Nano Josephson superconducting tunnel junctions in YBa2Cu3O(7-δ) directly patterned with a focused helium ion beam.
Since the discovery of the high-transition-temperature superconductors (HTSs), researchers have explored many methods to fabricate superconducting tunnel junctions from these materials for basic science purposes and applications. HTS circuits operating at liquid-nitrogen temperatures (∼77 K) would significantly reduce power requirements in comparison with those fabricated from conventional superconductors. The difficulty is that the superconducting coherence length is very short and anisotropic in these materials, typically ∼2 nm in the a-b plane and ∼0.2 nm along the c axis. The electrical properties of Josephson junctions are therefore sensitive to chemical variations and structural defects on atomic length scales. To make multiple uniform HTS junctions, control at the atomic level is required. In this Letter we demonstrate all-HTS Josephson superconducting tunnel junctions created by using a 500-pm-diameter focused beam of helium ions to directly write tunnel barriers into YBa2Cu3O(7-δ) (YBCO) thin films. We demonstrate the ability to control the barrier properties continuously from conducting to insulating by varying the irradiation dose. This technique could provide a reliable and reproducible pathway for scaling up quantum-mechanical circuits operating at liquid-nitrogen temperatures, as well as an avenue to conduct novel planar superconducting tunnelling studies for basic science.
1] Oxide Nano Electronics Laboratory, Department of Physics, University of California San Diego, La Jolla, California 92093, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Shane A
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Cybart
Oxide Nano Electronics Laboratory, Department of Physics, University of California San Diego, La Jolla, California 92093, USA.
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Cho
Oxide Nano Electronics Laboratory, Department of Physics, University of California San Diego, La Jolla, California 92093, USA.
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TJ
Wong
Oxide Nano Electronics Laboratory, Department of Physics, University of California San Diego, La Jolla, California 92093, USA.
Björn H
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Wehlin
Oxide Nano Electronics Laboratory, Department of Physics, University of California San Diego, La Jolla, California 92093, USA.
Meng K
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Ma
Carl Zeiss Microscopy, LLC., One Corporation Way, Peabody, Massachusetts 01960, USA.
Chuong
0000000316968617
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Huynh
1] Oxide Nano Electronics Laboratory, Department of Physics, University of California San Diego, La Jolla, California 92093, USA [2] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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Dynes