Transport and magnetization dynamics in a superconductor/single-molecule magnet/superconductor junction

Abstract

We study dc-transport and magnetization dynamics in a junction of arbitrary transparency consisting of two spin-singlet superconducting leads connected via a single classical spin precessing at the frequency $\Omega$. The presence of the spin in the junction provides different transmission amplitudes for spin-up and spin-down quasiparticles as well as a time-dependent spin-flip transmission term. For a phase biased junction, we show that a steady-state superconducting charge current flows through the junction and that an out-of-equilibrium circularly polarized spin current, of frequency $\Omega$, is emitted in the leads. Detailed understanding of the charge and spin currents is obtained in the entire parameter range. In the adiabatic regime, $\hslash \Omega \ll 2\Delta$ where $\Delta$ is the superconducting gap, and for high transparencies of the junction, a strong suppression of the current takes place around $\vp \approx 0$ due to an abrupt change in the occupation of the Andreev bound-states. At higher values of the phase and/or precession frequency, extended (quasi-particle like) states compete with the bound-states in order to carry the current. Well below the superconducting transition, these results are shown to be weakly affected by the back-action of the spin current on the dynamics of the precessing spin. Indeed, we show that the Gilbert damping due to the quasi-particle spin current is strongly suppressed at low-temperatures, which goes along with a shift of the precession frequency due to the condensate. The results obtained may be of interest for on-going experiments in the field of molecular spintronics.

19 pages, 13 figures (v3) Minor modifications per referee's comments. No change in results. (v2) 2 authors added, 1 reference added (Ref. 25), no change in the text and results

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Cited by in corpus (15)

• Superconducting Spintronics
• Spin Supercurrent, Magnetization Dynamics, and Phi-State in Spin-Textured Josephson Junctions
• Interaction of a Nanomagnet with a Weak Superconducting Link
• Resistive state of SFS Josephson junctions in the presence of moving domain walls
• Non-equilibrium effects in a Josephson junction coupled to a precessing spin
• Spin pumping between noncollinear ferromagnetic insulators through thin superconductors
• Spin-polarized Shapiro steps and spin-precession-assisted multiple Andreev reflection
• Spin-precession-assisted supercurrent in a superconducting quantum point contact coupled to a single-molecule magnet
• Spin transport and tunable Gilbert damping in a single-molecule magnet junction
• Josephson current through a quantum dot coupled to a molecular magnet
• Non-linear spin torque, pumping and cooling in superconductor/ferromagnet systems
• Dynamical torques from Shiba states in $s$-wave superconductors
• Magnetic resonance in a singlet-triplet Josephson junction
• Spin nutation effects in molecular nanomagnet$-$superconductor tunnel junctions
• Spin transport through a nanojunction with a precessing anisotropic molecular spin: Quantum interference and spin-transfer torque