230% room temperature magnetoresistance in CoFeB/MgO/CoFeB magnetic tunnel junctions

The magnetoresistance ratio of 230% at room temperature is reported. This was achieved in spin-valve type magnetic tunnel junctions using MgO barrier layer and amorphous CoFeB ferromagnetic electrodes fabricated on thermally oxidized Si substrates. The amorphous CoFeB electrodes are of great advantage to the polycrystalline FeCo electrodes in achieving a high homogeneity in small 100 nm-sized MTJs.