English

Large critical current density Josephson $\pi$ junctions with PdNi barriers

Superconductivity 2026-03-26 v2 Mesoscale and Nanoscale Physics

Abstract

We report large π\pi-state critical current densities, Jc(π)J_c(\pi), in Nb/Pd89_{89}Ni11_{11}/Nb Josephson junctions at Pd89_{89}Ni11_{11} thicknesses near the first π\pi-state. We observe oscillations in the critical current with ferromagnetic barrier thickness consistent with a 00-π\pi transition. For a junction with a 9.4~nm Pd89_{89}Ni11_{11} barrier, we obtain Jc(π)=410 kA/cm2J_c(\pi) = 410~\mathrm{kA/cm^{2}} at 4.2~K, exceeding values reported in prior PdNi-based studies. Magnetization measurements on continuous films, together with coercivity tests on patterned arrays, confirm that Pd89_{89}Ni11_{11} exhibits perpendicular magnetic anisotropy, enabling zero-field operation without magnetic initialization. The combination of large Jc(π)J_c(\pi) and intrinsic anisotropy establishes Pd89_{89}Ni11_{11} as a promising barrier material for passive π\pi-shifters in superconducting digital logic and qubit architectures.

Keywords

Cite

@article{arxiv.2505.03913,
  title  = {Large critical current density Josephson $\pi$ junctions with PdNi barriers},
  author = {Arjun Sapkota and Pukar Sedai and Robert M. Klaes and Reza Loloee and Norman O. Birge and Nathan Satchell},
  journal= {arXiv preprint arXiv:2505.03913},
  year   = {2026}
}

Comments

7 pages, 5 figures

R2 v1 2026-06-28T23:23:36.908Z