Diamagnetic susceptibility and current distributions in granular superconductors at percolation
| Autor: | Henning Arendt Knudsen, Alex Hansen |
|---|---|
| Rok vydání: | 2000 |
| Předmět: | |
| Zdroj: | Physical Review B. 61:11336-11339 |
| ISSN: | 1095-3795 0163-1829 |
| DOI: | 10.1103/physrevb.61.11336 |
| Popis: | We study a two-dimensional granular superconducting network at the percolation threshold under the influence of an external perpendicular magnetic field. By numerical simulations on the full nonlinear problem, we determine the scaling exponent for the magnetic susceptibility. Further, we report on the scaling properties of the current distribution. The scaling of the current is found to be independent of the value of the magnetic field. Our results are in contradiction with previous numerical results based on linearized equations. We find a value for the susceptibility exponent which does not agree with existing theoretical suggestions, but agrees perfectly with renormalization-group calculations. Superconducting networks have been subject to investigation in various topologies and approximations over the years. The granular superconducting network at the percolation threshold is the main concern of this text. In such a system under the influence of an external magnetic field, the scaling of the magnetic susceptibility obeys a power law. There exist two theoretical predictions for the value of the scaling exponent. 1,2 Previously numerical work has been done in order to decide which theoretical prediction is correct. 3,4 This work was approximate due to linearizations of the governing equations. We demonstrate in this paper that numerical work on the nonlinear equations give different current distributions in the network. There exists further an estimate for the scaling exponent of the susceptibility based on renormalizationgroup calculations. 5 Our simulations provide a value for this exponent that differs from the two theoretical suggestions, but agrees with the renormalization-group estimate. Attemps to compare with experimental result have been made, but they were not conclusive in favor of any theoretical |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|