MTJ elements with MgO barrier using RE-TM amorphous layers for perpendicular MRAM

Magnetic properties of an FeCo/TbFeCo bilayer were investigated by MFM and the anomalous Hall effect. In the case of FeCo(x nm)/TbFeCo(50 nm), FeCo as thin as 2 nm behave as perpendicular magnetization film while large thickness of RE-TM films, such as TbFeCo(100nm) causes the increase of the critical thickness up to 4 nm. The prototype of perpendicular MTJ, p-MTJ, consist of TbFeCo/Fe/MgO/Fe/GdFeCo exhibited high squareness raito of 0.8 having low coercivity of 117 Oe while MgO(100) texture was confirmed in the Fe/MgO/Fe junction prepared on the amorphous GdFeCo layer even though the thickness of MgO is as thin as 3 nm.