Patent ID: 8213119

Claim:
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 [S 1 ; S 2 ] comprising a magnetic state (S 1 ) and a magnetic state (S 2 ) 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 magnetic states (S 1 ) and (S 2 ) are independent of each other, wherein the first magnetic island and the second magnetic island have a magnetic easy axis respectively oriented at a first tilt angle (α 1 ) and a second tilt angle (α 2 ) with respect to the X direction, wherein both α 1 and α 2 differ from 0, 90, 180, and 270 degrees, wherein the first magnetic island and the second magnetic island have a magnetic hard axis respectively oriented at a first tilt angle (α 1 *) and a second tilt angle (α 2 *) with respect to the X direction, and wherein −90<α 1 *<0 and/or −90<α 2 *<0; identifying the magnetization state [S 1 ; S 2 ] by decoding the readback waveform W resulting from said reading; and displaying and/or recording the magnetization state [S 1 ; S 2 ], wherein the magnetization state [S 1 ; S 2 ] 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 S 1 is respectively +1 or −1 if a magnetization of the first magnetic island is oriented at or opposite to the angle α 1 , and wherein the magnetic state S 2 is respectively +1 or −1 if a magnetization of the second magnetic island is oriented at or opposite to the angle α 2 .