Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 15: Poster:ThinFilms(1-33),Transp.(34-49),ExchBias(50-56),
Spindynamics(57-70),Micro-nanostr.Mat.(71-82),
Particles/Clust.(83-88), Mag.Imag./Surface(89-96),
Spinelectronics(97-109), Theory/Micromag.(110-116),
Spinstruct/Phasetr.(117-128),Magn.Mat.(129-139),
Aniso.+Measuring(140-145), MolMag.(146-152),
MSMA(153-156)
MA 15.98: Poster
Dienstag, 27. März 2007, 15:00–19:00, Poster A
Chemical and magnetic interface properties of tunnel junctions with Co2MnSi / Co2FeSi multilayer electrode — •Daniel Ebke1, Jan Schmalhorst1, Marc Sacher1, Ning-Ning Liu1, Andy Thomas1, Andreas Hütten1, Elke Arenholz2, and Günter Reiss1 — 1Thin Films and Nanostructures, Department of Physics, Bielefeld University, 33501 Bielefeld, Germany — 2Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
Transport as well as chemical and magnetic interface properties of two kinds of magnetic tunnel junctions (MTJs) with Co2FeSi electrode, Al-O barrier and Co-Fe counter electrode are investigated. For junctions with Co2FeSi single layer electrode a tunnel magnetoresistance of up to 52% is found for an optimal Al thickness of 1.5nm, whereas the room temperature bulk magnetization of the Co2FeSi film reaches only 75% of the expected value. By using a [Co2MnSi / Co2FeSi] multilayer electrode the magnetoresistance can be increased to 114% and the full bulk magnetization is reached. For Al thickness smaller than 1nm the TMR of both kinds of MTJs decreases rapidly to zero. On the other hand for 2 to 3nm thick Al the TMR decreases only slowly. The Al thickness dependence of the TMR is directly correlated to the element-specific magnetic moments of Fe and Co at the Co2FeSi / Al-O interface for all Al thickness. Especially, for optimal Al thickness and annealing, the interfacial Fe moment of the single layer electrode is about 20% smaller than for the multilayer electrode indicating smaller atomic disorder at the barrier interface for the latter MTJ.