Regensburg 2007 – scientific programme

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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 15.107: Poster

Tuesday, March 27, 2007, 15:00–19:00, Poster A

Chemical and magnetic interface properties of Co-Fe-B / MgO / Co-Fe-B tunnel junctions — •Jan Schmalhorst¹, Xinli Kou^1,2, Andy Thomas¹, Elke Arenholz³, and Günter Reiss¹ — ¹Thin Films and Nanostructures, Department of Physics, Bielefeld University, 33501 Bielefeld, Germany — ²Lanzhou University, 222 South Tianshui Road, Lanzhou 7300000, China — ³Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA

The chemical and magnetic properties at the lower Co-Fe-B / MgO interface of Co-Fe-B /MgO / Co-Fe-B magnetic tunnel junctions is investigated by X-ray absorption spectroscopy and X-ray magnetic circular dichroism. The influence of the annealing temperature and of a thin (0.5nm or 0.75nm) metallic Mg interlayer between the lower electrode and the RF-sputter deposited MgO barrier is studied. The room temperature tunnel magnetoresistance increases strongly with annealing temperature for both Mg interlayer thicknesses. Starting at 20% after annealing at 200°C it reaches a maximum value of 112% after annealing at 350°C. The annealing temperature dependent influence of the thermally induced reduction of interfacial Fe-O, the simultaneous increase of the Fe magnetic moment and the boron concentration in the electrode and in the Mg-O barrier on the TMR amplitude will be discussed.