“…They have found some exotic configurations like vortex molecules and multiquanta vortices. Similar results have been independently reported by Doria and Zebende [4]. In our work we find only singly quantized vortex configurations because of the limitations of London theory previously mentioned.…”
In the present paper we consider the vortex lattice properties of a square superconductor such as the vortex patterns, the Gibbs free energy, the magnetization, and the depairing critical current density. We show that this last quantity shows a matching effect, that is, it shows a discontinuous behavior as a function of the applied magnetic field.
“…They have found some exotic configurations like vortex molecules and multiquanta vortices. Similar results have been independently reported by Doria and Zebende [4]. In our work we find only singly quantized vortex configurations because of the limitations of London theory previously mentioned.…”
In the present paper we consider the vortex lattice properties of a square superconductor such as the vortex patterns, the Gibbs free energy, the magnetization, and the depairing critical current density. We show that this last quantity shows a matching effect, that is, it shows a discontinuous behavior as a function of the applied magnetic field.
“…In this magnetic field range, the derivative dM/dH may be compared with a total volume of all superconducting grains, V S = m/ρ, where m is the sample mass and ρ is the bulk density of Y-123. For the sample Y#2, V S is 0.31 mm 3 . Taking an experimental value of dM/dH = 1.45 · 10 −5 emu/Oe, we get (1/V S )(4πdM/dH) = 0.58 < 1, i.e., the volume, from which the magnetic field is expelled, is smaller than V S .…”
Section: Resultsmentioning
confidence: 99%
“…As an estimate we can use the result of Ref. 3 where it was shown that the first vortex is created when the transverse size D ∼ 2D 0 . A similar result was also obtained for very small superconducting spheres.…”
We present a magnetization study of low density YBa2Cu3O7−x ceramics carried out in magnetic fields 0.5 Oe < H < 50 kOe. It was demonstrated that superconducting links between grains may be completely suppressed either by a magnetic field H ∼ 100 Oe (at low temperatures) or by an increase of temperature above 70 K. This property of present samples allowed to evaluate the ratio between an average grain size and the magnetic field penetration depth λ. Furthermore, at temperatures T > 85 K, using low-field magnetization measurements, we could evaluate the temperature dependence of λ, which turned out to be very close to predictions of the conventional Ginzburg-Landau theory. Although present samples consisted of randomly oriented grains, specifics of magnetization measurements allowed for evaluation of λ ab (T ). Good agreement between our estimation of the grain size with the real sample structure provides evidence for the validity of this analysis of magnetization data. Measurements of equilibrium magnetization in high magnetic fields were used for evaluation of Hc2(T ). At temperatures close to Tc, the Hc2(T ) dependence turned out to be linear in agreement with the Ginzburg-Landau theory. The value of temperature, at which Hc2 vanishes, coincides with the superconducting critical temperature evaluated from lowfield measurements.
“…We find numerical solutions of the Ginzburg-Landau theory in the unit cell using a mesh grid to describe it 8,9,10 . The distance between two consecutive mesh points, a, is equal to 0.5ξ, consistent to the fact that a must be smaller than the coherence length ξ, which is the minimum physical scale of the Ginzburg-Landau theory.…”
Section: Theoretical Approachmentioning
confidence: 99%
“…The interaction between a vortex line and a pinning center has been considered by many authors in the context of the Ginzburg-Landau theory 8,9,10,12 . In this paper we only consider the no magnetic shielding limit, such that the field penetrates in the superconductor and there is no Meissner-Ochsenfeld effect.…”
A vortex line is shaped by a zigzag of pinning centers and we study here how far the stretched vortex line is able to follow this path. The pinning center is described by an insulating sphere of coherence length size such that in its surface the de Gennes boundary condition applies. We calculate the free energy density of this system in the framework of the Ginzburg-Landau theory and study the critical displacement beyond which the vortex line is detached from the pinning center.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.