Magnetic force microscopy (MFM) is well suited to exploring ferromagnetic domain structures.  Moreover, the dynamic magnetism cannot be characterized because MFM is only sensitive to the static magnetic fields.  Here, we develop a side-band magnetic force microscopy (MFM) to locally observe the alternating magnetic fields in nanometer length scales at an operating distance of 1 nm.  Variations in alternating magnetic fields and their relating time-variable magnetic domain reversals have been demonstrated by the side-band MFM.  Based on the side-band MFM, the magnetic moment can be determined locally in a volume as small as 5 nanometers. 
MFM
Variations in alternating magnetic fields and their relating time-variable magnetic domain reversals have been demonstrated by the side-band MFM.  Based on the side-band MFM, the magnetic moment can be determined locally in a volume as small as 5 nanometers. 
side-band MFM