Comparison of perpendicular and longitudinal magnetic recording using a contact write/read tester

We have performed longitudinal and perpendicular magnetic recording measurements using a contact write/read tester, which scans a magnetic recording head in contact with the recording media. Our tester has a demonstrated positioning resolution of <5 nm. Perpendicular transitions in the range 125-425 kfci were recorded on double-layer perpendicular media with a high moment soft underlayer. The perpendicular bits were imaged using both a giant magnetoresistance (GMR) read head on the contact tester and using magnetic force microscopy (MFM). Longitudinal bit transitions with linear densities in the range 25 to 725 kfci were recorded, and the signal-to-noise ratios of both the perpendicular and longitudinal systems were measured.