Extraction of the response function of GMR head for spin-stand imaging

Abstract

In this paper, an advanced extraction technique of the response function of giant-magnetoresistive (GMR) head for use in spin-stand imaging is presented. The essence of this technique is the spatial averaging of readback signals of many identically written "point-like" charges resulted from dc-trimmed transitions. As a result of the averaging, the noise generated by random fluctuations of medium properties is filtered out. This extraction technique also restores the symmetry of the head response function by employing a nonstandard dc-trimming procedure and a modified bias condition for the read process. By using the extracted head response function, we were able to reconstruct magnetization images of overwritten data with a misregistration of 50 nm.

Scaling of head response function in spin-stand imaging

“…5. In our experiments, all measurements were performed by using a Guzik 1701 MP spin-stand and readback voltages were acquired with a oscilloscope.…”

“…[1][2][3][4][5][6] In this technique, images are acquired by scanning a target area of the hard disk by a giant magnetoresistive ͑GMR͒ head in the along-and cross-track directions. [1][2][3][4][5][6] In this technique, images are acquired by scanning a target area of the hard disk by a giant magnetoresistive ͑GMR͒ head in the along-and cross-track directions.…”

“…[1][2][3][4][5] This scaling procedure is very important and is at the heart of the image reconstruction technique. The discussion of the scaling technique and the demonstration of its effectiveness is the novel contribution of this paper that clearly distinguishes it from previous publications.…”