Abstract
Spin pumping across ferromagnet/superconductor (F/S) interfaces has attracted much attention lately, yet the focus has been mainly on -wave superconductor based systems whereas (high-temperature) -wave superconductors such as (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 (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 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 -wave superconductivity in spin pumping, our results demonstrate the potential of high-temperature superconductors for fine tuning of the magnetization dynamics in ferromagnets using -space degrees of freedom of -wave/F interfaces.
- Received 8 September 2020
- Revised 21 September 2021
- Accepted 11 October 2021
DOI:https://doi.org/10.1103/PhysRevB.104.144428
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