Anomalous metals: From "failed superconductor" to "failed insulator"

Xinyang Zhang, Alexander Palevski, Aharon Kapitulnik

Research output: Contribution to journalArticlepeer-review


Resistivity saturation is found on both superconducting and insulating sides of an "avoided"magnetic-field-tuned superconductor-to-insulator transition (H-SIT) in a two-dimensional In/InOx composite, where the anomalous metallic behavior cuts off conductivity or resistivity divergence in the zero-temperature limit. The granular morphology of the material implies a system of Josephson junctions (JJs) with a broad distribution of Josephson coupling EJ and charging energy EC, with an H-SIT determined by the competition between EJ and EC . By virtue of self-duality across the true H-SIT, we invoke macroscopic quantum tunneling effects to explain the temperatureindependent resistance where the "failed superconductor"side is a consequence of phase fluctuations and the "failed insulator"side results from charge fluctuations. While true self-duality is lost in the avoided transition, its vestiges are argued to persist, owing to the incipient duality of the percolative nature of the dissipative path in the underlying random JJ system.

Original languageEnglish
Article numbere2202496119
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number29
StatePublished - 19 Jul 2022


  • anomalous metals
  • Josephson junction array
  • quantum fluctuations
  • self-duality


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