TY  - JOUR
AU  - Lyatti, M.
AU  - Gundareva, I.
AU  - Röper, T.
AU  - Popović, Z.
AU  - Jalil, A. R.
AU  - Grützmacher, D.
AU  - Schäpers, T.
TI  - Quantum size effects in ultra-thin YBa2Cu3O7 − x films
JO  - Scientific reports
VL  - 14
IS  - 1
SN  - 2045-2322
CY  - [London]
PB  - Macmillan Publishers Limited, part of Springer Nature
M1  - FZJ-2024-06592
SP  - 22174
PY  - 2024
AB  - The d-wave symmetry of the order parameter with zero energy gap in nodal directions stands in the way of using high-temperature superconductors for quantum applications. We investigate the symmetry of the order parameter in ultra-thin YBa2Cu3O7 − x (YBCO) films by measuring the electrical transport properties of nanowires aligned at different angles relative to the main crystallographic axes. The anisotropy of the nanowire critical current in the nodal and antinodal directions reduces with the decrease in the film thickness. The Andreev reflection spectroscopy of the nanoconstrictions shows the presence of a thickness-dependent energy gap that does not exist in bulkYBCO. We find that thethickness-dependent energy gap appears due to the quantum size effects in ultra-thinYBCO films that open the energy gap along the entire Fermi surface. The fully gapped state of the ultra-thin YBCO films makes them a promising platform for quantum applications, including quantum computing and quantum communications.
LB  - PUB:(DE-HGF)16
C6  - 39333745
UR  - <Go to ISI:>//WOS:001354536300279
DO  - DOI:10.1038/s41598-024-73207-z
UR  - https://juser.fz-juelich.de/record/1033741
ER  -