Ferromagnetic resonance and voltage-induced transport in normal metal-ferromagnet-superconductor trilayers

Hans Joakim Skadsem; Arne Brataas; Jan Martinek; Yaroslav Tserkovnyak

doi:10.1103/PhysRevB.84.104420

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Ferromagnetic resonance and voltage-induced transport in normal metal-ferromagnet-superconductor trilayers

Hans Joakim Skadsem, Arne Brataas, Jan Martinek, Yaroslav Tserkovnyak

DOI 10.1103/PhysRevB.84.104420 · Physical Review B

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Abstract

We study the subgap spin and charge transport in normal metal-ferromagnet-superconductor trilayers induced by bias voltage and/or magnetization precession. Transport properties are discussed in terms of time-dependent scattering theory. We assume the superconducting gap is small on the energy scales set by the Fermi energy and the ferromagnetic exchange splitting and compute the nonequilibrium charge and spin current response to first order in precession frequency, in the presence of a finite applied voltage. We find that the voltage-induced instantaneous charge current and longitudinal spin current are unaffected by the precessing magnetization, while the pumped transverse spin current is determined by spin-dependent conductances and details of the electron-hole scattering matrix. A simplified expression for the transverse spin current is derived for structures where the ferromagnet is longer than the transverse spin coherence length.