Investigation of the Exchange Bias Effect by Quantitative Magnetic Force Microscopy

Magnetic force microscopy (MFM) measurements were performed on an exchange‐biased CoO/(Co/Pt) multilayer sample at 8.0 K. Applying an external magnetic field of up to 7.0 T saturates the ferromagnetic layer and the remaining uncompensated antiferromagnetic spins at the antiferromagnet/ferromagnet interfaces are imaged with high lateral resolution. The coupling between the uncompensated spins and the spins in the ferromagnet are found to be antiferromagnetic. In addition, a method to quantitatively analyze the MFM data is presented which allows the determination of the uncompensated spin density at the AF/FM interfaces. It was found that 7% of the spins at the interfaces are uncompensated and contribute to the exchange biasing.