Detection of localized ferromagnetic resonance in a continuous thin film via magnetic resonance force microscopy

We present magnetic resonance force microscopy (MRFM) measurements of ferromagnetic resonance in a 50 nm thick permalloy film tilted with respect to the direction of the external magnetic field. At small probe-sample distances the MRFM spectrum breaks up into multiple modes, which we identify as local ferromagnetic resonances confined by the magnetic field of the MRFM tip. Micromagnetic simulations support this identification of the modes and show they are stabilized in the region where the dipolar tip field has a component antiparallel to the applied field.