Multi-state magnetoresistance random access cell with improved memory storage density

A method of storing multiple states in a multi-state magnetoresistive random access memory device comprising the steps of:

• providing a multi-state magnetoresistive random access memory (MRAM) cell adjacent to a first conductor and a second conductor wherein the MRAM cell includes a first region and a second region separated by a non-ferromagnetic spacer layer, wherein the first region is adjacent the non-ferromagnetic spacer layer and includes a first ferromagnetic layer having a free magnetic moment vector, and wherein the first region has a shape anisotropy that provides the free magnetic moment vector with four stable positions with which the free magnetic moment vector is aligned while writing the MRAM cell, and wherein each of the four stable positions corresponds to one of four resistance values which may be measured while reading the MRAM cell, and wherein the second region has a fixed magnetic moment vector that is oriented in a preferred direction both with and without an applied magnetic field, and wherein a first two stable positions of the four stable positions are oriented 180 degrees apart relative to each other along a first easy axis, and a second two stable positions of the four stable positions are oriented 180 degrees apart relative to each other along a second easy axis, wherein the first easy axis and the second easy axis are at nonzero angles relative to the preferred direction of the fixed magnetic moment vector;
• applying a first current pulse and a second current pulse in the first conductor and the second conductor, respectively, to orient the free magnetic moment vector in one of the more than two stable positions;
• and
• turning off the first current pulse and the second current pulse so that the free magnetic moment vector is aligned with one of the more than two stable positions, in the absence of an applied magnetic field.