IP Library Granted Patent US 12676168
Granted Patent B2
US 12676168 · App. 19/113,131 · Granted Jul 7, 2026

Magnetic recording medium and cartridge

Inventors: Minoru Yamaga (Tokyo, JP); Yuuko Kamoshita (Tokyo, JP)
Assignee: Sony Group Corporation
G11B5/78G11B5/70678G11B5/714G11B5/7367
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Quick Facts
Patent No.
US 12676168
App. No.
19/113,131
Granted
Jul 7, 2026
Kind
B2
Abstract

To provide a magnetic recording medium with which excellent electromagnetic conversion characteristics can be obtained. A magnetic recording medium is a tape-type magnetic recording medium and includes a base body and a magnetic layer. An average thickness of the magnetic recording medium is 5.30 μm or less. When a power spectral density at each position of spatial wavelength λ n =100/n [μm] (provided that n is an integer of 1 or more and 255 or less) is obtained using a 2D surface profile image of a measurement range of 100 [μm]×100 [μm], that has been acquired by measuring a surface on a side of the magnetic layer by an atomic force microscope, a ratio I λn≤5 /I 10≤λn≤20 between an average value I λn≤5 of integrated values of the power spectral density within a range of spatial wavelength λ n ≤5 μm and an average value I 10≤λn≤20 of integrated values of the power spectral density within a range of 10 μm≤spatial wavelength λ n ≤20 μm is 3.00 or less. An average value of a kurtosis on the surface on the side of the magnetic layer is 5.50 or less.

Claims (52)

1 . A tape-type magnetic recording medium, comprising:

a base body; and

a magnetic layer, wherein

an average thickness of the magnetic recording medium is 5.30 μm or less,

when a power spectral density at each position of spatial wavelength λ n =100/n [μm] (provided that n is an integer of 1 or more and 255 or less) is obtained using a 2D surface profile image of a measurement range of 100 [μm]×100 [μm], that has been acquired by measuring a surface on a side of the magnetic layer by an atomic force microscope, a ratio I λn≤5 /I 10≤λn≤20 between an average value I λn≤5 of integrated values of the power spectral density within a range of spatial wavelength λ n ≤5 μm and an average value I 10≤λn≤20 of integrated values of the power spectral density within a range of 10 μm≤spatial wavelength λ n ≤20 μm is 3.00 or less, and

an average value of a kurtosis on the surface on the side of the magnetic layer is 5.50 or less.

2 . The magnetic recording medium according to claim 1 , wherein

the ratio I λn≤5 /I 10≤λn≤20 is 2.80 or less.

3 . The magnetic recording medium according to claim 1 , wherein

the ratio I λn≤5 /I 10≤λn≤20 is 2.10 or less.

4 . The magnetic recording medium according to claim 1 , wherein

the average value I λn≤5 of the integrated values is 2.20 nm 2 or less.

5 . The magnetic recording medium according to claim 1 , wherein

the average value I 10≤λn≤20 of the integrated values is 0.70 nm 2 or less.

6 . The magnetic recording medium according to claim 1 , wherein

the average value I 10≤λn≤20 of the integrated values is 0.65 nm 2 or more.

7 . The magnetic recording medium according to claim 1 , wherein

the average value of the kurtosis on the surface on the side of the magnetic layer is 3.30 or more and 5.50 or less.

8 . The magnetic recording medium according to claim 1 , wherein

the average value of the kurtosis on the surface on the side of the magnetic layer is 3.80 or more and 5.50 or less.

9 . The magnetic recording medium according to claim 1 , wherein

the average value of the kurtosis on the surface on the side of the magnetic layer is 3.80 or more and 4.80 or less.

10 . The magnetic recording medium according to claim 1 , wherein

an average value of a root mean square roughness on the surface on the side of the magnetic layer is 2.25 nm or less.

11 . The magnetic recording medium according to claim 1 , wherein

the magnetic layer includes a servo pattern, the servo pattern includes a plurality of first magnetization areas and a plurality of second magnetization areas, and

the plurality of first magnetization areas and the plurality of second magnetization areas are asymmetric with respect to an axis parallel to a width direction of the magnetic recording medium.

12 . The magnetic recording medium according to claim 11 , wherein

a tilt angle of the first magnetization areas with respect to the axis and a tilt angle of the second magnetization areas with respect to the axis differ, and

a larger one of the tilt angle of the first magnetization areas or the tilt angle of the second magnetization areas is 18° or more and 28° or less.

13 . The magnetic recording medium according to claim 1 , wherein

the magnetic layer is configured to be capable of recording signals at a data track width of 850 nm or less and a bit length of 47 nm or less.

14 . The magnetic recording medium according to claim 1 , further comprising:

an underlayer, wherein

an average thickness of the underlayer is 0.90 μm or less.

15 . The magnetic recording medium according to claim 1 , wherein

an average thickness of the magnetic layer is 0.08 μm or less.

16 . The magnetic recording medium according to claim 1 , wherein

an average thickness of the base body is 4.40 μm or less.

17 . The magnetic recording medium according to claim 1 , wherein

the magnetic layer contains magnetic particles, and

an average particle volume of the magnetic particles is 1500 nm 3 or less.

18 . The magnetic recording medium according to claim 1 , wherein

the magnetic layer contains magnetic particles, and

the magnetic particles contain hexagonal ferrite, ε iron oxide, or Co-containing spinel ferrite.

19 . A cartridge, comprising:

the magnetic recording medium according to claim 1 .

20 . A tape-type magnetic recording medium, comprising:

a base body; and

a magnetic layer, wherein

an average thickness of the magnetic recording medium is 5.30 μm or less, and

when a power spectral density at each position of spatial wavelength λ n =100/n [μm] (provided that n is an integer of 1 or more and 255 or less) is obtained using a 2D surface profile image of a measurement range of 100 [μm]×100 [μm], that has been acquired by measuring a surface on a side of the magnetic layer by an atomic force microscope, a ratio I λn≤5 /I 10≤λn≤20 between an average value I λn≤5 of integrated values of the power spectral density within a range of spatial wavelength λ n ≤5 μm and an average value I 10≤λn≤20 of integrated values of the power spectral density within a range of 10 μm≤spatial wavelength λ n ≤20 μm is 3.00 or less.