Magnetic resonance force spectroscopy of magnetic vortex oscillations

Forced oscillations of magnetization of NiFe circular disk in the presence of external longitudinal magnetic field are studied with the aid of micromagnetic simulation and experiments using magnetic resonance force spectroscopy. Main attention is paid to low-frequency resonance related to gyrotropic motion of the core of magnetic vortex. The resonance frequency of the gyromode is significantly shifted when the external magnetic field is applied in the sample plane. Effect of nonuniform magnetic field of the probe on the oscillations of magnetization is discussed.