Magnetic recording medium and cartridge
A magnetic recording medium is a magnetic recording medium having a tape shape and includes a substrate, an underlayer provided on the substrate, and a magnetic layer provided on the underlayer. The magnetic layer has a surface having an uneven shape, a height range ΔH obtained from statistical information of a height of the uneven shape is in a range of 4.00 nm≤ΔH≤10.00 nm, and a gradient range ΔA obtained from statistical information of a gradient of the uneven shape is in a range of 2.50 degrees ≤ΔA.
1. A magnetic recording medium with a tape shape comprising:
a substrate;
an underlayer provided on the substrate; and
a magnetic layer provided on the underlayer,
wherein the magnetic layer has a surface having an uneven shape,
a height range ΔH obtained from statistical information of a height of the uneven shape is in a range of 4.00 nm≤ΔH≤10.00 nm, and
a gradient range ΔA obtained from statistical information of a gradient of the uneven shape is in a range of 2.50 degrees ≤ΔA.
2. The magnetic recording medium according to claim 1 , wherein the gradient range ΔA is in a range of 2.50 degrees ≤ΔA≤5.00 degrees.
3. The magnetic recording medium according to claim 1 , wherein the height range ΔA is in a range of 4.00 nm≤ΔA≤8.50 nm.
4. The magnetic recording medium according to claim 1 ,
wherein the underlayer and the magnetic layer contain a lubricant, and
the amount S of oozing of the lubricant per unit area of 12.5 μm×9.3 μm on the surface of the magnetic layer in vacuum is in a range of 3.0 μm 2 ≤S≤6.5 μm 2 .
5. The magnetic recording medium according to claim 4 , wherein the lubricant contains fatty acids and fatty acid esters.
6. The magnetic recording medium according to claim 1 , wherein a friction coefficient ratio (μ B /μ A ) between a dynamic friction coefficient μ B obtained after full-scale recording/full-scale reproduction is performed twice and a dynamic friction coefficient μ A before the full-scale recording/full-scale reproduction is performed is less than 2.0.
7. The magnetic recording medium according to claim 1 , wherein a squareness ratio of the magnetic layer in a vertical direction of the magnetic recording medium is 65% or more.
8. The magnetic recording medium according to claim 1 , wherein an average thickness of the magnetic recording medium is 5.3 μm or less.
9. The magnetic recording medium according to claim 1 , wherein an average thickness of the magnetic layer is 80 nm or less.
10. The magnetic recording medium according to claim 1 , wherein an average thickness of the substrate is 4.4 μm or less.
11. The magnetic recording medium according to claim 1 ,
wherein the magnetic layer contains a magnetic powder, and
the average particle volume of the magnetic powder is 2500 nm 3 or less.
12. The magnetic recording medium according to claim 11 , wherein the average particle volume of the magnetic powder is 1600 nm 3 or less.
13. The magnetic recording medium according to claim 1 ,
wherein the magnetic layer contains a magnetic powder, and
the magnetic powder contains hexagonal ferrite, ε-iron oxide, or Co-containing spinel ferrite.
14. The magnetic recording medium according to claim 1 , wherein the magnetic layer includes five or more servo bands.
15. The magnetic recording medium according to claim 14 , wherein the magnetic layer includes nine or more servo bands.
16. The magnetic recording medium according to claim 14 , wherein a ratio of a total area of the five or more servo bands with respect to an area of the surface of the magnetic layer is 4.0% or less.
17. The magnetic recording medium according to claim 14 , wherein a width of the servo band is 95 μm or less.
18. The magnetic recording medium according to claim 1 ,
wherein the magnetic layer is configured to be able to form a plurality of data tracks, and
a width of the data track is 2000 nm or less.
19. The magnetic recording medium according to claim 1 , wherein the substrate contains polyester.
20. A cartridge comprising the magnetic recording medium according to claim 1 .