The magnetic head of the present invention includes a magnetoresistive read head element in which a magnetic bias layer is deposited across the surface of the wafer above the free magnetic layer. Central portions of the biasing layer that correspond to the read head track width are oxidized to essentially remove the magnetic moment of the bias layer material in those central locations. An oxygen diffusion barrier layer is then deposited upon the oxidized central portions of the biasing layer to prevent diffusion or migration of oxygen from the oxidized central regions of the biasing layer. An insulation layer, a second magnetic shield layer and further structures of the magnetic head are subsequently fabricated.