Possible Evidence for Spin-Transfer Torque Induced by Spin-Triplet Supercurrents
Lai-Lai Li1,3, Yue-Lei Zhao2**, Xi-Xiang Zhang2, Young Sun1,3**
1Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 2King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia 3School of Physical Science, University of Chinese Academy of Sciences, Beijing 100190
Abstract：The mutual interplay between superconductivity and magnetism in superconductor/ferromagnet heterostructures may give rise to unusual proximity effects beyond current knowledge. Especially, spin-triplet Cooper pairs could be created at carefully engineered superconductor/ferromagnet interfaces. Here we report a giant proximity effect on spin dynamics in superconductor/ferromagnet/superconductor Josephson junctions. Below the superconducting transition temperature $T_{\rm C}$, the ferromagnetic resonance field at X-band ($\sim$9.0 GHz) shifts rapidly to a lower field with decreasing temperature. In strong contrast, this phenomenon is absent in ferromagnet/superconductor bilayers and superconductor/insulator/ferromagnet/superconductor multilayers. Such an intriguing phenomenon can not be interpreted by the conventional Meissner effect. Instead, we propose that the strong influence on spin dynamics could be due to spin-transfer torque associated with spin-triplet supercurrents in ferromagnetic Josephson junctions with precessing magnetization.
2018, Vol. 35 
