A magnetic random access memory device including a pinned layer having a diffusion barrier, a sense layer, and a tunnel barrier to electrically couple the pinned layer to the sense layer. A method for forming a magnetic random access memory device including forming, on a substrate, a sense layer, forming a tunnel barrier on the sense layer, forming a pinned layer on the tunnel barrier, where the pinned layer includes a diffusion barrier to stop manganese atoms from diffusing to the interface of the tunnel barrier, and annealing the substrate, the sense layer, the tunnel barrier and the pinned layer. The diffusion barrier can include a native oxide having a thickness up to about seven angstroms or an aluminum oxide having a thickness up to about seven angstroms.