Perpendicular magnetic recording medium and the method of manufacturing the same
View Patent ↗A perpendicular magnetic recording medium includes a soft magnetic backing layer, an underlayer, a nonmagnetic intermediate layer, and a magnetic recording layer sequentially deposited on a nonmagnetic substrate. The underlayer can contain cobalt, nickel, and iron and have an fcc structure and exhibit soft magnetic property. The underlayer preferably contains nickel in a range of 30 to 88 at % and iron in a range of 0.1 to 22 at %. The underlayer can further contain Si, B, Nb, N, Ta, Al, Pd, Cr, or Mo. The nonmagnetic intermediate layer preferably contains at least one element selected from Ru, Re, Pd, Ir, Pt, and Rh. The magnetic recording layer preferably has a granular structure. A seed layer can be further provided between the soft magnetic backing layer and the underlayer.
1. A perpendicular magnetic recording medium comprising:
a soft magnetic backing layer, a seed layer, an underlayer, a nonmagnetic intermediate layer, and a magnetic recording layer sequentially disposed on a nonmagnetic substrate,
wherein the underlayer consists essentially of cobalt, nickel, iron, and at least one other element selected from a group consisting of Si, B, and Nb,
wherein the underlayer has an fcc structure and exhibits soft magnetic property,
wherein the underlayer has crystal grains and grain boundaries that isolate the crystal grains from each other to control grain size of the magnetic recording layer and to promote magnetic isolation between crystal grains of the magnetic recording layer,
wherein the underlayer contains nickel in a range of 30 at % to 88 at % and iron in a range of 0.1 at % to 22 at %,
wherein the underlayer has a thickness of at most 30 nm,
wherein the nonmagnetic intermediate layer contains at least one element selected from a group consisting of Ru, Re, Pd, Ir, Pt, and Rh, and
wherein the seed layer contains at least one element selected from a group consisting of Ta, Ti, Zr, Cr, Mo, W, Si, Al, Pd, and Pt.
2. The perpendicular magnetic recording medium according to claim 1 , wherein the nonmagnetic intermediate layer has a thickness of at most 20 nm.
3. The perpendicular magnetic recording medium according to claim 1 , wherein the underlayer exhibits a coercivity of at most 10 kA/m.
4. The perpendicular magnetic recording medium according to claim 1 , wherein the seed layer has a thickness of at most 5 nm.
5. The perpendicular magnetic recording medium according to claim 1 , wherein the magnetic recording layer has a granular structure in which magnetic crystal grains are dispersed in a matrix of nonmagnetic oxide or nonmagnetic nitride.
6. A method of manufacturing a perpendicular magnetic recording medium comprising the steps of:
providing a nonmagnetic substrate; and
sequentially depositing a soft magnetic backing layer, a seed layer, an underlayer, a nonmagnetic intermediate layer, and a magnetic recording layer on one side of the nonmagnetic substrate,
wherein the underlayer consists essentially of cobalt, nickel, iron, and at least one other element selected from a group consisting of Si, B, and Nb,
wherein the underlayer has an fcc structure and exhibits soft magnetic property,
wherein the underlayer has crystal grains and grain boundaries that isolate the crystal grains from each other to control grain size of the magnetic recording layer and to promote magnetic isolation between crystal grains of the magnetic recording layer, and
wherein the underlayer contains nickel in a range of 30 at % to 88 at % and iron in a range of 0.1 at % to 22 at %,
wherein the underlayer has a thickness of at most 30 nm,
wherein the nonmagnetic intermediate layer contains at least one element selected from a group consisting of Ru, Re, Pd, Ir, Pt, and Rh, and
wherein the seed layer contains at least one element selected from a group consisting of Ta, Ti, Zr, Cr, Mo, W, Si, Al, Pd, and Pt.
7. The method of claim 6 , wherein the soft magnetic backing layer, the seed layer, the underlayer, the nonmagnetic intermediate layer, and the magnetic recording layer are deposited without heating.
8. The perpendicular magnetic recording medium according to claim 1 , wherein the soft magnetic backing layer is selected from a group consisting of crystalline alloy, Sendust alloy, and amorphous cobalt alloy.
9. The method according to claim 6 , wherein the soft magnetic backing layer is selected from a group consisting of crystalline alloy, Sendust alloy, and amorphous cobalt alloy.