Magnetic recording medium and magnetic recording apparatus using the same

• US 6,447,936 B1
• Filed: 06/15/2000
• Issued: 09/10/2002
• Est. Priority Date: 05/29/1997
• Status: Expired due to Fees

• Current Assignee: Hitachi Global Storage Technologies Japan Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Ito, Kenya, Hirayama, Yoshiyuki, Futamoto, Masaaki, Honda, Yukio, Yoshida, Kazuetsu, Inaba, Nobuyuki
• Primary Examiner(s): Thibodeau, Paul
• Assistant Examiner(s): Rickman, Holly C.
• Application Number:
  US09/594,570
• Time in Patent Office: 817 Days
• Field of Search: 428/694.TM, 428/694.MT, 428/694.MM, 428/900, 428/332, 428/213, 428/212, 428/694.TS
• US Class Current: 428/827
• CPC Class Codes: G11B 5/66 the record carriers consisting of several layers
• CPC Class Codes: G11B 5/674 having differing macroscopic or microscopic structures, e.g. differing crystalline lattices, varying atomic structures or differing roughnesses
• CPC Class Codes: H04B 10/504 using direct modulation
• CPC Class Codes: Y10S 428/90 Magnetic feature
• CPC Class Codes: Y10T 428/12465 having magnetic properties, or preformed fiber orientation coordinate with shape
• CPC Class Codes: Y10T 428/12861 Group VIII or IB metal-base component
• CPC Class Codes: Y10T 428/12875 Platinum group metal-base component
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/2495 Thickness [relative or absolute]
• CPC Class Codes: Y10T 428/24975 No layer or component greater than 5 mils thick
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/265 1 mil or less

Abstract

Magnetic recording medium includes at least two layers having different magnetic anisotropy constants formed on a substrate and the perpendicular magnetic anisotropy of the second magnetic film of those magnetic films, far from the substrate surface, made equal to or larger than that of the first magnetic film near to the substrate surface, thus improving the magnetic isolation of the first magnetic film near to the substrate surface.

Claims

1. A perpendicular recording medium, comprising:

a substrate;

an underlayer formed on said substrate;

a first perpendicular magnetization film having a first magnetic anisotropy energy formed on said underlayer; and

a first amorphous perpendicular magnetization film having a second magnetic anisotropy energy, formed on said first perpendicular magnetization film,

wherein, the second magnetic anisotropy energy of said first amorphous perpendicular magnetization film is greater than the first magnetic anisotropy energy of said first perpendicular magnetization film, and

further wherein, a thickness of the first amorphous perpendicular film is less than a thickness of the first perpendicular magnetization film, and

a total thickness of said perpendicular magnetization film and the first amorphous perpendicular film is within a range of 7 nm to 100 nm.

2. The perpendicular recording medium according to claim 1 further comprising:

a second amorphous perpendicular magnetization film having a third magnetic anisotropy energy formed under said first perpendicular magnetization film,

wherein a thickness of the second amorphous perpendicular film is less than a thickness of the first perpendicular magnetization film, and

a total thickness of said first perpendicular magnetization film, the first amorphous perpendicular film and the second amorphous perpendicular film is within a range of 7 nm to 111 nm.

3. A perpendicular recording medium comprising:

a first perpendicular magnetization film having a first magnetic anisotropy energy,

a first amorphous perpendicular magnetization film having a second magnetic anisotropy energy formed on an upper side of said first perpendicular magnetization film,

a second amorphous perpendicular magnetization film having a third magnetic anisotropy energy formed on a lower side of said first perpendicular magnetization film wherein,

the second magnetic anisotropy energy of said first amorphous perpendicular magnetization film is greater than the first perpendicular magnetic anisotropy energy of said first perpendicular magnetization film, and

further wherein, a thickness of the second amorphous perpendicular film and the first amorphous perpendicular film is less than a thickness of the perpendicular film, and

a total thickness of said first perpendicular magnetization film, the first amorphous perpendicular film and the second amorphous perpendicular film is within a range of 7 nm to 100 nm.

4. The perpendicular recording medium according to claim 3, wherein said first or second amorphous perpendicular magnetization film comprises TbFeCo.