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

Summary form only given Previously (Mayergoyz et al. J. Appl. Phys. vol.87, p.6824, (2000)), the spin-stand imaging technique was proposed for the retrieval of overwritten or partially erased magnetization patterns on hard disks. This technique is based on the response function characterization of GMR heads. This characterization is performed by writing a transition which is then trimmed by dc-erasure. As a result, a tiny isolated spot of magnetic charge is created that can be viewed as an approximation to a point charge and can be used to characterize the response function of GMR element. However, this magnetic charge is very small and is buried in "random" magnetic charges that appear due to the fluctuations of magnetic medium properties. Consequently, the magnetic head response is strongly contaminated with noise generated by these random magnetic charges and the problem of extracting the response function of GMR head presents itself.