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Inductive Magnetic Head With Superconducting Flux-Shaping Films

IP.com Disclosure Number: IPCOM000100485D
Original Publication Date: 1990-Apr-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 4 page(s) / 134K

Publishing Venue

IBM

Related People

Cheng, DC: AUTHOR [+2]

Abstract

This article describes new types of inductive heads that take advantage of suitably located superconducting films in the vicinity of the "throat" region of the inductive head to enhance the write field and to reduce or eliminate the pole-gap field that dominates in a normal inductive head. The superconducting films are very effective in "reshaping" the magnetic field patterns near the gap of the pole pieces because of the "field expulsion" or Meissner effect; this can drastically improve the field pattern such that throat height variations become very tolerable (thus precision lapping control is no longer needed), the write field magnitude is increased (thus sensitivity is enhanced), and the fringing field spatial distribution is reduced (thus resolution is enhanced, and the extent of side-writing is reduced).

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Inductive Magnetic Head With Superconducting Flux-Shaping Films

       This article describes new types of inductive heads that
take advantage of suitably located superconducting films in the
vicinity of the "throat" region of the inductive head to enhance the
write field and to reduce or eliminate the pole-gap field that
dominates in a normal inductive head. The superconducting films are
very effective in "reshaping" the magnetic field patterns near the
gap of the pole pieces because of the "field expulsion" or Meissner
effect; this can drastically improve the field pattern such that
throat height variations become very tolerable (thus precision
lapping control is no longer needed), the write field magnitude is
increased (thus sensitivity is enhanced), and the fringing field
spatial distribution is reduced (thus resolution is enhanced, and the
extent of side-writing is reduced).  Furthermore, manufacturability
is improved, compared to regular inductive heads because many
geometrical parameters, including throat height, apex angle, pole tip
thickness and gap width, which must be critically in the manufacture
of the heads, are less critical; this results in a more tolerant and
efficient manufacture process for these new type of heads.  These
advantages are especially valuable, now that high-Tc superconductors
(near 100K) are developed, and shown to be capable of thin-film
deposition, and even higher Tc superconductors are expected to be
forthcoming.

      One example of the superconducting field-controlled inductive
head with three superconducting films S1, S2, and S3 is shown in Fig.
1.  Film S2 in the gap serves the purposes of eliminating the gap
field, and forcing the field to loop outside the tip of S2 at the
Air-Bearing- Surface (ABS).  Films S1 and S3 outside and near the gap
serve the purpose of restricting the spatial extent of the desired
write (i.e., fringing) field outside the ABS.  Note that the field
pattern at the ABS is essentially defined by the spacing gaps among
the films S1, S2, and S3 at the ABS, and not on length of the
narrow-gap region of the pole tips (so-called throat heights) nor on
any recession of the pole tips from the ABS.

      The extension of the idea of field-shaping and field-definition
by superconducting films into two-dimensional considerations is
schematically shown in Fig. 2.  Here, we indicate that
superconducting "Walls" S4 and S5 can be used to restrict the lateral
write field spread, and hence, reduce side-writing.

      With the use of superconducting field-shaping films, indicated
in Figs. 1 and 2...