Influence of noble-gas ion irradiation on alumina barrier of magnetic tunnel junctions

Sacher M, Sauerwald J, Schmalhorst J-M, Reiss G. Influence of noble-gas ion irradiation on alumina barrier of magnetic tunnel junctions. JOURNAL OF APPLIED PHYSICS. 2005;98(10): 103532.The transport properties of Co/Al2O3/Co magnetic tunnel junctions with ion-irradiated tunneling barrier are reported. The irradiation by He+ and Ar+ with energies ranging from 15 to 105 eV takes place in situ after oxidation of the 1.4-nm-thick Al layer. For both ion species the area resistance of the junctions increases strongly with ion energy, simultaneously the tunneling magnetoresistance is reduced. But the energy dependence of both properties is different for He+ and Ar+ irradiations. Additionally the bias voltage dependence of the tunneling magnetoresistance is deteriorated with increasing ion energy especially for Ar+ irradiation. These experimental results are discussed with respect to the energy-dependent penetration depth of He+ and Ar+ and their energy loss in the barrier. (c) 2005 American Institute of Physics