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Acta Astronautica, Volume 76, July–August 2012, Pages 37-41
H.P. Roeser, A. Bohr, D.T. Haslam, J.S. Lopez, M. Stepper, A.S. Nikoghosyan
Institute of Space Systems, University of Stuttgart, Pfaffenwaldring 29, 70569 Stuttgart, Germany
Department of Microwave and Telecommunication, Yerevan State University, Alex Manoogian 1, Yerevan, 0025, Armenia
Abstract
Optimum doping of high-temperature superconductors (HTSC) defines a superconducting unit volume for each HTSC. For a single-mode HTSC, e.g., a cuprate with one CuO2 plane, the volume is given by Vsc=cx2, where c is the unit cell height and x the doping distance. The experimental resistivity at Tc is connected to the structure by ρ(exp)≈c×h/(2e2). Combining this result with the classical definition of resistivity leads to an equation similar to Einstein’s diffusion law x2/(2τ)=h/(2Meff)=D, where τ is the relaxation time, Meff=2me and D the diffusion constant. It has also been shown that the mean free path d=x. The Einstein–Smoluchowski diffusion relation D=ukBTc provides a connection to Tc.
