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| Soliton laser |
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Thin-film medium with sublayer
| Details |
Inventors: Lal, Brij B.; Bourez, Allen J.; Shinohara, Tadashi;
Assignee: HMT Technology Corporation (Fremont, CA)
Primary Examiner: Kiliman; Leszek
Assistant Examiner:
Attorney, Agent or Firm: Mohr; Judy M., Dehlinger; Peter J.
A longitudinal magnetic recording medium formed on a non-metallic substrate and a method of forming the medium is disclosed. A sublayer formed of a chromium alloy having a thickness between 3-50 .ANG. is deposited on the substrate, followed by a chromium-based underlayer. A cobalt-based magnetic recording layer is sputtered over the underlayer. The medium is characterized by improved coercivity, HF signal amplitude and signal-to-noise ratio. |
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DETAILED DESCRIPTION It is, therefore, an object of the present invention to provide a magnetic recording medium formed on a nonmetallic substrate.
It is also an object of the invention to provide a method for producing a magnetic recording medium on a nonmetallic substrate.
The invention includes, in one aspect, a magnetic recording medium, having (i) a non-metallic substrate; (ii) a sputtered sublayer composed of a chromium-based alloy; (iii) a sputtered chromium-based underlayer having a thickness between 200-3,000 .
ANG.
; (iv) a sputtered cobalt-based magnetic layer having a thickness between 100-800 .
ANG.
; and (v) a wear-resistant overcoat.
The sublayer has a thickness between 3-50 .
ANG.
and is composed of a chromium-based alloy, such as Cr--Si, Cr--V, or Cr--Gd.
In one embodiment, the sublayer is formed of Cr--Gd and has a thickness between 10-30 .
ANG.
.
In another embodiment, the sublayer is formed of Cr--V and has a thickness between 10-30 .
ANG.
.
Media formed according to this aspect of the invention are characterized by a substantially higher signal-to-noise ratio than the same medium having a sublayer formed of chromium alone.
The magnetic recording layer of the medium, in another embodiment, is composed of first and second magnetic sublayers separated by a chromium isolation layer.
In another aspect, the invention includes an improvement in a method of producing a magnetic recording medium by (a) sputtering onto a non-metallic substrate a chromium-based underlayer having a thickness of between 200-3,000 .
ANG.
, and (b) sputtering a cobalt-based alloy onto the underlayer to form a magnetic thin-film layer having a thickness between 100-800 .
ANG.
.
The improvement, which is effective to enhance the HF signal amplitude by at least 10%, includes (i) sputtering a sublayer onto the non-metallic substrate, between the underlayer and the substrate; and (ii) prior to sputtering the underlayer, stopping the sublayer sputtering when a sublayer thickness of between 3-50 .
ANG.
is reached.
In accordance with the method, the sublayer may be composed of chromium, or in an alternative embodiment, the sublayer is composed of an alloy such as Cr--Gd, Cr--V, or Cr--Si
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