SKM 2021 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 5: Poster Session: Superconductivity

TT 5.15: Poster

Montag, 27. September 2021, 13:30–16:00, P

Spin torque in a Josephson junction between two superconducting magnetic impurity states — •Fabian Ziesel¹, Ciprian Padurariu¹, Björn Kubala^1,2, and Joachim Ankerhold¹ — ¹ICQ and IQST, Ulm University, Germany — ²Institute of Quantum Technologies, German Aerospace Center (DLR), Ulm, Germany

Superconducting tunneling between spin-polarized Yu-Shiba-Rusinov (YSR) impurity states can be realized using a functionalized mK-STM [1], which can be further developed as a local probe of electronic spins for spintronics applications. Here, we consider a Josephson junction containing two magnetic impurities and show that the Josephson current is spin-dependent and accompanied by a spin torque. The torque acts to align the two impurities either parallel or anti-parallel, depending on the parity of YSR states occupation.

Using standard Green’s functions techniques, we derive the spin-torque and spin-current as function of the superconducting phase difference φ and the relative angle θ between the impurity spins, modeled as classical magnets. Our results are also relevant for recent realizations of double quantum dot superconducting junctions with YSR states [2]. Finally, we provide a discussion on spin dynamics with a possible relevance to spin chains that show topological superconductivity.
[1] H. Huang et al., Nat. Phys. 16, 1227 (2020)
[2] J.C.E. Saldaña et al., Phys. Rev. Lett. 121, 257701 (2018)