Measurement of head magnetization in the presence of pseudo-backlayer by using focused hard X-ray magnetic circular dichroism

摘要

Recording performances in perpendicular magnetic recording are strongly governed by the main pole dynamics of single-pole-type (SPT) write heads. For instance, saturation magnetization, B_s, of the main pole is closely related to the upper limit of the head's field strength. Furthermore, remanent magnetization of the main pole tip causes undesired erasure of the recorded signals after the write operation. The soft magnetic backlayer of the medium behaves as a part of the head so as to smooth the return flux flow path. Therefore, investigating the dynamic magnetic behavior of the actual main pole in the presence of the soft magnetic backlayer is important for designing a single pole head. Electron beam tomography [1] and Kerr microscopy [2] have been used to observe the main pole dynamics; however, these methods could not be used to estimate the dynamic head magnetization behavior in the presence of the soft magnetic backlayer. To measure the magnetization dynamics, a hard X-ray magnetic circular dichroism (XMCD) analysis [3] with a high resolution focused beam was used since the hard X-ray could penetrate through the pseudo soft magnetic backlayer. We successfully measured the magnetization of the main pole on which a soft magnetic film was formed as a pseudo soft magnetic backlayer. This paper reports preliminary experiments on the static and dynamic measurements of the head's main pole magnetization.