Patent ID: 7368301

Claim:
A method of selectively writing to a plurality of toggle MTJ cells formed along a word line in a MRAM array wherein said toggle MTJ cells are formed between an array of bit line segments and said word line, and are comprised of a SAF free layer having a plurality of “n” magnetic sub-layers with equal magnetic moments but different anisotropies wherein “n” is an even integer, an anti-parallel coupling layer between adjacent magnetic sub-layers, and an easy axis parallel to a bit line segment and normal to said word line, comprising: (a) applying a first current pulse in said word line during a first time interval, said first current pulse generates a magnetic field larger than a spin-flop field for the SAF free layer with sufficient margin to write a “1” memory state in the SAF free layer in each of the plurality of toggle MTJ cells; (b) reducing the first current pulse to zero in a second time interval that immediately follows the first time interval; (c) applying a second pulse in the word line current that is equal and opposite the first current pulse during a third time interval that immediately follows the second time interval, said second pulse generates a magnetic field larger than said spin-flop field with sufficient margin to write a “0” memory state in the SAF free layer in said plurality of toggle MTJ cells; and (d) reducing the second pulse to zero in a fourth time interval that immediately follows the third time interval.