Strain imaging of a ferrite core head

This paper describes magnetic domain observation of a ferrite core head of a hard-disk drive (HDD) using a new method. The principle of the method, strain imaging, is detection and imaging of the strains generated in a magnetic material subjected to an external magnetic field, using a scanning probe microscope (SPM). Because the magnetic-field induced strains involve the factors depending on the magnetization of each domain, we can image domain structures by detecting the surface displacements induced by the strains, using the SPMs. The atomic resolution of the SPMs results in strain imaging with high resolution. We observed that domains aligned to the magnetic field increased with the coil current of the ferrite core head. Nothing, except for magnetic fields provided by the head coil itself, has any magnetic influence on the domain structures of the ferrite core. Thus, this method is suitable for domain observation of HDD heads made of soft materials.