Off-Track Performance of NiFe/CoNiFe Laminated Thin-Film Heads

The read-write performances and off-track performances of thin-film heads with NiFe/CoNiFe/NiFe laminated upper poles are studied in comparison with those of a coventional NiFe head and NiFe/CoNiFe laminated heads. NiFe/CoNiFe/NiFe laminated heads with 0.3 μm gaplength have a good overwrite performance equal to that of NiFe/CoNiFe laminated heads with 0.4 μm gap-length. However, the amplitude and PW50 of the isolated pulse are equal to the values for an NiFe head and NiFe/CoNiFe laminated heads with 0.3 μm gap-length Therefore, the effective gap-length becomes wider in a write process, owing to the prevention of magnetic saturation of the inner NiFe film. The effective write-track width of NiFe/CoNiFe/NiFe laminated heads is the same as that of NiFe/CoNiFe laminated heads, because of prevention of head pole tip saturation. Therefore, NiFe/CoNiFe/NiFe laminated heads are suitable for magnetic recording with higher BPI and TPI.