Superconductivity penetration depth

Even at the level of mean field approximation (MFA), the GL theory gives significant information such as penetration depth (l) and coherence length ( ) of the superconducting samples. Many unconventional properties of superconductivity connected with the break down of the simple MFA has been studied both analytically (Tesanovich, 1999)... 

When Hj < Hcl, B = 0 in the interior of the superconducting cylinder as shown in Figure 1(b), but magnetic flux enters the walls for a distance A ( 1400 A for fields parallel to the a-b plane in YBajCujOy at low temperatures (23)). Provided the sample is of macroscopic size, the penetration depth is negligible, but it... 

In contrast to the conventional s-wave superconductor picture above, Gasparov et al. (2006) report unusual temperature dependence of the magnetic penetration depth A.(T) and upper critical field Hc2(T) and propose that ZrBi2 has an unconventional two-gap superconductivity. 

There seems to be a growing consensus that the superconductivity is d-wave [97], more specifically, dx2 y2 type. Recent microwave measurements [98] would indicate that the penetration depth is linear in temperature, a sign that the gap has zeros. As pointed out in Ref. 99, this does not exclude 5-wave pairing since harmonics of the basic combinations [Eq. (38)] can also lead to zeros of the gap on the Fermi surface. It is interesting to note that d-wave pairing is quite in line with the extrapolations of the two-dimensional Hubbard and t-J models (Section V.B) and the observed competition with AFM. This would point to a spin-exchange mechanism. The parallel with the quasi-one-dimensional superconductors is striking. 

Figure 7 Temperature dependence of the relative values of the critical current density Jq T), critical field BdT), energy gap Eg, density of superconducting electrons ng, and penetration depth X (T) in the Type II superconducting state below the transition temperature Tc...

Magnetization measurements on the bulk powders of K3C60 allowed the determination of additional parameters of the superconducting state. Upper and lower critical fields were analyzed to determine a penetration depth of A = 2400 A, and a superconducting coherence length of =... 

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