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We have grown and characterized (110)-oriented YBa2Cu3O7−x (YBCO)/PrBa2(Cu0.8Ga0.2)3O7−x (PBCGO) bilayer and YBCO/PBCGO/YBCO trilayer heterostructures, which were deposited by pulsed laser deposition technique for the nanofabrication of (110)-oriented YBCO-based superconductor (S)/insulator (I)/superconductor (S) tunneling vertical geometry Josephson junction and other superconductor electronic devices. The structural properties of these heterostructures, investigated through various x-ray diffraction techniques (profile, x-ray reflectivity, pole figure, and reciprocal mapping), showed (110)-oriented epitaxial growth with a preferred c-axis-in-plane direction for all layers of the heterostructures. The atomic force microscopy measurement on the top surface of the heterostructures showed crack-free and pinhole-free, compact surface morphology with about a few nanometer root mean square roughness over the 5 × 5 μm2 region. The electrical resistivity measurements on the (110)-direction of the heterostructures showed superconducting critical temperature (Tc) values above 77 K and a very small proximity effect due to the interfacial contact of the superconducting YBCO layers with the PBCGO insulating layer. Raman spectroscopy measurements on the heterostructures showed the softening of the Ag-type Raman modes associated with the apical oxygen O(4) and O(2)-O(3)-in-phase vibrations compared to the stand-alone (110)-oriented PBCGO due to the residual stress and additional two Raman modes at ∼600 and ∼285 cm−1 frequencies due to the disorder at the Cu–O chain site of the PBCGO. The growth process and structural, electrical transport, and Raman spectroscopy characterization of (110)-oriented YBCO/PBCGO bilayer and YBCO/PBCGO/YBCO trilayer heterostructures are discussed in detail.
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This content will become publicly available on August 5, 2026
Nonvanishing Eliashberg gap function in YBa2Cu3O7 above Tc
This paper presents the numerical solution of the temperature dependent Eliashberg gap equations on the real axis for anisotropic superconductor YBa2Cu3O7 (YBCO) for below and above the calculated Tc. In those numerical calculations, the results of the first-principles electronic structure of YBCO were integrated into the Eliashberg gap equations based on the theory of many-body physics for superconductivity. As demonstrated previously,[1] the calculated Tc for YBCO was about 89 K for μ* = 0.1, which was quite close to that of experimental observations. For T < Tc, there is a large anisotropy of superconducting gap on the Fermi surface of YBCO.[2,3] Furthermore, above Tc, such as 105 K, it was found that the real part of gap function is not zero at finite frequency, although for the frequency near 0, the real part of gap function is zero. The results may be used to understand some pseudogap state properties in the material.
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- Award ID(s):
- 2216805
- PAR ID:
- 10629145
- Editor(s):
- Coniglio, Gabriele
- Publisher / Repository:
- Elsevier B.V
- Date Published:
- Journal Name:
- Physics Open
- Volume:
- 25
- Issue:
- C
- ISSN:
- 2666-0326
- Page Range / eLocation ID:
- 100304
- Subject(s) / Keyword(s):
- First-principles calculation YBa2Cu3O7 Gap function Pseudogap state
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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