Magnetoresistive structures and fabrication methods

A magnetoresistive structure, comprising:

• a first ferromagnetic layer having a pinned first magnetization direction set by exchange coupling;
• a spacer layer;
• and
• a second ferromagnetic layer having a single free second magnetization direction substantially perpendicular to the first magnetization direction, wherein the spacer layer interposes the first ferromagnetic layer and the second ferromagnetic layer;
• and
• a third ferromagnetic layer having a pinned third magnetization direction set by exchange coupling, wherein the third magnetization direction is substantially parallel to the first magnetization direction;
• and
• an insulating layer between the second ferromagnetic layer and the third ferromagnetic layer sufficient to set the free second magnetization direction perpendicular to the first direction in the absence of an external magnetic field.

A magnetoresistive structure, comprising:

• a first antiferromagnetic layer;
• a pinned layer comprising a first ferromagnetic layer having a pinned first magnetization direction set by exchange coupling with the first antiferromagnetic layer;
• a spacer layer;
• a free layer comprising a second ferromagnetic layer and a third ferromagnetic layer, wherein the free layer further comprises an insulating layer between the second ferromagnetic layer and the third ferromagnetic layer;
• and
• a second antiferromagnetic layer,
• wherein the spacer layer interposes the free layer and the pinned layer,
• wherein the second ferromagnetic layer has a single free second magnetization direction substantially perpendicular to the first magnetization direction,
• wherein the third ferromagnetic layer has a pinned third magnetization direction set by exchange coupling with the second antiferromagnetic layer, and
• wherein the first and second antiferromagnetic layers have substantially equal blocking temperatures.