Tunneling magnetoresistance in (001)-oriented FeCo∕MgO∕FeCo magnetic tunneling junctions grown by sputtering deposition

Magnetic tunneling junctions (MTJs) with MgO tunnel barrier have been fabricated on both oriented and nonoriented buffer layers on Si(001) substrate by magnetron sputtering. FeCo∕MgO∕FeCo MTJs fabricated on oriented buffer layers show larger tunneling magnetoresistance (TMR) value up to 84% without high temperature postannealing, whereas those MTJs on nonoriented buffer layers show 45% of TMR. The high-resolution transmission electron microscopy images reveal an excellent morphology and very coherent crystal structure with FeCo(001)[110]∕MgO(001)[100]∕FeCo(001)[110] orientation. The results indicate that high TMR can be achieved without high temperature postannealing by sputtering deposition on appropriate oriented buffer layers.