Tunnel junctions with yttrium oxide barrier and various ferromagnetic electrodes

This work concerns tunnel junctions with yttrium oxide barrier prepared by plasma oxidation of a 1.5-nm Y film. The magnetoresistive properties of the junctions were studied as a function of the ferromagnetic (FM) electrodes in contact with the barrier, such as CoFe, Py (permalloy), and CoFeNiSiB. The maximum measured tunnel magnetoresistance (TMR) effect was 25% at room temperature -raised to over 40% at 5 K. The TMR and the tunnel barrier characteristics (thickness, height, and asymmetry) depend significantly on the FM electrodes and the annealing temperature. Barrier heights of less than 1 eV have been extracted in all cases -two to three times lower than the ones reported for AlO/sub x/-based junctions.