Micro-Magnetic Study And Design Of Magnetic Data Storage System With Ultra-High Density

As the main supporter of the information storage, magnetic recording technology and magnetic disk drives with low cost, high reliability and fast increased density, always push forward the progess of information industry. When the recording density gradually approaches to1Tb/in2, how to break the density limit of conventional perpendicular magnetic recording with new technologies, and push the density of magnetic disk drive from0.15-0.2Tb/in2in the begin year (2008) of this study to10Tb/in2-60times increase-in future15-20years is the research with widespread concern. In this dissertation, the feasibility of achieving multi-Tb/in2magnetic data storage using patterned media recording and shingled writing technology is explored through micromagnetic modeling. And the10Tb/in2shingled writing based patterned media recording system is designed in detail from both the magnetic head and magnetic recording media aspects. The head design includes the writing head structure, writing corner angle, corner rounding effect, skew angle and the high-frequency responsibility, and the media design includes the recording media structure, magnetic properties and bit cell arrangement. This design provides a practicable progress scheme of key technologies in magnetic data storage.This research independently models the shingled writing head for10Tb/in2magnetic recording, and studies the effects of the head structure on the writing field and field gradient using micro-magnetic calculation. All the effects are also illustrated from magnetism theory. Based on the simulation results, this paper originally reveals that the writing field and field gradient around the writing corner of shingled writing head are more important for achieving10Tb/in2magnetic recording, compared with the maximum writing field, and the increasing trend of writing field will rapidly slow down as the pole tip width increases. Other head structures, such as pole tip tapered angle, shield gap length and pole tip height, need to be set at reasonable levels to achieve10Tb/in2shingled magnetic recording.This work derives the recording performance calculation method of shingled writing based patterned media recording system. The effects of writing head with different writing comer on the recording performance are calculated and compared, and the optimal writing comer angle is suggested from the consideration of decreasing the write-in error rate. Furthermore, the "corner rounding effect" of shingled writing head is also studied. The influence of different rounded writing comers upon the recording performance is calculated through micro-magnetic modeling, and the results show that the writing head with small rounded corner is benefit for the write-in error rate decrease of10Tb/in2shingled magnetic recording system.The maximum erasing error rate of10Tb/in2shingled magnetic recording system with different skew angle range is studied through micro-magnetic calculation. The results show that reducing the skew angle range is benefit for improving the writing performance when recording density increases. Therefore, this work proposes the dual-corner shingled writing technology for reducing skew angle range. Using this writing method, the skew angle range of each writing comer can be reduced into10°and the recording performance of shingled recording system can be fundamentally increased.The reversal requirements of patterned bit cell are calculated under the practical writing field distribution. The high-frequency response characters of10Tb/in2shingled writing head are also studied. The simulation results reveal that increasing the damping constant of recording media is an effective way to enchance the high-frequency response performance of10Tb/in2shingled magnetic recording system. The shingled writing head is also designed in detail to satisfy the high-frequency response requirements.The magneto-static interference of surrounding patterned bit cells in different bit cell arrangements and manufacturing induced deviations is studied. Commonly used bit cell arrangements are categorized into three representative types:square arrangement, isosceles triangular arrangement and equilateral triangular arrangement. Compared with other two arrangements, the equilateral case introduces strongest cell-to-cell interference and shows the greatest sensitivity to manufacturing induced deviations. The isosceles triangular arrangement is a recommended approach in terms of reducing the possible switch field distribution broadening, caused by manufacturing induced bit cell position offset and bit cell size variation, without introducing extra track positioning accuracy requirement.