Micromagnetic study of a spin-torque oscillator based on a magnetic   nano-contact magnetized at an arbitrary angle
  The nature of spin wave modes excited by spin-polarized direct current in a spin-torque auto-oscillator based on a magnetic nanocontact was studied by a micromagnetic simulation in the case when the external bias magnetic field was rotated from the in-plane to perpendicular-to-plane orientation. In qualitative agreement with the weakly-nonlinear analytical theory it was found, that at a certain critical angle, an abrupt switching from the self-localized nonlinear "bullet" mode to a propagating quasi-linear Slonczewski mode takes place, and is accompanied by an upward jump in generated microwave frequency. It was, also, found that the analytical theory overestimates the magnitude of a critical magnetization angle, corresponding to the mode switching, and that the magnitude of the frequency jump caused by the mode switching is inversely proportional to the nanocontact radius. 
G. Consolo, B. Azzerboni, L. Lopez-Diaz, G. Gerhart, E. Bankowski, V.   Tiberkevich, A.N. Slavin