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Magnetic Medium with Improved CoPtCr Alloy

IP.com Disclosure Number: IPCOM000111895D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Doerner, MF: AUTHOR [+3]

Abstract

Disclosed is an improved CoPtCr alloy composition for longitudinal magnetic recording. Performance is optimum for a Cr concentration of 22-23 at.% with Pt as high as 14 at.%.

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Magnetic Medium with Improved CoPtCr Alloy

      Disclosed is an improved CoPtCr alloy composition for
longitudinal magnetic recording.  Performance is optimum for a Cr
concentration of 22-23 at.% with Pt as high as 14 at.%.

      The optimum Cr concentration in CoPtCr alloys is found to be
near 22 at.%.  The coercivity drops significantly between 22 and 25
at.% Cr although the saturation magnetization (Ms) decreases linearly
in this range.  The coercivity drop is most likely a result of the
decrease in Curie temperature (Tc) from 400C to 160C for an increase
in Cr concentration from 22 to 25 at.%.  The media signal-to-noise
ratio (S/Nm) increases with Cr concentration up to 25 at.% Cr for
thin magnetic layers (0.6 memu/cm2), but peaks at 22 at.% for thicker
films.  The Soft Error Rate (SER) given in Table 1 shows the optimum
performance at 22 at.% Cr.  The Tc measurements indicate that
addition of Pt has very little effect on the reduction of Tc.
Therefore, the Pt concentration range can be extended to 14 at.% with
22 at.% Cr.

Soft Error Rate Results.  105 KBPI Linear Density

                +-----------------------------+-----------+
                | Co-Pt-Cr Composition (at.%) | log (SER) |
                | Co-Pt-Cr Composition (at.%) | log (SER) |
                | Co-Pt-Cr Composition (at.%) | log (SER) |
                | Co-Pt-Cr Composition (at.%) | log (SER) |
       ...