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TT: Fachverband Tiefe Temperaturen

TT 6: Superconductivity: Tunnelling and Josephson Junctions I

TT 6.5: Talk

Monday, March 18, 2024, 10:30–10:45, H 3010

Equal-spin Cooper pairs across S/M interfaces with strongly polarized magnets — •Danilo Nikolic and Matthias Eschrig — Institut für Physik, Universität Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald, Germany

Motivated by recent experiments on the proximity effect in the superconductor (S) - helimagnet (M) systems [1], we present a systematic theoretical study of such an effect in SM systems with strongly polarized M featuring different textures of magnetization. The theory is done in the framework of the quasiclassical Usadel Green’s formalism. However, due to the large splitting between the spin bands, the standard Usadel approach [2] cannot be applied directly but a somewhat modified description is required [3]. Applying this approach, we account for equal-spin triplet correlations and investigate their influence on observables, e.g., the critical temperature of S. Moreover, due to the strong spin polarization of M, Josephson junctions involving it represent a promising platform for studying the novel superconducting diode effect. This effect can be explained through the coupling between the superconducting phase and the gauge field induced by the inhomogeneous magnetization in M [4].

[1] A. Spuri et al., arXiv:2305.02216 (2023)

[2] A. I. Buzdin, Rev. Mod. Phys. 77 (2005) 935

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

[4] A. B. Vorontsov et al., Phys. Rev. Lett. 101 (2008) 127003; I. V. Bobkova et al., Phys. Rev. B 96 (2017) 094506

Keywords: Proximity effect; Superconducting spintronics; Spin-triplet superconductivity; Josephson current; Diode effect