modulated phases [1] has sparked renewed attention to the intermediate state (IS) in type-I superconductors [2-6], a classical example of such systems with very rich physics [7].

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“…(4) for which Pippard suggested a non-local extension of the London theory [29]. It is also consisted with experiment [30][31][32].…”

Section: London Theorymentioning

confidence: 99%

“…Apparently, that p 10 and p 20 in Eq. (18) can not be directed toward each other or vice versa, because in such case Cooper pairs would not be stable 32. Naturally, the Lorentz force acts on "normal" (non-coupled) conduction electrons as well resulting in a weak Landau diamagnetism[47,48].…”

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Meissner Effect: History of Development and Novel Aspects

Кожевников

2021

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The discovery of the Meissner (Meissner–Ochsenfeld) effect in 1933 was an incontestable turning point in the history of superconductivity. First, it demonstrated that superconductivity is an unknown before equilibrium state of matter, thus allowing to use the power of thermodynamics for its study. This provided a justification for the two-fluid model of Gorter and Casimir, a seminal thermodynamic theory founded on a postulate of zero entropy of the superconducting (S) component of conduction electrons. Second, the Meissner effect demonstrated that, apart from zero electric resistivity, the S phase is also characterized by zero magnetic induction. The latter property is used as a basic postulate in the theory of F. and H. London, which underlies the understanding of electromagnetic properties of superconductors. Here the experimental and theoretical aspects of the Meissner effect are reviewed. The reader will see that, in spite of almost nine decades age, the London theory still contains questions, the answers to which can lead to a revision of the standard picture of the Meissner state (MS) and, if so, of other equilibrium superconducting states. An attempt is made to take a fresh look at electrodynamics of the MS and try to work out with the issues associated with this the most important state of all superconductors. It is shown that the concept of Cooper's pairing along with the Bohr–Sommerfeld quantization condition allows one to construct a semi-classical theoretical model consistently addressing properties of the MS and beyond, including non-equilibrium properties of superconductors caused by the total current. As follows from the model, the three “big zeros” of superconductivity (zero resistance, zero induction and zero entropy) have equal weight and grow from a single root: quantization of the angular momentum of paired electrons. The model predicts some yet unknown effects. If confirmed, they can help in studies of microscopic properties of all superconductors. Preliminary experimental results suggesting the need to revise the standard picture of the MS are presented.

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Publisher's Note: Nonlocal effect and dimensions of Cooper pairs measured by low-energy muons and polarized neutrons in type-I superconductors [Phys. Rev. B87, 104508 (2013)]

Abstract: Publisher's Note: Nonlocal effect and dimensions of Cooper pairs measured by low-energy muons and polarized neutrons in type-I superconductors [Phys. Rev. B 87, 104508 (2013)]

Cited by 4 publications

References 25 publications

Equilibrium properties of superconducting niobium at high magnetic fields: A possible existence of a filamentary state in type-II superconductors

Equilibrium properties of superconducting niobium at high magnetic fields: A possible existence of a filamentary state in type-II superconductors

Magnetic flux density and the critical field in the intermediate state of type-I superconductors

Meissner Effect: History of Development and Novel Aspects

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