Synthetic-ferrimagnet sense-layer for high density MRAM applications

A sense layer for a magnetic memory element, said sense layer comprising:

• a first magnetizable layer having a first material composition, a thickness t1 and a magnetic moment oriented in a first direction;
• a second magnetizable layer over said first magnetizable layer, said second magnetizable layer having said first material composition and a thickness greater than t1 and a magnetic moment oriented in a second direction opposite said first direction;
• a conductive spacer layer formed between said first and second magnetizable layers;
• said first and second magnetizable layers and conductive spacer layer being formed to provide stray field coupling between said first and second layers such that said first and second layers having magnetic moments oriented anti-parallel to each other;
• and
• said first and second magnetizable layers and conductive spacer layer each being formed of a material and thickness sufficient to provide antiferromagnetic exchange coupling having a value greater than 0 and <=200 Oe between the first and second layers across said spacer layer, the magnetic orientation of said first and second layers rotating substantially simultaneously in the presence of an applied magnetic field.

A magnetic memory structure comprising:

• a sense layer comprising:
• a first magnetizable layer with a magnetic moment oriented in a first direction;
• a second magnetizable layer with a magnetic moment oriented in a second direction opposite to said first layer;
• a spacer layer formed between said first and second magnetizable layers;
• said layers being formed of a material and thickness sufficient to provide stray field coupling between said first and second magnetizable layers such that said first and second magnetizable layers have magnetic moments oriented anti-parallel to each other;
• said layers being formed of a material and thickness sufficient to provide antiferromagnetic exchange coupling between the first and second layers such that the magnetic moments of the first and second layers are free to rotate substantially simultaneously in the presence of an applied magnetic field so that the first and second magnetic moments of the magnetizable layers can be oriented in the other of said first and second directions;
• a pinned layer;
• and
• a tunneling barrier formed from a non-magnetic material provided between said sense layer and said pinned layer.

An array of magnetic memory elements comprising:

• a substrate;
• a first set of substantially parallel electrically conductive lines formed on the substrate;
• a second set of substantially parallel electrically conductive lines formed on the substrate substantially orthogonal to the first set of conductive lines and which intersect with the first set of conductive lines;
• a plurality of magnetic memory elements, each said each element formed between and coupled to the first and second conductive line intersection points, said elements comprising a magnetic memory sense layer comprising:
• a first magnetizable layer with a magnetic moment oriented in a first direction;
• a second magnetizable layer with a magnetic moment oriented in a second direction opposite to said first direction;
• a spacer layer formed between said first and second magnetizable layers;
• said layers being formed of a material and thickness sufficient to provide stray field coupling between said first and second layers across said spacer layer such that said first and second layers have magnetic moments oriented antiparallel to each other;
• and
• said layers being formed of a material and thickness sufficient to provide antiferromagnetic exchange coupling between the first and second layers across said spacer layer such that the magnetic moments of the first and second layers are free to rotate substantially simultaneously in the presence of an applied magnetic field so that the first and second magnetic moments of the magnetizable layers can be oriented in the other of said first and second directions.

A computer system comprising:

• a processor;
• a magnetic memory device electrically coupled to the processor, said memory device comprising:
• a first magnetizable layer with a magnetic moment oriented in a first direction;
• a second magnetizable layer with a magnetic moment oriented in a second direction opposite to said first direction;
• a spacer layer formed between a first and second magnetizable layers;
• said layers being formed of a material and thickness sufficient to provide stray field coupling between said first and second layers such that said first and second layers have magnetic moments oriented antiparallel to each other;
• and
• said layers being formed of a material and thickness sufficient to provide antiferromagnetic exchange coupling between the first and second layers such that the magnetic moments of the first and second layers are free to rotate substantially simultaneously in the presence of an applied magnetic field so that the first and second magnetic moments of the magnetizable layers can be oriented in the other of said first and second directions.

A magnetic memory structure comprising:

• a sense layer comprising:
• a first magnetizable layer with a magnetic moment oriented in a first direction;
• a second magnetizable layer with a magnetic moment oriented in a second direction opposite to said first layer;
• a spacer layer formed between said first and second magnetizable layers;
• said layers being formed of a material and thickness sufficient to provide stray field coupling between said first and second magnetizable layers such that said first and second magnetizable layers have magnetic moments oriented anti-parallel to each other;
• said layers being formed of a material and thickness sufficient to provide antiferromagnetic exchange coupling between the first and second layers such that the magnetic moments of the first and second layers are free to rotate substantially simultaneously in the presence of an applied magnetic field so that the first and second magnetic moments of the magnetizable layers can be oriented in the other of said first and second directions;
• a pinned layer;
• and
• a conductive layer provided between said sense layer and said pinned layer.

A method for manufacturing a magnetic memory element comprising:

• forming a pinned or reference layer with a magnetization in a first direction over a substrate;
• forming a tunnel barrier layer over the pinned layer;
• and
• forming a sense layer over the tunnel barrier layer, said sense layer having a first and second ferromagnetic layer separated by a spacer layer and a characteristic which results in stray field coupling and antiferromagnetic exchange coupling between said first and second ferromagnetic layers.

A method for manufacturing a magnetic memory element comprising:

• forming a sense layer over a substrate, said sense layer having a first and second ferromagnetic layer separated by a spacer layer and a characteristic which results in stray field coupling and antiferromagnetic exchange coupling between said first and second ferromagnetic layers across said spacer layer;
• forming a tunnel barrier layer over the sense layer;
• and
• forming a pinned or reference layer with a magnetization in a first direction over a said tunnel barrier.

A method for manufacturing a magnetic memory element comprising:

• forming a pinned or reference layer with a magnetization in a first direction over a substrate;
• smoothing a surface of the pinned layer;
• forming a tunnel barrier layer over the pinned layer;
• and
• forming a sense layer over the tunnel barrier layer, said act of forming said sense layer comprising:
• forming said first magnetization layer over the tunnel barrier layer;
• smoothing the first magnetization layer;
• forming a spacer layer over the first magnetization layer;
• forming a second magnetization layer over of the spacer layer;
• said first and second magnetization layers and spacer layer being formed such that said layers are stray field coupled and antiferromagnetic exchange coupled across said spacer layer;
• said first and second magnetizable layer are formed having a magnetic saturation times said first layer's thickness which is not equal to said second layer's magnetic saturation times second layer thickness of the second magnetizable layer.

A method for manufacturing a magnetic memory element comprising:

• forming a pinned or reference layer with a magnetization in a first direction over a substrate;
• forming a conductive layer over the pinned layer for creating a giant magnetoresistance effect;
• and
• forming a sense layer over the tunnel barrier layer, said sense layer having a first and second ferromagnetic layer separated by a spacer layer and a characteristic which results in stray field coupling and antiferromagnetic exchange coupling between said first and second ferromagnetic layers.