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Laminated Films with Alternately Skewed Easy Axis for Magnetic Transducers

IP.com Disclosure Number: IPCOM000087452D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Thompson, DA: AUTHOR [+2]

Abstract

When magnetic transducers are miniaturized so that the size of their magnetic structures is comparable to the domain size, performance is adversely affected by the presence of domain walls. There is either Barkhausen noise or nonrepeatability of the output pulse, the latter being but a low-frequency Barkhausen noise.

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Laminated Films with Alternately Skewed Easy Axis for Magnetic Transducers

When magnetic transducers are miniaturized so that the size of their magnetic structures is comparable to the domain size, performance is adversely affected by the presence of domain walls. There is either Barkhausen noise or nonrepeatability of the output pulse, the latter being but a low-frequency Barkhausen noise.

One way of eliminating high- and low-frequency Barkhausen noise is prevention of domain-wall formation. Lamination of films forming the magnetic yoke of a transducer prevents formation of closure domains, but domain walls parallel to the easy axis of magnetization remain. One can eliminate the latter domain walls also by using unidirectional bias. The laminae are biased either alternately in opposite directions or every other lamina is biased in the same direction. Unidirectional bias may be achieved by way of exchange anisotropy, which requires lamination with aa suitable antiferromagnetic material.

A simple way of biasing successive laminae in opposite directions is by alternate skewing of the easy axis, as shown in the figure. The figure is a view looking down on the plane of the film. All of the vectors shown, including the applied field, are in the plane of the film.

The figure shows the magnetization M in a laminated film with alternately skewed easy axis after application and removal of a field. The skew angle beta is typically between 10 degrees and 20 degrees. After a...