Writing and reading multi-level patterned magnetic recording media

A method for reading magnetization states from a two-level patterned magnetic medium comprising a plurality of pillars distributed in an X direction and a Y direction which are orthogonal to each other and define an X-Y plane, consecutive pillars of the plurality of pillars separated by non-magnetic material, each pillar comprising two magnetic islands distributed along a Z direction orthogonal to the X-Y plane, said method comprising:

• reading, by a magnetic read head moving in the X direction, a readback waveform (W) specific to a magnetization state [S1;
• S2] comprising a magnetic state (S1) and a magnetic state (S2) in a first magnetic island and in a second magnetic island, respectively, of the two magnetic islands of a selected pillar of the plurality of pillars, wherein the first magnetic island and the second magnetic island have a magnetic easy axis respectively oriented at a first tilt angle (α1) and a second tilt angle (α2) with respect to the X direction, wherein α1 and α2 satisfy a condition selected from the group consisting of 1) α1≠α2, 2) either or both of α1 and α2 differing from 0, 90, 180, and 270 degrees, and 3) combinations thereof, and wherein the first magnetic island and the second magnetic island have a magnetic hard axis respectively oriented at a first tilt angle (α1*) and a second tilt angle (α2*) with respect to the X direction;
• identifying the magnetization state [S1;
• S2] by decoding the readback waveform W resulting from said reading;
• and
• displaying and/or recording the magnetization state [S1;
• S2],
• wherein the magnetization state [S1;
• S2] is a state A=[+1,+1], a state B=[−1,−1], a state C=[+1,−1], or a state D=[−1,+1], wherein the magnetic state S1 is respectively +1 or −1 if a magnetization of the first magnetic island is oriented at or opposite to the angle α1, and wherein the magnetic state S2 is respectively +1 or −1 if a magnetization of the second magnetic island is oriented at or opposite to the angle α2.

An apparatus comprising a computer program product, said computer program product comprising a computer readable storage medium having a computer readable program code embodied therein, said computer readable program code containing instructions that when executed by a processor of a computer system implement a method for writing magnetization states in a multi-level patterned magnetic medium comprising a plurality of pillars distributed in an X direction and a Y direction which are orthogonal to each other and define an X-Y plane, consecutive pillars of the plurality of pillars separated by non-magnetic material, each pillar comprising a plurality of magnetic islands distributed along a Z direction orthogonal to the X-Y plane, said method comprising:

• selecting a magnetization state [S1;
• S2] comprising a magnetic state (S1) and a magnetic state (S2) in a first magnetic island and in a second magnetic island, respectively, of the plurality of magnetic islands of a first pillar of the plurality of pillars, wherein α1* and α2* are a first tilt angle and a second tilt angle at which a hard axis of the first magnetic island and the second magnetic island are respectively oriented with respect to the X direction, and wherein either or both of α1* and α2* are in a range of 0 to −90 degrees;
• determining a write current (I) sufficient to write the magnetization state [S1;
• S2];
• and
• issuing a command for applying the write current I to a magnetic write head moving in the X direction to generate in the first magnetic island and the second magnetic island a magnetic field that exceeds a switching field of the first magnetic island and a switching field of the second magnetic island, respectively, said command causing the magnetic write head to write the magnetization state [S1;
• S2] by simultaneously writing the magnetic state S1 in the first magnetic island and the magnetic state S2 in the second magnetic island.

An apparatus comprising a computer program product, said computer program product comprising a computer readable storage medium having a computer readable program code embodied therein, said computer readable program code containing instructions that when executed by a processor of a computer system implement a method for reading magnetization states from a multi-level patterned magnetic medium comprising a plurality of pillars distributed in an X direction and a Y direction which are orthogonal to each other and define an X-Y plane, consecutive pillars of the plurality of pillars separated by non-magnetic material, each pillar comprising two magnetic islands distributed along a Z direction orthogonal to the X-Y plane, said method comprising:

• issuing a command for reading, by a magnetic read head moving in the X direction, a readback waveform (W) specific to a magnetization state [S1;
• S2] comprising a magnetic state (S1) and a magnetic state (S2) in a first magnetic island and in a second magnetic island, respectively, of the two islands of a selected pillar of the plurality of pillars, said command causing the magnetic write head to read the readback waveform W, wherein the first magnetic island and the second magnetic island have a magnetic easy axis respectively oriented at a first tilt angle (α1) and a second tilt angle (α2) with respect to the X direction, wherein α1 and α2 satisfy a condition selected from the group consisting of α1≠α2, either or both of α1 and α2 differing from 0, 90, 180, and 270 degrees, and combinations thereof, and wherein the first magnetic island and the second magnetic island have a magnetic hard axis respectively oriented at a first tilt angle (α1*) and a second tilt angle (α2*) with respect to the X direction;
• identifying the magnetization state [S1;
• S2] by decoding the readback waveform W resulting from said reading;
• and
• displaying and/or recording the magnetization state [S1;
• S2],
• wherein the magnetization state [S1;
• S2] is a state A=[+1,+1], a state B=[−1,−1], a state C=[+1,−1], or a state D=[−1,+1], wherein the magnetic state S1 is respectively +1 or −1 if a magnetization of the first magnetic island is oriented at or opposite to the angle α1, and wherein the magnetic state S2 is respectively +1 or −1 if a magnetization of the second magnetic island is oriented at or opposite to the angle α2.