Perpendicular magnetic recording medium
View Patent ↗A magnetic recording layer is formed on an auxiliary magnetic layer in a perpendicular magnetic recording medium. The auxiliary magnetic layer has the axis of easy magnetization in the vertical direction perpendicular to the surface of a substrate. The perpendicular magnetic recording medium reliably allows establishment of the magnetization in the auxiliary magnetic layer in the vertical direction. When a magnetic flux flows along the vertical direction perpendicular to the surface of the magnetic recording layer, the magnetic flux flows across the magnetic recording layer in the vertical direction. The magnetization is thus reliably established in the magnetic recording layer in the vertical direction. The magnetic field of a stronger intensity is thus leaked out of the magnetic recording layer in the vertical direction.
1. A perpendicular magnetic recording medium comprising:
a substrate;
a magnetic recording layer having an axis of easy magnetization in a vertical direction perpendicular to a surface of the substrate; and
an auxiliary magnetic layer receiving the magnetic recording layer, said auxiliary magnetic layer having an axis of easy magnetization in the vertical direction,
wherein a product of a thickness and a residual magnetic flux density for said auxiliary magnetic layer is set equal to or smaller than one fifth a product of a thickness and a residual magnetic flux density for the magnetic recording layer.
2. The perpendicular magnetic recording medium according to claim 1 , wherein said auxiliary magnetic layer has a coercivity smaller than that of the magnetic recording layer.
3. The perpendicular magnetic recording medium according to claim 1 , wherein said auxiliary magnetic layer is made of a layered material including a magnetic film containing at least Co and a non-magnetic film containing at least an element selected from a group consisting of Pt, Pd, Au and Ag.
4. The perpendicular magnetic recording medium according to claim 1 , further comprising a soft magnetic underlayer receiving the auxiliary magnetic layer, said underlayer having an axis of easy magnetization in a planar direction parallel to the surface of the substrate.
5. The perpendicular magnetic recording medium according to claim 4 , wherein said auxiliary magnetic layer has a coercivity smaller than that of the magnetic recording layer.
6. The perpendicular magnetic recording medium according to claim 5 , wherein said auxiliary magnetic layer is made of a layered material including a magnetic film containing at least Co and a non-magnetic film containing at least an element selected from a group consisting of Pt, Pd, Au and Ag.
7. The perpendicular magnetic recording medium according to claim 1 , further comprising:
a non-magnetic layer receiving the auxiliary magnetic layer; and
a soft magnetic underlayer receiving the non-magnetic layer, said underlayer having an axis of easy magnetization in a planar direction parallel to the surface of the substrate.
8. The perpendicular magnetic recording medium according to claim 7 , wherein said auxiliary magnetic layer has a coercivity smaller than that of the magnetic recording layer.
9. The perpendicular magnetic recording medium according to claim 8 , wherein said auxiliary magnetic layer is made of a layered material including a magnetic film containing at least Co and a non-magnetic film containing at least an element selected from a group consisting of Pt, Pd, Au and Ag.