Transport properties of magnetic tunnel junctions with ion irradiated AlO barriers

The transport properties of magnetic tunnel junctions (Co - Fe/AlOx /Ni - Fe) with barriers irradiated by low energy Ar+ ions immediately after plasma oxidation of the aluminium film are investigated. The tunneling magnetoresistance is strongly reduced with increasing ion energies, whereas the area resistance product increases up to a factor 40 for ion energy up to 150 eV. At higher ion energy the resistance breaks down rapidly and the tunneling magnetoresistance vanishes completely. Structural alterations in the barrier are discussed. (C) 2003 Elsevier B. V. All rights reserved.