With areal density constantly increasing at a rate of 60% annually, it is becoming increasingly more difficult to maintain the precise positioning required of the ever-smaller GMR heads to read and write data. Roadmaps are now calling for areal density to reach 50 Gbits/in~2 by the year 2003 with a corresponding track density of 70,000 tracks per inch (tpi). At a track density of 50,000 tpi, the track pitch is 508 nm; at this track density, the head must be positioned with an accuracy of less than 50 nm in order to read data with sufficiently low inter-track crosstalk.
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