Method of magnetic transfer to magnetic recording medium having two recording layers and the magnetic recording medium thereof
View Patent ↗A method of magnetic transfer allows transfer of magnetic signals independently to two recording layers included in a magnetic recording medium. The coercive force Hc 1 of an upper recording layer, the coercive force Hc 2 of a lower recording layer formed below the upper recording layer, the strength Hex 2 of a first transfer magnetic field, and the strength Hex 1 of a second transfer magnetic field are set so that the following relations hold true: Hc 1< Hc 2 , Hex 1< Hex 2 , Hc 1< Hex 2 , and Hex 1< Hc 2 . The first transfer magnetic field Hex 2 is applied to the recording medium to transfer magnetization patterns exclusively to the lower recording layer and to uniformly magnetize the upper recording layer. The second transfer magnetic field Hex 1 is applied to the recording medium to transfer magnetization patterns exclusively to the upper recording layer 1 a , while keeping the magnetization patterns in the lower recording layer 1 b unaffected. A first and second master disks having different magnetization patterns can be applied to record different data in the upper and lower recording layers.
1. A method of magnetically transferring data to a magnetic recording medium comprising a first magnetic recording layer and a second magnetic recording layer below the first magnetic recording layer, the method comprising the steps of:
applying an initializing magnetic field parallel to the magnetic recording medium to magnetically initialize both the first and second recording layers;
positioning a first master disk in close proximity to or in close contact with the magnetic recording medium, the master disk comprising a nonmagnetic substrate comprising soft magnetic layers embedded in the surface portions thereof and shaped with respective line patterns or respective island patterns indicating first data; and
applying a first transfer magnetic field to the first master disk and the magnetic recording medium in the opposite direction of the initializing magnetic field to transfer the first data from the first master disk to the second magnetic recording layer.
2. The method according to claim 1 , further comprising the step of applying a second transfer magnetic field to the first master disk and the magnetic recording medium in the same direction of the initializing magnetic field to transfer the first data to the first magnetic recording layer.
3. The method according to claim 1 , further comprising the steps of:
positioning a second master disk in close proximity to or in close contact with the magnetic recording medium, the second master disk comprising a nonmagnetic substrate comprising soft magnetic layers embedded in the surface portion thereof and shaped with respective line patterns or respective island patterns indicating second data; and
applying a second transfer magnetic field to the second master disk and the magnetic recording medium in the same direction of the initializing magnetic field to transfer the second data to the first magnetic recording layer.
4. The method according to claim 2 , wherein the strength of the first transfer magnetic field and the strength of the second transfer magnetic field are different from each other.
5. The method according to claim 3 , wherein the strength of the first transfer magnetic field and the strength of the second transfer magnetic field are different from each other.
6. The method according to claim 1 , wherein the coercive force of the first magnetic recording layer and the coercive force of the second magnetic recording layer are different from each other.
7. The method according to claim 4 , wherein the coercive force (Hc 1 ) of the first magnetic recording layer, the coercive force (Hc 2 ) of the second magnetic recording layer, the strength (Hex 2 ) of the first transfer magnetic field and the strength (Hex 1 ) of the second transfer magnetic field are set so that the following relations hold true: Hc 1 <Hc 2 , Hex 1 <Hex 2 , Hc 1 <Hex 2 , and Hex 1 <Hc 2 .
8. The method according to claim 5 , wherein the coercive force (Hc 1 ) of the first magnetic recording layer, the coercive force (Hc 2 ) of the second magnetic recording layer, the strength (Hex 2 ) of the first transfer magnetic field and the strength (Hex 1 ) of the second transfer magnetic field are set so that the following relations hold true: Hc 1 <Hc 2 , Hex 1 <Hex 2 , Hc 1 <Hex 2 , and Hex 1 <Hc 2 .
9. The method according to claim 8 , wherein the first data are servo signals, and the patterns of the soft magnetic layers in the first master disk and the patterns of the soft magnetic layers in the second master disk are different from each other so that the servo signals recorded in the second magnetic recording layer are not erased during recording of the second data in the first magnetic recording layer.
10. The magnetic recording medium described in claim 1 , further comprising one or more isolation layers between the first magnetic recording layer and the second magnetic recording layer, the one or more isolation layers comprising a nonmagnetic material.