Perpendicular magnetic recording system and medium with high-moment corrosion-resistant “soft” underlayer (SUL)
First Claim
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1. A perpendicular magnetic recording medium comprising:
- a substrate;
a perpendicular magnetic recording layer; and
an underlayer comprising magnetically permeable material between the substrate and the recording layer, the magnetically permeable material being an alloy consisting essentially only of Co, Fe, Ta and Zr wherein the combined amount of Ta and Zr in said CoFeTaZr alloy is greater than or equal to 10 atomic percent and less than or equal to 20 atomic percent and the moment (Ms) is greater than or equal to 11 kOe, and wherein said CoFeTaZr alloy exhibits a corrosion current at zero electrical potential in an electrochemical corrosion test and a Co92Ta3Zr5alloy exhibits a corrosion current at zero electrical potential in said test that is at least 15 times the corrosion current of said CoFeTaZr alloy.
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Abstract
A perpendicular magnetic recording disk has a soft magnetic underlayer (SUL) that has high corrosion resistance as well as high moment. The material of the SUL is an alloy comprising Co, Fe, X, and Y; where X is Ta or Nb, Y is Zr or Hf, and the combined amount of X and Y present in the alloy is between about 10 and 20 atomic percent. The atomic ratio of Co to Fe in the alloy is between about 90:10 to 10:90, preferably between about 25:75 and 35:65. The SUL may be a single-layer SUL or a multilayer SUL formed of multiple soft magnetic layers separated by an interlayer film or films.
22 Citations
17 Claims
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1. A perpendicular magnetic recording medium comprising:
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a substrate; a perpendicular magnetic recording layer; and an underlayer comprising magnetically permeable material between the substrate and the recording layer, the magnetically permeable material being an alloy consisting essentially only of Co, Fe, Ta and Zr wherein the combined amount of Ta and Zr in said CoFeTaZr alloy is greater than or equal to 10 atomic percent and less than or equal to 20 atomic percent and the moment (Ms) is greater than or equal to 11 kOe, and wherein said CoFeTaZr alloy exhibits a corrosion current at zero electrical potential in an electrochemical corrosion test and a Co92Ta3Zr5alloy exhibits a corrosion current at zero electrical potential in said test that is at least 15 times the corrosion current of said CoFeTaZr alloy. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A perpendicular magnetic recording disk comprising:
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a substrate; a magnetically permeable underlayer on the substrate and comprising an alloy consisting essentially only of Co, Fe, Ta and Zr, wherein the combined amount of Ta and Zr in said CoFeTaZr alloy is greater than or equal to 10 atomic percent and less than or equal to 20 atomic percent and the moment (MS) is greater than or equal to 11 kOe, and wherein said CoFeTaZr alloy exhibits a corrosion current at zero electrical potential in an electrochemical corrosion test and a Co92Ta3Zr5alloy exhibits a corrosion current at zero electrical potential in said test that is at least 15 times the corrosion current of said CoFeTaZr alloy; a perpendicular magnetic recording layer comprising grains of a Co-based ferromagnetic alloy having a hexagonal-close-packed (hcp) crystalline structure with the c-axis oriented substantially perpendicular to the recording layer; and an exchange-break layer between the underlayer and the recording layer for magnetically decoupling the recording layer and the underlayer. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification