Superconductors penetration length

It is also interesting to note that a similar method was used for the first precision determination of the magnetic field penetration length in superconductors [6]. 

Considering a specific example (see Question 20), if a cylindrical, circular section superconductor is magnetized along its length the critical current density J flows throughout the volume in circular paths in planes perpendicular to the axis of the cylinder. The interaction of Jc with the penetrated induction 5p, leads to tensile stresses of magnitude 4/ 0-... 

Table 2 Coherence length f, penetration depth X, and Ginzburg-Landau parameter k =Xj for various superconductors...

When a superconductor S is brought into a contact with a non superconducting (normal) metal N the proximity effect mainly defines the properties of this hybrid structure. The concept of the proximity effect is related to the diffusive penetration of the Cooper pairs from S to N metal over some distance [1]. The condensate wave function monotonically decays in the normal metal due to the finite lifetime of superconducting electrons in it. The characteristic distance of the wave function decay is the coherence length gN = hDNl2tikBT)m, where DN is the diffusion coefficient of N metal, and T is the temperature. The %N values are usually order of dozens of nanometers [2]. When the N layer in a S/N proximity effect structure is replaced by a metallic ferromagnet F, the pair wave function from S still penetrates in F and makes the F layer superconducting. 

Properties and microscopic parameters characterizing the normal and superconducting states of polycrystalline heavy-fermion superconductors T, from speciflc-heat measurements B and, slopes of upper and lower critical-field curves at T p , normal-state (T — 0) resistivity 1, total mean free path I, Ginzburg-Landau coherence length A, London penetration depth k, Ginzburg-Landau parameter 0) B, , B j(T—>0). The other... 

There exists a fundamental length in the detailed theory of superconductivity known as the penetration depth, [10]. It is a measure of the depth of penetration of an applied steady magnetic field into the bulk of a superconductor, and is given approximately by... 

Next came the likewise phenomenological Ginzburg-Landau theory of superconductivity, based on the Landau theory of a second-order phase transition (see also Appendix B) that predicted the coherence length and penetration depth as two characteristic parameters of a superconductor (Ginzburg and Landau, 1950). Based on this theory, Abrikosov derived the notion that the magnetic field penetrates type II superconductors in quantized flux tubes, commonly in the form of a hexagonal network (Abrikosov, 1957). The existence of this vortex lattice was... 

Two important lengths characterize the superconductors the order parameter coherence length = (/ra/ r ) over which yr can vary and the London penetration depth of a magnetic field A=(mc /2 c yr ). ... 

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