A study of high-frequency characteristics of write heads with the ac-phase high-frequency magnetic force microscope

We demonstrate frequency characteristic measurement methods of write head with an ac-phase high-frequency magnetic force microscope (HF-MFM). Two measurement methods allow separating the characteristics into electrical ones including the head amplifier and/or interconnects and magnetic ones including head materials. The high spatial resolution ac-phase HF-MFM allows resolving the distribution change of the HF magnetic field with frequency. The relation between HF-MFM and spin-stand data was also investigated. It is thought that HF-MFM measurements can be applied to head performance test before HDD manufacturing.