Magnetic recording medium

Patent metadata

Field	Value
Publication number	US-10424329-B2
Application number	US-201615208932-A
Country	US
Kind code	B2
Filing date	Jul 13, 2016
Priority date	Jun 5, 2013
Publication date	Sep 24, 2019
Grant date	Sep 24, 2019

Abstract

A magnetic recording medium includes a substrate, a seed layer, an under layer, and a perpendicular recording layer having a granular structure. (Ms·αδ1.5(1−Rs)0.33), Ms, and α satisfy (Ms·α·δ1.5(1−Rs)0.33)≤0.1 [μ·emu·(mm)−1.5], Ms≥450 [emu/cc], and α≥1.2. In the above formulas, Ms indicates a saturated magnetization amount, α indicates the gradient of a M-H loop around a coercive force Hc, δ indicates the thickness of the perpendicular recording layer, and Rs indicates a squareness ratio.

First claim

What is claimed is:

1. A magnetic recording tape comprising:
a substrate that is selected from the group consisting of polyester, a cellulose derivative, a vinyl-based resin, a polyimide, and a polyamide;
a seed layer having an amorphous state and including an alloy containing Ti and Cr, wherein the seed layer contacts the substrate;
an under layer including Ru, wherein the seed layer is between the substrate and the under layer, and wherein the seed layer suppresses an influence of O 2 and H 2 O adsorbed on the substrate and improves a crystalline orientation of the under layer; and
a perpendicular recording layer having a granular structure formed on the under layer,
wherein (Ms·α·δ 1.5 (1−Rs) 0.33 ), Ms, and α satisfy the following relations:
( Ms·α·δ 1.5 (1− Rs ) 0.33 )≤0.1 [μ·emu·(mm) −1.5 ]

Ms≥ 450 [emu/cc]
α≥1.2

wherein in the above formulas, Ms indicates a saturated magnetization amount, α indicates the gradient of a M-H loop around a coercive force Hc, δ indicates the thickness of the perpendicular recording layer, and Rs indicates a squareness ratio.

2. The magnetic recording tape according to claim 1 ,
wherein the seed layer has an amorphous state and includes a metal having a melting point of 2,000° C. or less.

3. The magnetic recording tape according to claim 1 ,
wherein (Ku·V/k B ·T) satisfies the following relation:
( Ku·V/k B ·T )≥65, and

wherein in the above formula, Ku indicates magnetic anisotropy energy, V indicates an activation volume, k B indicates Boltzmann constant, and T indicates the absolute temperature.

4. The magnetic recording tape according to claim 1 ,
wherein the perpendicular recording layer has a granular structure in which grains containing Co, Pt, and Cr are separated from each other with oxides provided therebetween.

5. The magnetic recording tape according to claim 4 ,
wherein the perpendicular recording layer has an average composition represented by the following formula (1):
(Co x Pt y Cr 100-x-y ) 100-z —(SiO 2 ) z   (1), and

wherein in the formula (1), x, y, and z satisfy 69≤x≤72, 12≤y≤16, and 9≤z≤12, respectively.

6. The magnetic recording tape according to claim 1 , wherein a thickness of the magnetic recording tape is between 5 nm and 20 nm.

7. The magnetic recording tape according to claim 1 , wherein the seed layer includes an alloy containing Ti, Cr, and O.

8. The magnetic recording tape according to claim 7 , wherein the seed layer further contains 15 atomic % or less of O and more than 0 atomic % of O.

9. The magnetic recording tape according to claim 1 , wherein the seed layer contains at least 30 atomic % of Ti.

10. The magnetic recording tape according to claim 1 , wherein the under layer has a crystalline structure similar to that of the perpendicular recording layer.

11. The magnetic recording tape according to claim 1 , wherein the under layer is a Ru element or a Ru alloy.

12. The magnetic recording tape according to claim 11 , wherein the Ru alloy is a Ru alloy oxide.

13. The magnetic recording tape according to claim 11 , wherein the Ru alloy is Ru—SiO 2 , Ru—TiO 2 , or Ru—ZrO 2 .

14. The magnetic recording tape according to claim 1 , wherein the seed layer comprises oxygen.

15. The magnetic recording tape according to claim 14 , wherein the seed layer contains 15 atomic % or less of oxygen and more than 0 atomic % of O.

Assignees

• Sony Corp

Inventors

• Tachibana Junichi
• Sekiguchi Noboru
• Ozaki Tomoe

Classifications

• G11B5/7379

  Seed layer, e.g. at least one non-magnetic layer is specifically adapted as a seed or seeding layer · CPC title

• G11B5/78

  Tape carriers · CPC title

• G11B5/65

  characterised by its composition (G11B5/66 takes precedence) · CPC title

• G11B5/64

  comprising only the magnetic material without bonding agent · CPC title

• G11B5/7315

  Physics · mapped topic