Magnetic recording medium and magnetic storage apparatus

1. A magnetic recording medium comprising:

a substrate;

a magnetic layer including an alloy having an L1 0 type crystal structure as a main component thereof; and

a plurality of underlayers that are successively stacked and are arranged between the substrate and the magnetic layer,

wherein the plurality of underlayers include at least one crystalline underlayer which has a (100) orientation, and includes W as a main component thereof and one or more kinds of elements selected from a group consisting of Fe, Ni, Co, Hf, Zr, Y, Be, Ce, La, and Sc.

2. The magnetic recording medium as claimed in claim 1 , wherein the at least one crystalline underlayer further includes one or more kinds of elements selected from a group consisting of Mn, Ta, Nb, Ti, Cr, V, and Mo.

3. The magnetic recording medium as claimed in claim 1 , wherein a total content of the one or more kinds of elements selected from the group consisting of Fe, Ni, Co, Hf, Zr, Y, Be, Ce, La, and Sc is within a range of 1 at % to 40 at %.

4. The magnetic recording medium as claimed in claim 1 , wherein

the plurality of underlayers include an orientation control underlayer including one or more kinds of metals or alloys selected from a group consisting of Cr, alloys having a BCC (Body Centered Cubic) structure and including Cr as a main component thereof, and alloys having a B2 structure, and

the at least one crystalline underlayer is provided on the orientation control underlayer.

5. The magnetic recording medium as claimed in claim 1 , further comprising:

a barrier layer arranged between the at least one crystalline underlayer and the magnetic layer,

wherein the barrier layer is made of one or more kinds of compounds selected from a group consisting of MgO, TiO, NiO, TiN, TaN, HfN, NbN, ZrC, HfC, TaC, NbC, and TiC.

6. The magnetic recording medium as claimed in claim 1 , wherein the magnetic layer includes an FePt alloy or a CoPt alloy having the L1 0 type crystal structure as the main component thereof, and includes one or more kinds of materials selected from a group consisting of SiO 2 , TiO 2 , Cr 2 O 3 , Al 2 O 3 , Ta 2 O 5 , ZrO 2 , Y 2 O 3 , CeO 2 , MnO, TiO, ZnO, B 2 O 3 , C, B, and BN.

7. A magnetic storage apparatus comprising:

a magnetic recording medium; and

a head configured to write information on and read information from the magnetic recording medium,

wherein the magnetic recording medium includes

a substrate;

a magnetic layer including an alloy having an L1 0 type crystal structure as a main component thereof; and

a plurality of underlayers that are successively stacked and are arranged between the substrate and the magnetic layer,

wherein the plurality of underlayers include at least one crystalline underlayer which has a (100) orientation, and includes W as a main component thereof and one or more kinds of elements selected from a group consisting of Fe, Ni, Co, Hf, Zr, Y, Be, Ce, La, and Sc.

8. The magnetic storage apparatus as claimed in claim 7 , wherein the at least one crystalline underlayer of the magnetic recording medium further includes one or more kinds of elements selected from a group consisting of Mn, Ta, Nb, Ti, Cr, V, and Mo.

9. The magnetic storage apparatus as claimed in claim 7 , wherein a total content of the one or more kinds of elements selected from the group consisting of Fe, Ni, Co, Hf, Zr, Y, Be, Ce, La, and Sc is within a range of 1 at % to 40 at %.

10. The magnetic storage apparatus as claimed in claim 7 , wherein

the plurality of underlayers of the magnetic recording medium include an orientation control underlayer including one or more kinds of metals or alloys selected from a group consisting of Cr, alloys having a BCC (Body Centered Cubic) structure and including Cr as a main component thereof, and alloys having a B2 structure, and

the at least one crystalline underlayer is provided on the orientation control underlayer.

11. The magnetic storage apparatus as claimed in claim 7 , wherein the magnetic recording medium further includes

a barrier layer arranged between the at least one crystalline underlayer and the magnetic layer,

wherein the barrier layer is made of one or more kinds of compounds selected from a group consisting of MgO, TiO, NiO, TiN, TaN, HfN, NbN, ZrC, HfC, TaC, NbC, and TiC.

12. The magnetic storage apparatus as claimed in claim 7 , wherein the magnetic layer of the magnetic recording medium includes an FePt alloy or a CoPt alloy having the L1 0 type crystal structure as the main component thereof, and includes one or more kinds of materials selected from a group consisting of SiO 2 , TiO 2 , Cr 2 O 3 , Al 2 O 3 , Ta 2 O 5 , ZrO 2 , Y 2 O 3 , CeO 2 , MnO, TiO, ZnO, B 2 O 3 , C, B, and BN.

13. The magnetic recording medium as claimed in claim 1 , further comprising:

a seed layer made of a Cr alloy and provided on the substrate,

wherein the plurality of underlayers include an orientation control layer made of Cr or a Cr alloy and provided on the seed layer, the at least one crystalline underlayer provided on the orientation control layer, and a barrier layer made of one or more kinds of compounds selected from a group consisting of MgO, TiO, NiO, TiN, TaN, HfN, NbN, ZrC, HfC, TaC, NbC, and TiC and provided on the at least one crystalline underlayer, and

wherein the magnetic layer is provided on the barrier layer.

14. The magnetic recording medium as claimed in claim 1 , further comprising:

a barrier layer arranged between the at least one crystalline underlayer and the magnetic layer,

wherein the barrier layer is made of one or more kinds of compounds selected from a group consisting of MgO, TiO, NiO, TiN, TaN, HfN, NbN, ZrC, HfC, TaC, NbC, and TiC,

wherein the plurality of underlayers include an orientation control underlayer including one or more kinds of metals or alloys selected from a group consisting of Cr, alloys having a BCC (Body Centered Cubic) structure and including Cr as a main component thereof, and alloys having a B2 structure, and

wherein the at least one crystalline underlayer is provided on the orientation control underlayer.

15. The magnetic storage apparatus as claimed in claim 7 , wherein the magnetic recording medium further includes

a seed layer made of a Cr alloy and provided on the substrate,

wherein the plurality of underlayers include an orientation control layer made of Cr or a Cr alloy and provided on the seed layer, the at least one crystalline underlayer provided on the orientation control layer, and a barrier layer made of one or more kinds of compounds selected from a group consisting of MgO, TiO, NiO, TiN, TaN, HfN, NbN, ZrC, HfC, TaC, NbC, and TiC and provided on the at least one crystalline underlayer, and

wherein the magnetic layer is provided on the barrier layer.

16. The magnetic storage apparatus as claimed in claim 7 , wherein the magnetic recording medium further includes

a barrier layer arranged between the at least one crystalline underlayer and the magnetic layer,

wherein the barrier layer is made of one or more kinds of compounds selected from a group consisting of MgO, TiO, NiO, TiN, TaN, HfN, NbN, ZrC, HfC, TaC, NbC, and TiC,

wherein the plurality of underlayers include an orientation control underlayer including one or more kinds of metals or alloys selected from a group consisting of Cr, alloys having a BCC (Body Centered Cubic) structure and including Cr as a main component thereof, and alloys having a B2 structure, and

wherein the at least one crystalline underlayer is provided on the orientation control underlayer.

17. The magnetic recording medium as claimed in claim 1 , wherein the magnetic layer has a coercivity higher than 36 kOe.

18. The magnetic storage apparatus as claimed in claim 7 , wherein the magnetic layer of the magnetic recording medium has a coercivity higher than 36 kOe.