Superconducting weak links at substrate steps in bilayer nickelate films
Abstract
Ambient-pressure superconductivity above 40 K has been realized in bilayer nickelate thin films on SrLaAlO4 (001), yet resistive measurements often exhibit incomplete zero-resistance states and/or two-step superconducting transitions of unresolved origin. We show that these features arise from superconducting weak links at substrate step-terrace structures. A direct correlation between the azimuthal-angle-dependent two-step transition and step-terrace orientation establishes this connection, further supported by atomic-scale visualization of structurally disrupted regions at step terraces. Modeling the films as pristine (weak-link) regions with higher (lower) transition temperature reproduces essential features of the two-step transition using both a simple model and finite-element simulations. Transport measurements further reveal a strong dependence of transition characteristics - and even the occurrence of superconductivity itself - on average terrace width. These results identify step-induced weak links as the microscopic origin of two-step transitions in bilayer nickelate films, providing a framework for understanding anisotropic and percolative transport, and a route to superconducting devices.
Versions
Related
- Selective suppression of electronic orders via interlayer coupling in superconducting bilayer nickelate thin films
- Spectroscopic evidence of competing diagonal spin interactions and spin disproportionation in the bilayer nickelate La 3 Ni 2 O 7
- Observation of superconductivity-induced leading-edge gap in a bilayer nickelate
- Direct imaging of the Ni eg hole orbitals in the bilayer nickelate La2SmNi2O7
- Electronic theory for scanning tunneling microscopy spectra in bilayer nickelate thin films
BibTeX
@misc{liu2026superconducting,
title = {{Superconducting weak links at substrate steps in bilayer nickelate films}},
author = {Yidi Liu and Yaoju Tarn and Lopa Bhatt and Puhua Zhang and Joonseo Song and Berit H. Goodge and David A. Muller and Harold Y. Hwang and Yijun Yu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.27729},
eprint = {2610.27729},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.27729},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Superconducting weak links at substrate steps in bilayer nickelate films
AU - Yidi Liu
AU - Yaoju Tarn
AU - Lopa Bhatt
AU - Puhua Zhang
AU - Joonseo Song
AU - Berit H. Goodge
AU - David A. Muller
AU - Harold Y. Hwang
AU - Yijun Yu
PY - 2026
DA - 2026/10/20
PB - arXiv
DO - 10.48550/arxiv.2610.27729
UR - https://arxiv.org/abs/2610.27729
AB - Ambient-pressure superconductivity above 40 K has been realized in bilayer nickelate thin films on SrLaAlO_4 (001), yet resistive measurements often exhibit incomplete zero-resistance states and/or two-step superconducting transitions of unresolved origin. We show that these features arise from superconducting weak links at substrate step-terrace structures. A direct correlation between the azimuthal-angle-dependent two-step transition and step-terrace orientation establishes this connection, further supported by atomic-scale visualization of structurally disrupted regions at step terraces. Modeling the films as pristine (weak-link) regions with higher (lower) transition temperature reproduces essential features of the two-step transition using both a simple model and finite-element simulations. Transport measurements further reveal a strong dependence of transition characteristics - and even the occurrence of superconductivity itself - on average terrace width. These results identify step-induced weak links as the microscopic origin of two-step transitions in bilayer nickelate films, providing a framework for understanding anisotropic and percolative transport, and a route to superconducting devices.
ER -