Patent ID: 8027129

Claim:
A product that is capable of being transformed into a magnetoresistive (MR) device with sense current confinement, the product comprising: a current perpendicular to plane (CPP) magnetoresistive (MR) stack formed by a plurality of layers including at least one magnetic free layer; and a layer of high resistivity material within the CPP MR stack, the layer of high resistivity material including a precursor that defines a region of the high resistivity material having a lower dielectric breakdown voltage than high resistivity material surrounding the region, wherein when a punch current is applied at the precursor, dielectric breakdown of the high resistivity material in the region defined by the precursor creates a conductive nanoconstriction within the layer of high resistivity material that provides a current confining path through the layer of high resistivity material for sense current flowing through the CPP MR stack in a direction perpendicular to planes of the layers forming the CPP MR stack.