AC/DC spin current in ferromagnet/superconductor/normal metal trilayer systems

Fuente: arXiv
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Main Authors: Mizuno, Koki, Ishida, Hirone, Teranishi, Manato
Format: Preprint
Published: 2025
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_version_ 1866912781325828096
author Mizuno, Koki
Ishida, Hirone
Teranishi, Manato
author_facet Mizuno, Koki
Ishida, Hirone
Teranishi, Manato
contents Spin pumping with superconductors has been extensively studied, particularly in double-layer systems. In this study, we investigate spin pumping in a trilayer system comprising a ferromagnetic insulator (FMI), a superconductor (SC), and a normal metal (NM). We derive the AC and DC spin currents in the NM layer induced by spin motion in the FMI under circularly polarized microwave irradiation. If we treat the spin motion as classical, the AC spin current is expressed. On the other hand, if we treat the spin motion as quantum quasiparticles, the DC spin current is derived. After these derivations, while the computational cost of evaluating the spin current is extremely high, we mitigate this using the Quantics Tensor Cross Interpolation (QTCI) method. We present numerical results showing the dependence of the spin current on temperature, microwave frequency, and superconductor layer thickness. Notably, the temperature dependence of AC and DC spin currents exhibits a coherence peak. Furthermore, we have discovered a transition structure in the dependence of the spin current on the thickness of the superconductor layer, where the dependence changes after a particular frequency.
format Preprint
id arxiv_https___arxiv_org_abs_2507_23262
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle AC/DC spin current in ferromagnet/superconductor/normal metal trilayer systems
Mizuno, Koki
Ishida, Hirone
Teranishi, Manato
Superconductivity
Mesoscale and Nanoscale Physics
Computational Physics
Spin pumping with superconductors has been extensively studied, particularly in double-layer systems. In this study, we investigate spin pumping in a trilayer system comprising a ferromagnetic insulator (FMI), a superconductor (SC), and a normal metal (NM). We derive the AC and DC spin currents in the NM layer induced by spin motion in the FMI under circularly polarized microwave irradiation. If we treat the spin motion as classical, the AC spin current is expressed. On the other hand, if we treat the spin motion as quantum quasiparticles, the DC spin current is derived. After these derivations, while the computational cost of evaluating the spin current is extremely high, we mitigate this using the Quantics Tensor Cross Interpolation (QTCI) method. We present numerical results showing the dependence of the spin current on temperature, microwave frequency, and superconductor layer thickness. Notably, the temperature dependence of AC and DC spin currents exhibits a coherence peak. Furthermore, we have discovered a transition structure in the dependence of the spin current on the thickness of the superconductor layer, where the dependence changes after a particular frequency.
title AC/DC spin current in ferromagnet/superconductor/normal metal trilayer systems
topic Superconductivity
Mesoscale and Nanoscale Physics
Computational Physics
url https://arxiv.org/abs/2507.23262