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TT: Fachverband Tiefe Temperaturen

TT 6: Superconductivity: Tunnelling and Josephson Junctions I

TT 6.7: Talk

Monday, March 18, 2024, 11:00–11:15, H 3010

Spectral and transport properties of spin-filter Josephson junctions — •Niklas L. Schulz, Anna-Izabella Levbarg, Danilo Nikolic, and Matthias Eschrig — Institut für Physik, Universität Greifswald, D-17489 Greifswald, Germany

Recent experiments [1] showed that the supercurrent in spin-filter Josephson junctions [2], which incorporate a ferromagnetic insulating barrier (FI), strongly varies with the barrier’s width and results in a temperature-induced incomplete 0−π transition. Motivated by this, we provide a full theoretical study of an S-FI-S junction within the quasi-classical Usadel theory [3] and investigate spectral and transport properties. We model the FI interface using a scattering matrix approach that effectively enters the quasi-classical theory as boundary conditions allowing to account for various effects arising from the interface [4]. We found temperature-induced 0−π transitions in S-FI-S junctions which depend on the barrier width. Moreover, self-consistent calculations show incomplete 0−π transitions. Finally, such systems represent an intermediate step towards S-FI-F-FI-S junctions, which are expected to exhibit the superconducting diode effect [5] and are subject of ongoing research.

[1] R. Caruso et al, Phys. Rev. Lett. 122, 047002 (2019)

[2] K. Senapati et al, Nat. Mater. 10, 849-852 (2011)

[3] K. D. Usadel, Phys. Rev. Lett. 25, 507 (1970)

[4] M. Eschrig et al, New J. Phys. 17, 083037 (2015)

[5] R. Grein et al, Phys. Rev. Lett. 102, 227005 (2009)

Keywords: Superconducting spintronics; Josephson effect; Spin-filter; Spin-triplet superconductivity; 0-π transition