Magnetic recording medium with CR <110> preferred growth along a predetermined direction, method of producing the same and magnetic storage apparatus
View Patent ↗A magnetic recording medium including a textured surface that is textured in a predetermined direction. The textured surface preferably has a distance λ between two mutually adjacent texturing lines satisfying a relationship 5<λ<30 nm, and an angle φ between the textured surface and an oblique texture plane satisfying a relationship 0.5<φ<7 degrees. There is also a Cr-based underlayer provided on the textured surface that has a preferred growth so that a number of grains having Cr<110> in a vicinity of 0 degrees or 90 degrees with respect to the predetermined direction is two times or greater than a number of grains having Cr<110> in a vicinity of 45 degrees with respect to the predetermined direction. Additionally, there is also a Co-based magnetic layer provided on the underlayer that has Co(1120) preferred growth along the predetermined direction.
1. A magnetic recording medium comprising:
a textured surface that is textured in a predetermined direction, said textured surface having a distance λ between two mutually adjacent texturing lines satisfying a relationship 5<λ<30 nm, and an angleφ between the textured surface and an oblique texture plane satisfying a relationship 0.5<φ<7 degrees;
a Cr-based underlayer provided on the textured surface and having a preferred growth so that a number of grains having Cr<110> in a vicinity of 0 degrees or 90 degrees with respect to the predetermined direction is two times or greater than a number of grains having Cr<110> in a vicinity of 45 degrees with respect to the predetermined direction; and
a Co-based magnetic layer provided on the underlayer and having Co(1120) preferred growth along the predetermined direction.
2. The magnetic recording medium as claimed in claim 1 , wherein the textured surface is formed by a mechanically textured surface of a seed layer that is made of a material selected from a group consisting of NiP, CrNiZr, CoNbZr and NiAl.
3. The magnetic recording medium as claimed in claim 1 , wherein the underlayer is made of a material selected from a group consisting of Cr, CrMo, CrMoW, CrV and CrW, where an Mo-content is greater than or equal to 1 at %, a W-content is less than or equal to 30 at %, and a V-content is less than or equal to 30 at %.
4. The magnetic recording medium as claimed in claim 1 , wherein the magnetic layer is made of a material selected from a group consisting of CoCrPtB, CoCrPt, CoCrTa, CoCrPtTa, CoCrPtTaB and CoCrPtBCu.
5. The magnetic recording medium as claimed in claim 1 , further comprising:
a CoCr-based intermediate layer provided between the underlayer and the magnetic layer, where a Cr-content is greater than or equal to 25 at % and is less than or equal to 45 at %.
6. The magnetic recording medium as claimed in claim 1 , wherein the magnetic recording medium has a disk shape, and the predetermined direction is a circumferential direction of the disk shape.
7. The magnetic recording medium as claimed in claim 1 , wherein the underlayer has a thickness greater than approximately 2 nm and less than approximately 15 nm.
8. A magnetic storage apparatus comprising at least one magnetic recording medium, the magnetic recording medium including:
a textured surface that is textured in a predetermined direction, said textured surface having a distance λ between two mutually adjacent texturing lines satisfying a relationship 5<λ<30 nm, and an angle φ between the textured surface and an oblique texture plane satisfying a relationship 0.5<φ7 degrees;
a Cr-based underlayer provided on the textured surface and having a preferred growth so that a number of grains having Cr<110> in a vicinity of 0 degrees or 90 degrees with respect to the predetermined direction is two times or greater than a number of grains having Cr<110> in a vicinity of 45 degrees with respect to the predetermined direction; and
a Co-based magnetic layer provided on the underlayer and having Co(1120) preferred growth along the predetermined direction.
9. A method of producing a magnetic recording medium, comprising the steps of:
(a) forming a textured surface that is textured in a predetermined direction, said textured surface having a distance λ between two mutually adjacent texturing lines satisfying a relationship 5<λ<30 nm, and an angle φ between the textured surface and an oblique texture plane satisfying a relationship 0.5 <φ<7 degrees;
(b) forming a Cr-based underlayer provided on the textured surface and having a preferred growth so that a number of grains having Cr<110> in a vicinity of 0 degrees or 90 degrees with respect to the predetermined direction is two times or greater than a number of grains having Cr<110> in a vicinity of 45 degrees with respect to the predetermined direction; and
(c) forming a Co-based magnetic layer provided on the underlayer and having Co(1120) preferred growth along the predetermined direction.
10. The method of producing the magnetic recording medium as claimed in claim 9 , wherein said step (b) forms the underlayer by a dc sputtering at a substrate temperature Ts satisfying 150° C.<Ta<260° C., and a substrate bias voltage Vb satisfying −50 V<Vb<−250 V.