Imaging the Current Distribution in Superconducting Transition-Edge Sensors with Scanning SQUID Microscopy

@misc{walker2026imaging,
  title = {{Imaging the Current Distribution in Superconducting Transition-Edge Sensors with Scanning SQUID Microscopy}},
  author = {Samantha Walker and Austin Kaczmarek and Douglas A. Bennett and Jason E. Austermann and W. Bertrand Doriese and Shannon M. Duff and Johannes Hubmayr and Kelsey M. Morgan and Daniel R. Schmidt and Daniel S. Swetz and Joel N. Ullom and Joel Weber and Michael D. Niemack and Katja C. Nowack},
  howpublished = {arXiv},
  year = {2026},
  month = nov,
  doi = {10.48550/arxiv.2611.02352},
  eprint = {2611.02352},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2611.02352},
}

TY  - UNPB
TI  - Imaging the Current Distribution in Superconducting Transition-Edge Sensors with Scanning SQUID Microscopy
AU  - Samantha Walker
AU  - Austin Kaczmarek
AU  - Douglas A. Bennett
AU  - Jason E. Austermann
AU  - W. Bertrand Doriese
AU  - Shannon M. Duff
AU  - Johannes Hubmayr
AU  - Kelsey M. Morgan
AU  - Daniel R. Schmidt
AU  - Daniel S. Swetz
AU  - Joel N. Ullom
AU  - Joel Weber
AU  - Michael D. Niemack
AU  - Katja C. Nowack
PY  - 2026
DA  - 2026/11/02
PB  - arXiv
DO  - 10.48550/arxiv.2611.02352
UR  - https://arxiv.org/abs/2611.02352
AB  - Transition-edge sensors (TESs) exploit the resistive transition of a superconductor to detect minute changes in temperature. While significant progress has been made in understanding the temperature- and current-dependent resistive transition in these devices, important aspects of TES behavior under bias remain unresolved. In particular, existing TES models largely neglect spatial variations in the superconducting state and current distribution arising from device geometry and proximity effects associated with the superconducting leads and normal metal features. Using scanning superconducting quantum interference device (SQUID) microscopy (SSM), we directly image local superconducting properties and transport current in two molybdenum-gold (MoAu) X-ray TES designs. We measure the local diamagnetic response to identify superconducting regions in devices voltage-biased within the transition and the Oersted field generated by the transport current to reconstruct the corresponding current distribution. We observe bias-dependent reconfigurations of the current distribution that track current-induced changes in superconducting regions, highlighting the importance of mesoscale spatial variations for TES device physics, operation, and design.
ER  -