Nb-based Josephson junctions have been fabricated, which can select one of two states depending on the relative magnetization of their ferromagnetic barrier layers. To minimize the free-layer switching energy, while maintaining adequate thermal stability at 4.2 K, a dilute Cu-permalloy alloy [Cu 0.7(Ni80Fe20)0.3] with a low magnetic saturation (Ms ∼ 80 emu/cm3) is used. The optimal thickness of the permalloy (Ni80Fe20) fixed-layer is shown to be 2.4 nm. Such devices exhibit switching at magnetic fields as low as 5 Oe, demonstrating their potential use in low power non-volatile memory for superconductor digital circuits.

Original languageEnglish (US)
Article number022602
JournalApplied Physics Letters
Issue number2
StatePublished - Jan 13 2014

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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