Abstract
Ultrathin films near the quantum insulator-superconductor transition (IST) can exhibit Cooper-pair transport in their insulating state. This Cooper-pair insulator (CPI) state is achieved in amorphous Bi films evaporated onto substrates with a topography varying on lengths slightly greater than the superconducting coherence length. We present evidence that this topography induces film thickness and corresponding superconducting coupling constant variations that promote Cooper-pair island formation. Analyses of many thickness-tuned ISTs show that weak links between superconducting islands dominate the transport. In particular, the IST occurs when the link resistance approaches the resistance quantum for pairs. These results support conjectures that the CPI is an inhomogeneous state of matter.
Department
Physics
Publication Date
8-25-2011
Journal Title
Physical Review B
Publisher
American Physical Society
Digital Object Identifier (DOI)
10.1103/PhysRevB.84.064528
Document Type
Article
Recommended Citation
S. M. Hollen, H. Q. Nguyen, E. Rudisaile, M. D. Stewart, J. Shainline, J. M. Xu, and J. M. Valles, ‘Cooper-pair insulator phase in superconducting amorphous bi films induced by nanometer-scale thickness variations’, Physical Review B, vol. 84, no. 6, Aug. 2011.
Rights
©2011 American Physical Society