Comparison of the interfacial structure between MgO and Al-O oxidation layers for perpendicular magnetic tunnel junction

We discuss the interfacial structure of MgO and Al-O barrier layers and influence on the magnetic properties of perpendicular magnetic tunnel junction (pMTJ) devices. The pMTJs layer structures analyzed were Si-wafer/Pt/Gd(FeCo)/FeCo/MgO (AlO)/FeCo/Tb(FeCo)/Pt. The deposit of all pMTJs structures was carried out by rf and dc magnetron sputtering systems. Transmission electron microscopy (TEM) clearly showed that the interfacial structure of FeCo/MgO or AlO/FeCo in the pMTJs was very smooth and uniform. Hysteresis loops obtained by an alternating gradient magnetrometer (AGM) for the different oxide barrier layers of pMTJ structures showed that the Al-O layer performs better than the MgO layer. An additional discussion on the oxide layer thickness in the TEM and AGM measurements is also presented. (C) 2006 American Institute of Physics.