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arXiv · 2007.15569

Temperature-dependent spin-transport and current-induced torques in superconductor/ferromagnet heterostructures

Manuel Müller·Lukas Liensberger·Luis Flacke·Hans Huebl·Akashdeep Kamra·Wolfgang Belzig·Rudolf Gross·Mathias Weiler·Matthias Althammer
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Abstract

We investigate the injection of quasiparticle spin currents into a superconductor via spin pumping from an adjacent FM layer.$\;$To this end, we use NbN/\ch{Ni80Fe20}(Py)-heterostructures with a Pt spin sink layer and excite ferromagnetic resonance in the Py-layer by placing the samples onto a coplanar waveguide (CPW). A phase sensitive detection of the microwave transmission signal is used to quantitatively extract the inductive coupling strength between sample and CPW, interpreted in terms of inverse current-induced torques, in our heterostructures as a function of temperature. Below the superconducting transition temperature $T_{\mathrm{c}}$, we observe a suppression of the damping-like torque generated in the Pt layer by the inverse spin Hall effect (iSHE), which can be understood by the changes in spin current transport in the superconducting NbN-layer. Moreover, below $T_{\mathrm{c}}$ we find a large field-like current-induced torque.

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Manuel Müller, Lukas Liensberger, Luis Flacke, Hans Huebl, Akashdeep Kamra, Wolfgang Belzig, Rudolf Gross, Mathias Weiler, Matthias Althammer. 2020-07-30. Temperature-dependent spin-transport and current-induced torques in superconductor/ferromagnet heterostructures. https://doi.org/10.1103/physrevlett.126.087201

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