Title :
Tunnel junctions with yttrium oxide barrier and various ferromagnetic electrodes
Author :
Dimopoulos, Theodoros ; Gieres, Günter ; Colis, Silviu ; Lopez, Ricardo ; Vieth, Michael ; Wecker, Joachim ; Luo, Yuansu ; Samwer, Konrad
Author_Institution :
CT-MM1, Siemens AG, Erlangen, Germany
fDate :
7/1/2004 12:00:00 AM
Abstract :
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 AlOx-based junctions.
Keywords :
Permalloy; chemical interdiffusion; cobalt alloys; diffusion barriers; electrodes; ferromagnetic materials; magnetic tunnelling; oxidation; tunnelling magnetoresistance; yttrium compounds; 1.5 nm; AlO-based junctions; FM electrodes; YO-CoFe; YO-CoFeNiSiB; annealing temperature; asymmetry characteristics; barrier heights; ferromagnetic electrodes; height characteristics; magnetic memories; magnetic sensors; magnetic thin-film devices; magnetic tunneling; magnetoresistive properties; plasma oxidation; thickness characteristics; tunnel barrier characteristics; tunnel junctions; tunnel magnetoresistance effect; yttrium oxide barrier; Electrodes; Magnetic properties; Oxidation; Plasma measurements; Plasma properties; Plasma temperature; Temperature dependence; Thickness measurement; Tunneling magnetoresistance; Yttrium; Magnetic memories; magnetic sensors; magnetic thin-film devices; tunneling;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2004.829282
