Dependence of tunneling magnetoresistance on CoFe interfacial layer thickness in NiFe/Al2O3/NiFe tunnel junctions

Magnetic tunnel junctions of Ta/Ni-81/Fe-19/Fe50Mn50/Ni81Fe19/Co50Fe50/Al2O3/Co50Fe50/Ni81Fe19 were fabricated by a magnetron sputtering system. We have studied the change of tunneling magnetoresistance(MR) ratio and junction resistance as a function of CoFe interfacial layer thickness. The MR ratio rapidly increased and slowly decreased as the CoFe layer thickness increased. The junction resistance increased with the introduction of CoFe layer. The increase is due to more uniform Al layer formation on a CoFe layer than a NiFe layer.