Two-Dimensional Coding for Probe Recording on Magnetic Patterned Media

The effect of intertrack intersymbol interference in a magnetic patterned medium is studied. A 2-D channel code is proposed, dedicated to perpendicularly magnetized media without soft underlayer, which exhibit read pulses showing overshoot. Read pulse shapes were investigated using a magnetic-force microscope tip scanning the patterned medium row by row. To test different codes, a bit-detection simulation program was developed to generate large amounts of data on which bit error rates can be measured. Application of the 2-D channel code, which implies recording of particular dot positions with fixed bits ("ones," "zeros") resulted in the elimination of 2-D worst case bit patterns and a subsequent reduction of detected-bit errors. The accompanying redundancy of 22% is inevitable for this type of 2-D code