Magnetic properties of MgO-based RE-TM perpendicular magnetic tunnel junctions

Abstract We fabricated a series of perpendicularly magnetic tunnel junctions (pMTJs) of the structures Si/Ti/GdCoFe/Mg(0 or 0.4 nm)/MgO(x)/Mg(0 or 0.4 nm)/TbCoFe/Ti with various MgO barrier thicknesses. The effect of inserting Mg layers was investigated through high resolution transmission electron microscopy and hysteresis loop measurement. Experimental results show that for the case of thinner MgO barrier (1.0 nm) the insertion of Mg layers on both sides can help crystallization of MgO. For thicker MgO layer (2.0 nm) the interfaces were improved with the Mg insertion and led to the increase of coercivity and loop squareness. The results of annealing treatment show that the insertion of Mg layers can assist the junctions in keeping perpendicular anisotropy at higher annealing temperature.