Digital magnetic recording theory

Abstract

A brief review of digital magnetic recording theory is given with emphasis on the analysis of ferrite, inductive thin film, and magnetoresistive heads. The utility of several approaches is demonstrated by three calculations: (1) resolution and signal amplitude of a shielded magnetoresistive head, (2) readback properties of a single sheet of permalloy with adjacent current conductor, and (3) analysis of spurious pulses generated by outside corners of ferrite heads. A discussion of high density digital recording is given, and it is concluded that the magnetoresistive head offers the greatest possible areal density of information. This density is conservatively estimated to be 1.6×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> flux reversals per cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> per in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) at a head-medium separation of 0.125μm. Experimental data in support of this conclusion are given.