Percolative Superconductivity

[fckm]

What does the "percolative" refer to? Anyone know?

[Hain]

Well some other definitions of percolate that I never really thought of as definitions:

Originally Posted by Google.com

- gain or regain energy
- permeate or penetrate gradually
- spread gradually
- cause (a solvent) to pass through a permeable substance in order to extract a soluble constituent

Some of these sound interesting enough to apply to superconductivity. Where did you see this "Percolative Superconductivity?"

[fckm]

In reference to high temperature superconductors, a la YBCO and BLCO. At this point, I think it's refering to a different theory of superconductivity, since high transition temperature superconductors are unaccounted for by BCS theory.

[avernus]

I have never heard of a theory called percolative superconductivity in high temperature superconductors - the most popular ones at the moment are the anisotropic Ginzburg-Landau and the Lawrence-Doniarch model, which is chosen depends largely upon the anisotropy.

A brief search indicates that it might be to do with defects or inhomogenities - these are preferential sites for vortices and are very important in maintaining low resistance when current is flowing.

It could be to do with the spread or percolation of phase transitions in a sample under an appied field. For example, edge defects cause barriers to penetration that are greater than the thermodynamic transition Hc1, this results in almost lightening like domains of penetration (on a large scale). These spread to the center of the sample as the field is increased. Could this be the percolation that you refer to?

[fckm]

It doesn't really matter anymore since my lab report is done, but from Bednorz and Muller, 1986:

In BaPbBiO, the onset of superconductivity has been taken at the resistivity peak. This assumption appears to be valid in percolative systems, i.e., in the thin films consisting of polycrystals with grain boundaries, or when different crystalline phases with interpenetrating grains are present, as found in the Li-Ti-O or in our Ba-La-Cu_O system.