Cooper-pair insulator phase in superconducting amorphous Bi films induced by nanometer-scale thickness variations

S. M. Hollen*, H. Q. Nguyen, E. Rudisaile, M. D. Stewart, J. Shainline, J. M. Xu, J. M. Valles

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

28 Citations (Scopus)

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.

Original languageEnglish
Article number064528
JournalPhysical Review B (Condensed Matter and Materials Physics)
Volume84
Issue number6
DOIs
Publication statusPublished - 25 Aug 2011
MoE publication typeA1 Journal article-refereed

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