Nanofabrication of magnetic tunnel junctions by using side-edge thin film deposition

Nanostructured double ferromagnetic tunnel junctions (MTJs) are indispensable for investigation of spin-dependent single-electron transport at low temperature. A new fabrication process that enables us to reduce the size of MTJs down to nanometer scale by using the side edge of a patterned film were developed. The multilayers of MTJ partially replaced by thick Al₂O₃/Cu double layer were prepared by using electron beam lithography and lift-off, then Pt film was vacuum-evaporated onto the side edge of Al₂O₃/Cu film, which masked MTJ during following Ar ion milling. As a result, the double MTJs with the dimension of 10 nm £ 10 mm were formed beneath the Pt film. The large tunnel magnetoresistive ratio of 35% and symmetrical I–V characteristics were obtained at room temperature.