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The superconducting coherence length is a measure of the size of a Cooper pair (distance between the two electrons) and is of the order of cm. The electron near or at the Fermi surface moving through the lattice of a metal produces behind itself an attractive potential of range of the order of 3 × 10 − 6 {\displaystyle 3\times 10^{-6}} cm ...
This is in contrast to single-component superconductors, where there is only one coherence length and the superconductor is necessarily either type 1 (>) or type 2 (<) (often a coherence length is defined with extra / factor, with such a definition the corresponding inequalities are > and <).
Ginzburg–Landau theory introduced the superconducting coherence length ξ in addition to London magnetic field penetration depth λ. According to Ginzburg–Landau theory, in a type-II superconductor / > /. Ginzburg and Landau showed that this leads to negative energy of the interface between superconducting and normal phases.
Multimode helium–neon lasers have a typical coherence length on the order of centimeters, while the coherence length of longitudinally single-mode lasers can exceed 1 km. Semiconductor lasers can reach some 100 m, but small, inexpensive semiconductor lasers have shorter lengths, with one source [4] claiming 20 cm. Singlemode fiber lasers with linewidths of a few kHz can have coherence ...
Phase diagram (B, T) of a type I superconductor : if B < B c, the medium is superconducting. T c is the critical temperature of a superconductor when there is no magnetic field. The interior of a bulk superconductor cannot be penetrated by a weak magnetic field, a phenomenon known as the Meissner effect. When the applied magnetic field becomes ...
Based on Landau's previously established theory of second-order phase transitions, Ginzburg and Landau argued that the free energy density of a superconductor near the superconducting transition can be expressed in terms of a complex order parameter field () = | | (), where the quantity | | is a measure of the local density of superconducting electrons () analogous to a quantum mechanical wave ...
Plot showing superconducting electron density versus depth in normal and superconducting layers with two coherence lengths, and .. Proximity effect or Holm–Meissner effect is a term used in the field of superconductivity to describe phenomena that occur when a superconductor (S) is placed in contact with a "normal" (N) non-superconductor.
Furthermore, the superconducting length scales show similar anisotropy, in both penetration depth (λ ab ≈ 150 nm, λ c ≈ 800 nm) and coherence length, (ξ ab ≈ 2 nm, ξ c ≈ 0.4 nm). Although the coherence length in the a - b plane is 5 times greater than that along the c axis it is quite small compared to classic superconductors such ...