Superconducting and insulating behaviour in granular aluminum oxide nanowires

Granular aluminum oxide (AlOx) nanowires are a promising alternative to Josephson tunnel junctions as a nonlinear element in superconducting quantum circuits. Due to the internal structure, the sheet resistance of this... [ view full abstract ]

Granular aluminum oxide (AlOx) nanowires are a promising alternative to Josephson tunnel junctions as a nonlinear element in superconducting quantum circuits. Due to the internal structure, the sheet resistance of this material can be adjusted over a wide kOhm range [1].

Due to the high flexibility of this approach, we employ an electron beam lithography nano-fabrication process, with the intention of being used for highly coherent superconducting quantum circuits. The fabricated 20 nm wide nanowires have a very clean interface to the sapphire substrate and no remaining fabrication residue in the vicinity of the circuit. Experimentally, we explore the phase transition from superconducting to insulating behavior in nanowires with a length span between 50 nm and 1 um.

[1] H. Rotzinger, S. T. Skacel, M. Pfirrmann, J. N. Voss, J. Münzberg, S. Probst, P. Bushev, M. P. Weides, A. V. Ustinov and J. E. Mooij, Supercond. Sci. Technol. 30, 025002 (2016)