  We experimentally study spin-Hall nano-oscillators based on [Co/Ni]
multilayers with perpendicular magnetic anisotropy. We show that these devices
are capable of single-frequency auto-oscillations at current densities
comparable to those in the in-plane magnetized oscillators. The demonstrated
oscillators exhibit large magnetization precession amplitudes, and their
oscillation frequency is highly tunable by the electric current. These features
make them promising for applications in high-speed integrated microwave
circuits.
