MAGNETIC TUNNELING IN FE-AL2O3-FE TRILAYERS WITH RADIOFREQUENCY SPUTTERED AL2O3 BARRIER LAYERS

We have prepared iron and Al2O3 thin films and Fe-Al2O3-Fe trilayers b y RF magnetron sputtering. The argon pressure during the process is fo und to have a significant influence on the microstructure and the coer civity of the Fe layers so that we could obtain Fe-Al2O3-Fe trilayers with a spin-valve-like magnetic behaviour for Al2O3 thickness as thin as 9 Angstrom. Perpendicular transport measurements of such junctions indicate tunnel behaviour with barrier heights close to 1.5 eV while t he barrier width is consistently lower than the nominal Al2O3 thicknes s. Magnetoresistance of these samples reaches up to 1.1% at room tempe rature.