Spin-wave modes in permalloy/platinum wires and tuning of the mode damping by spin Hall current

We report measurements of spectral properties of spin-wave modes in permalloy/platinum (Py/Pt) bilayer wires magnetized along two principal in-plane axes. We find that the spin torque arising from the spin Hall current in Pt can significantly reduce the spectral linewidth of the bulk and edge spin-wave modes of the wire magnetized perpendicular to its long axis. The linewidth reduction is strongest for the quasiuniform mode and weakest for the edge mode. Our work demonstrates the importance of extrinsic contributions to spin-wave damping for tuning of magnetization dynamics by spin Hall current.