Magnetic recording medium with a non-magnetic granular layer under a plurality of granular magnetic layers and storage apparatus

1. A magnetic recording medium comprising:

a non-magnetic granular layer; and

a recording layer provided on the non-magnetic granular layer,

wherein the recording layer includes a first granular magnetic layer provided on the non-magnetic granular layer, and a second granular magnetic layer provided on the first granular magnetic layer, and

wherein a non-magnetic material magnetically separating metal grains of the non-magnetic granular layer is different from a non-magnetic material magnetically separating magnetic grains of the first granular magnetic layer,

wherein an oxide material having a maximum content in each of the non-magnetic granular layer, the first granular layer, and the second granular layer magnetic layer are all different, and

wherein a non-magnetic material used for magnetic separation in each of the non-magnetic granular layer, the first granular magnetic layer, and the second granular magnetic layer consists of a single oxide selected from the group consisting of SiO 2 , TiO 2 , and Cr 2 O 3 .

2. The magnetic recording medium as claimed in claim 1 , wherein the non-magnetic material magnetically separating the magnetic grains of the first granular magnetic layer is different from a non-magnetic material magnetically separating magnetic grains of the second granular magnetic layer.

3. The magnetic recording medium as claimed in claim 1 , at least one of the first granular magnetic layer and the second granular magnetic layer has a hard magnetic characteristic and a magnetic anisotropy constant Ku of 2×10 6 erg/cc or greater.

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

a soft magnetic back layer formed by a soft magnetic material; and

an intermediate layer formed by Ru or a Ru alloy and provided on the soft magnetic back layer,

wherein the non-magnetic granular layer is provided on the intermediate layer.

5. The magnetic recording medium as claimed in claim 4 , further comprising:

at least one third granular magnetic layer provided above the second granular magnetic layer.

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

a coupling control layer provided between the second granular magnetic layer and the at least one third granular magnetic layer.

7. A storage apparatus comprising:

at least one magnetic recording medium; and

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

wherein the magnetic recording medium comprises:

a non-magnetic granular layer; and

a recording layer provided on the non-magnetic granular layer,

wherein the recording layer includes a first granular magnetic layer provided on the non-magnetic granular layer, and a second granular magnetic layer provided on the first granular magnetic layer, and

wherein a non-magnetic material magnetically separating metal grains of the non-magnetic granular layer is different from a non-magnetic material magnetically separating magnetic grains of the first granular magnetic layer,

wherein an oxide material having a maximum content in each of the non-magnetic granular layer, the first granular layer, and the second granular layer magnetic layer are all different, and

wherein a non-magnetic material used for magnetic separation in each of the non-magnetic granular layer, the first granular magnetic layer, and the second granular magnetic layer consists of a single oxide selected from the group consisting of SiO 2 , TiO 2 , and Cr 2 O 3 .

8. The storage apparatus as claimed in claim 7 , wherein the non-magnetic material magnetically separating the magnetic grains of the first granular magnetic layer is different from a non-magnetic material magnetically separating magnetic grains of the second granular magnetic layer.

9. The storage apparatus as claimed in claim 7 , at least one of the first granular magnetic layer and the second granular magnetic layer has a hard magnetic characteristic and a magnetic anisotropy constant Ku of 2×10 6 erg/cc or greater.

10. The storage apparatus as claimed in claim 7 , wherein the magnetic recording medium further comprises:

a soft magnetic back layer formed by a soft magnetic material; and

an intermediate layer formed by Ru or a Ru alloy and provided on the soft magnetic back layer,

wherein the non-magnetic granular layer is provided on the intermediate layer.