/spl mu/track profiles for investigating side effects of advanced silicon heads for helical scan tape systems

Summary form only given. Track and /spl mu/track scans are common techniques in hard disk systems for investigating side writing and side reading, and for characterizing the response of MR read heads. These methods are implemented less in tape systems, where the contact recording mode and flexible medium make it difficult to obtain a smooth relative movement between head and medium. Positioning instability generates fluctuations in track profiles (S. Fukuda et al, 2000). We optimized an experimental system, using helical scan type heads and tape wound on a rotary drum, for measuring sub-/spl mu/m track profiles. Writing and reading operations are performed with the same helical scan silicon (HSS) head, fabricated with advanced thin film technology. HSS heads feature unique properties such as an integrated solenoid coil (DC resistance <8 /spl Omega/ for 40 turns), and very small pole widths. The very good alignment of the polar pieces is expected to minimize side effects. In this paper, we report /spl mu/track profile measurements for investigation of track edge behavior of HSS heads in combination with MP and ME tapes. Heads with optical pole widths as narrow as 3.3 /spl mu/m and 0.11 /spl mu/m gap length have been studied. Narrower tracks are obtained by recording a first track and partially erasing it from one side by writing a second track at a different wavelength. The positioning accuracy achieved, better than 0.1 /spl mu/m with all precautions, allows use of this method for side erasure measurements. Using a 0.5 /spl mu/m wavelength track to partially overwrite a 0.4 /spl mu/m wavelength we find a side erasure band of 0.3 /spl mu/m (with MP tape, H/sub c/=135 kA/m). Results are compared with MFM observations and qualitative agreement is proved. We also describe novel profiling methods for quantifying side reading, and report experimental results. The difference between the side erasure band (SEB) and the side reading band (SRB) can be determined by writing a - rack in the middle of two adjacent tracks having different wavelengths. All wavelengths are read during the same scan.