Spin pumping across ferromagnet/superconductor (F/S) interfaces has attracted much attention lately, yet the focus has been mainly on s-wave superconductor-based systems whereas (high-temperature) d-wave superconductors such as YBa2Cu3O7−d (YBCO) have received scarce attention despite their fundamental and technological interest. Here we use wideband ferromagnetic resonance to study spin-pumping effects in bilayers that combine a soft metallic Ni80Fe20 (Py) ferromagnet and YBCO. We evaluate the spin conductance in YBCO by analyzing the magnetization dynamics in Py. We find that the Gilbert damping exhibits a drastic drop as the heterostructures are cooled across the normal-superconducting transition and then, depending on the S/F interface morphology, either stays constant or shows a strong upturn. This unique behavior is explained considering the quasiparticle density of states at the YBCO surface and is a direct consequence of zero-gap nodes for particular directions in the momentum space. Besides showing the fingerprint of d-wave superconductivity in spin pumping, our results demonstrate the potential of high-temperature superconductors for fine-tuning the magnetization dynamics in ferromagnets using k-space degrees of freedom of d-wave/F interfaces.
This work, supported by ERC “SUSPINTRONICS”, ANR “SUPERTRONICS” and MSCA “SUPERMAGNONICS” has been published as
“Spin pumping in d -wave superconductor-ferromagnet hybrids” S. J. Carreira, D. Sanchez-Manzano, M.-W. Yoo, K. Seurre, V. Rouco, A. Sander, J. Santamaría, A. Anane, and J. E. Villegas, Phys. Rev. B 104, 144428 (2021)
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Javier E. Villegas 