Current-induced magnon trapping in spin torque oscillation

Spin torque nano-oscillators realized by magnetization dynamics trapped in a current-induced potential are reported. We fabricated Ni$_{81}$Fe$_{19}$/Pt nanostructures and measured current-induced microwave emission from the structures. The result shows an increase in the magnitude and spectral narrowing of the microwave emission. We demonstrate that the current-induced magnetic field suppresses magnon radiation loss and significantly reduces the linewidth and the threshold current required for the spin torque oscillation.