Magnetization in a spin valve head mapped by an MFM tip

We have mapped the magnetization distribution in a spin valve head by monitoring its magneto-resistance δR, while scanning the sample surface with an MFM tip. We find that conventional tips give enhanced response at two edges of the sensor. In comparison, mapping with horizontally magnetized tips shows no such artifacts. This is because conventional tips produce in-plane magnetic field components in all radial directions, thus the response δR does not simply correspond to local magnetization. In contrast, horizontally magnetized tips produce fields along a single direction. Therefore, mapping of δR renders the approximately single-domain magnetization in our spin valve films