  Using measurements of the spectra of microwave-frequency resistance
oscillations, we determine the phase diagram of magnetic excitations caused by
torques from DC spin-polarized currents in (thin permalloy)/copper/(thick
permalloy) multilayer samples. We extend the measurements to larger values of
current than have been reported previously. We find several additional modes
that we are able to identify with motion of the thick magnetic layer as well as
the thin one. Peaks in the microwave spectra at multiple frequencies suggest
that spatially non-uniform dynamical states can be important in some
circumstances. We compare the experimental phase diagram with simple
theoretical models and achieve a good qualitative agreement.
