Neighborhood induced reader bias shift in perpendicular recording

A spin-stand technique to determine the influence of the neighborhood on readback in perpendicular recording is presented. A square wave was recorded on an ac erased medium. Stray fields from neighboring tracks resulted in reader bias shift and thereby second-harmonic distortion in the spectrum of the square wave. An external perpendicular field applied to compensate the distortion provided a measure of the neighborhood effect on readback. A dc magnetized track written approximately a track width away was found to change the required compensating field by 5 Oe. Additional dc tracks further enhanced or diminished the compensating field depending on their relative magnetization direction. The immediate neighborhood was proven to have a dominating influence on the reader bias. (C) 2003 American Institute of Physics.