Tunneling in and the microstructure of granular superconductors

D. S. McLachlan*, R. Rosenbaum

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review


The microstructure of granular superconductors are discussed and the difference between granular and random composites is noted. The model where a granular (and a random) superconductor, close to the percolation threshold, is considered to be made up of large granular dusters, linked by tunnelling junctions or weak links, is introduced. This model is illustrated using recent experimental measurements on nanostructured granular Al-Ge. The measurements dearly show that the coupling junctions between clusters can, depending on the volume fraction of superconductor, be of either a Josephson or quasi-particle nature, or a combination of both. The differences between a granular and a dirty superconductor and the upper critical field of granular superconductors is then discussed and it is shown that the diameter of the grains can be estimated from the upper critical field. Random Al-Ge, which has a rather different microstructure, is also discussed.

Original languageEnglish
Pages (from-to)321-326
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
StatePublished - 1996
Externally publishedYes
EventProceedings of the 1995 MRS Fall Meeting - Boston, MA, USA
Duration: 26 Nov 19951 Dec 1995


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