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TT: Fachverband Tiefe Temperaturen
TT 55: Superconductivity: Tunnelling and Josephson Junctions
TT 55.1: Hauptvortrag
Donnerstag, 19. März 2020, 09:30–10:00, HSZ 204
Probing Triplet Superconductivity by Scanning Tunneling Spectroscopy — Simon Diesch1, Peter Machon1, Michael Wolz1, Christoph Sürgers2, Detlef Beckmann3, Wolfgang Belzig1, and •Elke Scheer1 — 1Physics Department, University of Konstanz, Konstanz, Germany — 2Physical Institute, KIT, Karlsruhe, Germany — 3Institute for Nanotechnology, KIT, Karlsruhe, Germany
In this talk we address the proximity effect between a superconductor (S) and a normal metal (N) linked by a spin-active interface. With the help of a low-temperature scanning tunneling microscope we study the local density of states of trilayer systems consisting of Al (S), the ferromagnetic insulator EuS, and the noble metal Ag (N). In several recent studies it has been shown that EuS acts as ferromagnetic insulator with well-defined magnetic properties down to very low thickness [1]. We observe pronounced subgap structures that either reveal a zero-bias peak (ZBP) or an additional zero-bias splitting (ZBS) and that can be tuned by a magnetic field. We interpret our findings in the light of recent theories of odd-triplet contributions created by the spin-active interface [2,3]. In particular, we discuss that the ZBS is a hallmark for spin-polarized triplet pairs, able to carry long-ranged supercurrents into F, while the ZBP is a signature for short-ranged, mixed-spin triplet pairs.
[1] S. Diesch et al., Nature Commun. 9, 5248 (2018)
[2] B. Li et al., Phys. Rev. Lett. 110, 09700 (2013)
[3] A. Cottet et al., Phys. Rev. B 80, 184511 (2009)