Transport regimes in tunnel ferromagnetic Josephson junctions

Abstract

We present a systematic study of the temperature-dependent transport properties of Nb- and Al-based superconductor--insulator--thin superconductor--ferromagnet--superconductor (SIsFS) Josephson junctions. By varying the superconducting material and the thickness of the intermediate superconducting layer, we identify three distinct transport regimes: a tunnel-dominated SIS-like regime, a temperature-driven crossover, and a complex weak-link regime. A unified Usadel-based description connects these regimes through the self-consistent pair potential of the intermediate s-layer. While for Al-based devices an SIS-like transport regime is observed, a self-consistent calculation of the s/F/S proximity electrode, combined with perturbative tunnel coupling to the outer electrode, accounts for Nb devices with different thickness of the superconducting interlayer. The calculation places the 10-nm-interlayer sample in a proximity-supported, strongly suppressed s state, close to the SInFS limit in which the interlayer is effectively driven normal (\textit{n}). A reduced nonlinear long-junction description captures the same limiting physics. The evolution of I_cR_N(T) thereby provides a direct experimental signature of the three transport regimes. Beyond the fundamental interest, the results establish practical design guidelines: Nb junctions with sufficiently thick s interlayers are well suited for high-speed cryogenic memory elements and tunable superconducting parametric amplifiers, while Al junctions are natural candidates for coherent superconducting quantum circuits

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BibTeX RIS

BibTeX

@misc{satariano2026transport,
  title = {{Transport regimes in tunnel ferromagnetic Josephson junctions}},
  author = {R. Satariano and A. A. Golubov and E. Raja and R. Ferraiuolo and F. Calloni and H. G. Ahmad and A. Vettoliere and N. Poccia and L. Parlato and G. Ausanio and C. Granata and G. P. Pepe and M. Yu. Kupriyanov and F. Tafuri and D. Montemurro and D. Massarotti},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.20268},
  eprint = {2610.20268},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.20268},
  note = {CC BY-NC-ND 4.0},
}

RIS

TY  - UNPB
TI  - Transport regimes in tunnel ferromagnetic Josephson junctions
AU  - R. Satariano
AU  - A. A. Golubov
AU  - E. Raja
AU  - R. Ferraiuolo
AU  - F. Calloni
AU  - H. G. Ahmad
AU  - A. Vettoliere
AU  - N. Poccia
AU  - L. Parlato
AU  - G. Ausanio
AU  - C. Granata
AU  - G. P. Pepe
AU  - M. Yu. Kupriyanov
AU  - F. Tafuri
AU  - D. Montemurro
AU  - D. Massarotti
PY  - 2026
DA  - 2026/10/14
PB  - arXiv
DO  - 10.48550/arxiv.2610.20268
UR  - https://arxiv.org/abs/2610.20268
AB  - We present a systematic study of the temperature-dependent transport properties of Nb- and Al-based superconductor--insulator--thin superconductor--ferromagnet--superconductor (SIsFS) Josephson junctions. By varying the superconducting material and the thickness of the intermediate superconducting layer, we identify three distinct transport regimes: a tunnel-dominated SIS-like regime, a temperature-driven crossover, and a complex weak-link regime. A unified Usadel-based description connects these regimes through the self-consistent pair potential of the intermediate s-layer. While for Al-based devices an SIS-like transport regime is observed, a self-consistent calculation of the s/F/S proximity electrode, combined with perturbative tunnel coupling to the outer electrode, accounts for Nb devices with different thickness of the superconducting interlayer. The calculation places the 10-nm-interlayer sample in a proximity-supported, strongly suppressed s state, close to the SInFS limit in which the interlayer is effectively driven normal (\textit{n}). A reduced nonlinear long-junction description captures the same limiting physics. The evolution of I_cR_N(T) thereby provides a direct experimental signature of the three transport regimes. Beyond the fundamental interest, the results establish practical design guidelines: Nb junctions with sufficiently thick s interlayers are well suited for high-speed cryogenic memory elements and tunable superconducting parametric amplifiers, while Al junctions are natural candidates for coherent superconducting quantum circuits
ER  -

Abstract

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