providing an MTJ stack, including a capping layer having a top surface, a bottom electrode, and a dielectric layer, having a top surface, that encapsulates said MTJ stack and extends above said capping layer;

etching in said dielectric layer a trench, having vertical sidewalls, that is longer and wider than said capping layer and that extends downwards as far as said capping layer top surface;

then just filling said trench with a conductive material, thereby forming a bit line that passes over said MTJ stack and that has a top surface coplanar with said dielectric top surface;

then depositing an insulating layer on said coplanar surfaces;

depositing on said insulating layer a ferromagnetic layer;

depositing an antiferromagnetic layer on said ferromagnetic layer, thereby forming a concentrator for magnetic flux that results from the passage of current through said bit line; and

annealing said ferromagnetic and antiferromagnetic layers in the presence of a magnetic field whose direction is parallel to that of said bit line thereby providing a domain stabilizing field for said ferromagnetic layer.