Data Storage Systems Center

This overview summarizes the work in servo, mechanics, and tribology. The servo work spans design of microactuators for skew compensation, position signal generation on patterned media, and connects to tribology through investigations of friction in actuator pivot bearings. Tribology work includes molecular dynamics simulations of lubricant behavior on disks and characterization of real surfaces for prediction of asperity contacts between slider and disk. Molecular dynamics simulations are also the focus of work on understanding the development of microstructure in thin film media and on the mechanisms and structure of Ge2Sb2Te5 as a phase change material.

For discrete track media to become a viable alternative, it is essential to produce accurate servo patterns in a cost effective manner [1]. This study presents a comparative analysis of position error signals generated from spin stand readback waveforms on various lithographically defined servo patterns and servo bursts written on continuous regions of the same perpendicular magnetic recording (PMR) media. Positive and negative AB burst amplitude patterns, short length AB bursts, and chevron phase patterns were patterned using an electron beam lithography fabrication process on conventional PMR media [2]. The continuous media bursts were written on the same disk in areas away from the patterned regions by first writing a burst and then AC trimming the sides of the burst at a 100nm offset. The results demonstrate that edge variation on the patterned servo elements is a factor of two less than that found on conventional servo bursts. In addition, evidence shows that despite some amplitude loss resulting from the removal of magnetic material, patterned servo bursts produce good quality position error signals when compared to servo bursts written on continuous media.

[1] X. Che, K.-S. Moon, Y. Tang, N.-Y. Kim, S.-Y. Hong, H. J. Lee, M. Moneck, J.-G. Zhu, and N.        Takahashi, IEEE Trans. Magn., 2007 (to be published) 
[2] M. T. Moneck, J.-G. Zhu, X. Che, Y. Tang, H. J. Lee, S. Zhang, K.-S. Moon, and N. Takahashi, IEEE Trans. Magn., 43, 2127 (2007)