% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@INPROCEEDINGS{Gundareva:1022156,
      author       = {Gundareva, Irina and Martinez, Jose and Tautz, Frank Stefan
                      and Grützmacher, Detlev and Schäpers, Thomas and Lyatti,
                      Matvey},
      title        = {{A}u/{YB}a2{C}u3{O}7-x heterostructures for microwave
                      applications},
      reportid     = {FZJ-2024-01277},
      year         = {2023},
      abstract     = {Hybrid devices made of 1D or 2D emerging materials and
                      superconducting electrodes are highly relevant both for many
                      applications including quantum technologies and fundamental
                      research [1,2]. Being an integral part of these devices,
                      superconducting electrodes allow the macroscopic quantum
                      state to appear. Usually, these electrodes have been
                      fabricated using low-temperature superconductors but an
                      induced superconducting gap for these structures is rather
                      small and typically has μeV scale. An alternative approach
                      using high-temperature (high-Tc) superconductors is very
                      promising because they possess much larger energy gaps and
                      can be much more stable to external interferences [3]. Until
                      recent times, only several attempts to use high-Tc
                      superconducting electrodes for hybrid devices were made.
                      Conventional high-Tc superconducting electrodes are based on
                      films where the c-axis is normal and the CuO2 planes are
                      parallel to the film surface, providing a relatively low
                      induced energy gap [4].In our work, we employed vicinal
                      substrates to produce the (YBCO) electrodes, where the CuO2
                      planes have direct access to the film surface. For better
                      compatibility with proximitized materials, we capped YBCO
                      film with a gold layer deposited in situ. Having fabricated
                      Au/YBCO heterostructures, we investigated their properties
                      with scanning tunneling microscopy and observed a large
                      energy gap of around 20 meV at the surface of the gold film.
                      The experimental results are in good agreement with the
                      theoretical estimates based on the calculated value of the
                      coherence length in gold. To study the microwave properties
                      of the Au/YBCO electrodes, we fabricated nanoconstrictions
                      with widths from 30 to 500 nm and measured their response to
                      the external monochromatic radiation with a frequency of
                      15-94 GHz in the 60-77.4 K temperature range. The critical
                      current of the nanoconstriction oscillates with the
                      increasing power of the external radiation. The differential
                      resistance of the representative nanoconstriction at a
                      temperature T = 77.4 K with a critical current completely
                      suppressed by 17.6 GHz monochromatic radiation is shown in
                      Figure 1. The Shapiro-like steps are clearly visible up to a
                      voltage bias of 0.8 mV giving evidence of the frequency
                      synchronization of the internal nanoconstriction dynamics by
                      external radiation at frequencies up to 390 GHz. The upper
                      frequency of the synchronization increases up to 650 GHz
                      with the decrease of the temperature down to 60 K. The
                      observation of Shapiro steps induced by 94 GHz monochromatic
                      radiation can be evidence of Josephson dynamics in Au/YBCO
                      nanoconstrictions but not the synchronization of Abrikosov
                      vortices motion.We consider the Au/YBCO electrodes on
                      vicinal substrates to be promising for the hybrid Josephson
                      junctions due to the large induced energy gap at the gold
                      surface and low surface roughness. The microwave response of
                      the Au/YBCO nanoconstriction at frequencies up to 94 GHz
                      confirms that these electrodes can be used for microwave
                      applications.[1] D. Perconte, D. Bercioux, B. Dlubak, P.
                      Seneor, F. S.Bergeret, J. E.Villegas, “Superconducting
                      Proximity Effect in d-Wave Cu-prate/Graphene
                      Heterostructures,” Ann Phys-Berlin, vol. 534, 2100559,
                      2022.[2] E. Prada, P. San-Jose, M. W. A. de Moor, A.
                      Geresdi, E. J. H. Lee, J. Klinovaja, D. Loss, J. Nygard, R.
                      Aguado, L.P. Kouwenhoven “From Andreev to Majorana bound
                      states in hybrid superconductor-semiconductor nanowires,”
                      Nat Rev Phys, vol. 2, pp. 575-594, 2020.[3] J. T. Kao, S.M.
                      Huang, C.Y. Mou, C.C Tsuei, “Tunneling spectroscopy and
                      Majorana modes emergent from topological gapless phases in
                      high-Tc cuprate superconductors,” Phys Rev B, vol. 91, p.
                      134501, 2015.[4] R. Baghdadi, R.Arpaia,S. Charpentier, D.
                      Golubev, T. Bauch, F. Lombardi, “Fabricating Nanogaps in
                      YBa2Cu3O7-d for Hybrid Proximity-Based Josephson
                      Junctions,” Phys Rev Appl,vol 4, p. 014022,2015.},
      month         = {Sep},
      date          = {2023-09-10},
      organization  = {High temperature superconductors in
                       high frequency fields, Giardini Naxos
                       (Italy), 10 Sep 2023 - 13 Sep 2023},
      subtyp        = {After Call},
      cin          = {PGI-9 / PGI-3},
      cid          = {I:(DE-Juel1)PGI-9-20110106 / I:(DE-Juel1)PGI-3-20110106},
      pnm          = {5222 - Exploratory Qubits (POF4-522)},
      pid          = {G:(DE-HGF)POF4-5222},
      typ          = {PUB:(DE-HGF)24},
      doi          = {10.34734/FZJ-2024-01277},
      url          = {https://juser.fz-juelich.de/record/1022156},
}