Perpendicular magnetic recording medium and magnetic storage apparatus
View Patent ↗An improved perpendicular magnetic recording medium and an improved magnetic storage apparatus are provided, which are suitable for high speed and high density magnetic recording. A magnetic under layer of a two-layered perpendicular magnetic recording medium includes three layers: a ferromagnetic layer; a non-magnetic layer; and a ferromagnetic layer, wherein the ferromagnetic layers are antiferromagnetically coupled with each other, thereby preventing a magnetic flux from a magnetic wall in a magnetic under layer from entering a read back head.
1. A perpendicular magnetic recording medium, comprising a non-magnetic substrate, a magnetic under layer, and a perpendicular magnetic layer, the perpendicular magnetic layer being provided on the non-magnetic substrate via the magnetic under layer, wherein
said magnetic under layer includes at least one non-magnetic layer sandwiched by adjacent ferromagnetic layers, and
magnetization of the two ferromagnetic layers adjacent to the non-magnetic layer of said magnetic under layer are antiferromagnetically coupled with each other.
2. A perpendicular magnetic recording medium, comprising a non-magnetic substrate, a magnetic under layer, and a perpendicular magnetic layer, the perpendicular magnetic layer being provided on the non-magnetic substrate via the magnetic under layer wherein
said magnetic under layer includes at least one non-magnetic layer sandwiched by adjacent ferromagnetic layers,
the non-magnetic layer of said magnetic under layer is a non-magnetic metal layer made of a material selected from the group consisting of Ru, Rh, Ir, Cr and an alloy thereof, and each of the ferromagnetic layers adjacent to the non-magnetic layer of said magnetic under layer is a magnetic layer made of a material selected from the group consisting of Co, Ni, Fe and an alloy thereof, and
magnetization of the two ferromagnetic layers adjacent to the non-magnetic layer of said magnetic under layer are antiferromagnetically coupled with each other.
3. A magnetic storage apparatus, comprising a perpendicular magnetic recording medium, driving means for driving said perpendicular magnetic recording medium, a magnetic head including a write section and a read back section, means for relatively moving said magnetic head with respect to said magnetic recording medium, and signal processing means for inputting a signal to said magnetic head and reading back an output signal from said magnetic head,
wherein said magnetic recording medium is a perpendicular magnetic recording medium comprising a non-magnetic substrate, a magnetic under layer, and a perpendicular magnetic layer, the perpendicular magnetic layer being provided on the non-magnetic substrate via the magnetic under layer, wherein said magnetic under layer includes at least one non-magnetic layer sandwiched by adjacent ferromagnetic layers, and magnetizations of the two ferromagnetic layers adjacent to the non-magnetic layer of said magnetic under layer are antiferromagnetically coupled with each other.
4. The magnetic storage apparatus according to claim 3 , wherein in said magnetic recording medium, the non-magnetic layer of said magnetic under layer is a non-magnetic metal layer made of a material selected from the group consisting of Ru, Rh, Ir, Cr and an alloy thereof, and each of the ferromagnetic layers adjacent to the non-magnetic layer of said magnetic under layer is a magnetic layer made of a material selected from the group consisting of Co, Ni, Fe and an alloy thereof.
5. The magnetic storage apparatus of claim 3 , wherein a thickness of said at least one non-magnetic layer is in the range of 0.1 nm and 1 nm.
6. The magnetic storage apparatus of claim 4 , wherein a thickness of said non-magnetic layer of said magnetic under layer is in the range of 0.1 nm and 1 nm.
7. The perpendicular magnetic recording medium of claim 1 , wherein said non-magnetic layer includes Ru.
8. The perpendicular magnetic recording medium of claim 2 , wherein said non-magnetic layer includes Ru.
9. The magnetic storage apparatus of claim 5 , wherein said non-magnetic layer includes Ru.
10. The magnetic storage apparatus of claim 6 , wherein said non-magnetic layer includes Ru.
11. The perpendicular magnetic recording medium of claim 1 , wherein the ferromagnetic layers are antiferromagnetically coupled to each other via said non-magnetic layer having a thickness of 0.1 nm to 1.0 nm.
12. The perpendicular magnetic recording medium of claim 2 , wherein the ferromagnetic layers are antiferromagnetically coupled to each other via said non-magnetic layer having a thickness of 0.1 nm to 1.0 nm.