Write Characteristics of Simple Structured Single Pole Head

Abstract

Abstract----The write head design for a merged MR head needs to be optimized to obtain a good wrIte performance for a perpendicular magnetic recording application. We fabricated a write-only single pole head with the simplified structure which consists of a main pole and a thin film coil without a return yoke. The write performance of the single pole head with double-layered media was evaluated by using an MR read head. The O/W value obtained was less than -35dB, and the PWso value obtained from the differentiated curve of the readback waveform was 0.20 J1 m. The small PWsofrom the recorded bits attributes to the sharp magnetic transitions.Key words: perpendicular magnetic recording, single pole head, simplified structure, write head, MR head, I . INTRODUCTIONPerpendicular magnetic recording is expected to be an important technology for high recording density. The areal density of lOGbitslin 2 and beyond was obtained experimentally, using a sjngle-pole head and a double-layered perpendicular medium [1]. The combination of an MR head and a double-layered medium is also a promising technology for future high-density recording [2]. Muraoka et.at. pointed out the 50% linear density(D50) of the roll-off curve measured by the MR head increased by 70% associating with the differential equalizer [3].If an MR head is used as a read element, a write head becomes simplified structure which consists of a main pole and a thin film coil, without a return yoke. It is because the recording process of a perpendicular magnetic recording single pole head on a double-layered medium is carried out through a main pole, a recording layer and an under-layer of the medium.It is considered that write head design should be optimized to obtain a good write performance of the merged MR head for perpendicular magnetic recording. In this study, we developed a simple structured write-only single pole head without the return yoke on the basis of analytical results from a computer simulation. The structure and write characteristics of the write-only single pole head when read out by the MR head are discussed. IT . EXPERIMENTALThe write magnetic field amplitude ofthe simplified singlepole head without a return yoke(Head A) was calculated using a three-dimensional finite element method, and that of the conventional single pole head(Head B) [4] was also calculated for comparison.The head was fabricated by a thin film process with the help of an analytical simulation. Electrical performances of the head were measured by a GUZIK read/write analyzer (RWA1601), and an MRhead was used as a read head at the flying height of 40nm.In order to investigate the write performance of Head A, we measured saturation characteristics for this head, and also measured for Head B as a reference. The roll-off curves and isolated waveforms when read by the MR head were measured for the following three cases concerning media and write heads. Case A; a longitudinal medium and a ring head, Case B; a perpendicular medium and a ring head, and Case C; a perpendicular medium a...