  We utilized microwave spectroscopy to study the magnetization oscillations
locally induced in a Permalloy film by a pure spin current, which is generated
due to the spin Hall effect in an adjacent Pt layer. The oscillation frequency
is lower than the ferromagnetic resonance of Permalloy, indicating that the
oscillation forms a self-localized nonpropagating spin-wave soliton. At
cryogenic temperatures, the spectral characteristics are remarkably similar to
the traditional spin-torque nano-oscillators driven by spin-polarized currents.
However, the linewidth of the oscillation increases exponentially with
temperature and an additional peak appears in the spectrum below the
ferromagnetic resonance, suggesting that the spectral characteristics are
determined by interplay between two localized dynamical states.
