We have over 12,000 students, from over 100 countries, within one of the safest campuses in the UK


97% of Lancaster students go into work or further study within six months of graduating

Home > Research > Publications & Outputs > Large-scale superconductivity-induced conductan...
View graph of relations

« Back

Large-scale superconductivity-induced conductance suppression in mesoscopic normal-superconducting structures

Research output: Contribution to journalJournal article


<mark>Journal publication date</mark>05/1999
<mark>Journal</mark>Superlattices and Microstructures
Number of pages7
<mark>Original language</mark>English


Experiments on hybrid superconducting normal-metal structures have revealed that even in the absence of tunnel junctions the onset of superconductivity can lead to a decrease in the electrical conductance by an amount many orders of magnitude greater than e(2)/h. In this paper, we provide a theory of this phenomenon which shows that it originates from an instability in the four-probe conductance which is absent from two-probe measurements. We compare the zero-bias, zero-temperature four-probe conductances GN and Gs of a normal diffusive metal in contact with a superconductor in both the normal (N) and superconducting (S) states, respectively. In the absence of tunnel barriers, the ensemble average of the difference delta G = G(S) - G(N) vanishes, in agreement with quasiclassical theory. However, we also predict that there exist macroscopic sample specific fluctuations in delta G, which lie beyond quasiclassical theory and allow large negative values of 6G to occur. (C) 1999 Academic Press.