Interfaces between materials with differently ordered phases present unique opportunities for exotic physical properties, especially the interplay between ferromagnetism and superconductivity in the ferromagnet/superconductor heterostructures. The investigation of zero- and pi-junctions has been of particular interest for both fundamental physical science and emerging technologies. Here, we report the experimental observation of giant oscillatory Gilbert damping in the superconducting Nb/NiFe/Nb junctions with respect to the NiFe thickness. This observation suggests an unconventional spin pumping and relaxation via zero-energy Andreev bound states that exist only in the Nb/NiFe/Nb pi-junctions, but not in the Nb/NiFe/Nb zero-junctions. Our findings could be important for further exploring the exotic physical properties of ferromagnet/superconductor heterostructures, and potential applications of ferromagnet pi-junctions in quantum computing, such as half-quantum flux qubits.
@article{arxiv.2111.03233,
title = {Giant oscillatory Gilbert damping in superconductor/ferromagnet/superconductor junctions},
author = {Yunyan Yao and Ranran Cai and Tao Yu and Yang Ma and Wenyu Xing and Yuan Ji and Xin-Cheng Xie and See-Hun Yang and Wei Han},
journal= {arXiv preprint arXiv:2111.03233},
year = {2021}
}