Abstract: A magnetic tunnel junction (MTJ) sensor system and a method for fabricating the same are provided. First provided is an antiferromagnetic (AFM) layer. A first ferromagnetic layer with a pinned magnetization is disposed adjacent to the AFM layer for serving as a pinned layer. Next included is a tunnel barrier layer adjacent to the first ferromagnetic layer, and a second ferromagnetic layer adjacent to the tunnel barrier layer. Adjacent to the second ferromagnetic layer is a spacer. A third ferromagnetic layer is positioned adjacent to the spacer for working in conjunction with the second ferromagnetic layer to serve as a free layer. The magnetization direction of the pinned layer is substantially perpendicular to the magnetization direction of the free layer at zero applied magnetic field. A cap layer resides adjacent to the third ferromagnetic layer. A thickness of the first ferromagnetic layer and second ferromagnetic layer is selected to achieve a resonant tunneling effect.