Three-dimensional magnetic random access memory with high speed writing

A method of writing to a magnetic random access memory comprising:

• providing a transistor disposed on a substrate and comprising a gate width, a word line electrically coupled to the transistor, a plurality of memory layers disposed above the substrate, each memory layer comprising a plurality of magnetoresistive elements, each magnetoresistive element comprising an element width, a pinned layer comprising a fixed magnetization direction directed perpendicular to the substrate, a free layer comprising a reversible magnetization direction directed perpendicular to the substrate in its equilibrium state, and a tunnel barrier layer residing between the pinned and free layers;
• a plurality of conductor layers, each conductor layer comprising a plurality of parallel bit lines overlapping the word line, adjacent conductor layers are spaced from each other by a memory layer, the plurality of magnetoresistive elements independently electrically coupled to the plurality of bit lines at first terminals and jointly electrically coupled to the transistor at second terminals, wherein the gate width is substantially larger than the element width;
• driving a bias current pulse through a bit line in a proximity to but not through a magnetoresistive element and producing a bias magnetic field along a hard magnetic axis of the free layer;
• driving a spin-polarized current pulse through the magnetoresistive element along an easy axis of the free layer and producing a spin momentum transfer;
• whereby the magnetization direction in the free layer is reversed by a joint effect of the substantially superimposed pulses of the bias and spin-polarized currents.