Weak localization and magnetoconductance in percolative superconducting aluminum films

Kazumasa Yamada; Bunjyu Shinozaki; Takashi Kawaguti

doi:10.1103/PhysRevB.70.144503

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Weak localization and magnetoconductance in percolative superconducting aluminum films

Kazumasa Yamada, Bunjyu Shinozaki, Takashi Kawaguti

DOI 10.1103/PhysRevB.70.144503 · Physical Review B

T1

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Abstract

In order to investigate the crossover from a homogeneous behavior to an inhomogeneous (percolative) one, the temperature T and magnetic field H dependence of the sheet resistance R◻ have been measured for two-dimensional granular aluminum films. Fitting the theory to data on magnetoconductance near TC with use of the diffusion constant D(T) as a fitting parameter, we have obtained the anomalous T-dependent diffusion constant D. From D(T), the electron diffusion index θ, a certain critical exponent in the percolation theory, has been obtained. In the relation R◻−θ, the value of θ varies abruptly near 1.5kΩ. This behavior suggests the abovementioned crossover is similar to our previous results determined from the T dependence of the upper critical magnetic field. For percolative films at H=5T, we have found the strong R◻ dependence of the prefactor αT in the expression σ=[αTe2∕(2π2ℏ)]lnT+σ0. The relation αT∝1∕R◻ can be explained qualitatively by a model of scaling law for percolation.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Al Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.81	Pressure not reported	unknown