Critical current fluctuations in graphene Josephson junctions

Mohammad T. Haque*, Marco Will, Matti Tomi, Preeti Pandey, Manohar Kumar, Felix Schmidt, Kenji Watanabe, Takashi Taniguchi, Romain Danneau, Gary Steele, Pertti Hakonen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

We have studied 1/f noise in critical current Ic in h-BN encapsulated monolayer graphene contacted by NbTiN electrodes. The sample is close to diffusive limit and the switching supercurrent with hysteresis at Dirac point amounts to ≃ 5 nA. The low frequency noise in the superconducting state is measured by tracking the variation in magnitude and phase of a reflection carrier signal vrf at 600–650 MHz. We find 1/f critical current fluctuations on the order of δIc/ Ic≃ 10 - 3 per unit band at 1 Hz. The noise power spectrum of critical current fluctuations SIc measured near the Dirac point at large, sub-critical rf-carrier amplitudes obeys the law SIc/Ic2=a/fβ where a≃ 4 × 10 - 6 and β≃ 1 at f> 0.1 Hz. Our results point towards significant fluctuations in Ic originating from variation of the proximity induced gap in the graphene junction.

Original languageEnglish
Article number19900
Number of pages10
JournalScientific Reports
Volume11
Issue number1
DOIs
Publication statusPublished - 6 Oct 2021
MoE publication typeA1 Journal article-refereed

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