Dresden 2014 – scientific programme
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MA: Fachverband Magnetismus
MA 55: Poster II
MA 55.21: Poster
Friday, April 4, 2014, 10:30–13:30, P2
Temperature dependent sign change in tunnel magnetoresistance of magnetic tunnel junctions with one magnetite electrode — •Luca Marnitz1, Karsten Rott1, Stefan Niehörster1, Christoph Klewe1, Daniel Meier1, Matthäus Witziok2, Andreas Krampf2, Olga Schuckmann2, Tobias Schemme2, Karsten Kuepper2, Joachim Wollschläger2, Günter Reiss1, and Timo Kuschel1 — 1Bielefeld University, Germany — 2Osnabrück University, Germany
Due to its high spin polarization and Curie temperature, magnetite (Fe3O4) is a promising material for room temperature applications in spintronics. Despite these promising features, MTJs using magnetite have not yet shown a large TMR value, the largest being -27% in CoFe/Al2O3/MgO/Fe3O4/Al2O3 (001) junctions[1]. Magnetite grown on MgO shows signs of an interdiffusion of Mg from the substrate through the magnetite at temperatures between 250 and 350∘C[2].
We have studied this effect by annealing CoFeB/MgO/Fe3O4/MgO (001) MTJs at different temperatures and observed a sign change from a negative TMR to a positive TMR. Additionally, MTJs with magnetite thin films treated by Ar etching showed a vastly increased TMR value of up to -12% for an annealing temperature of 230∘C from a starting value of about -1%. A good foundation for further research is provided, including MTJs with two magnetite electrodes with an additional NiO pinning layer and different barrier materials.
[1] T. Kado, Appl. Phys. Lett. 92, 092502 (2008)
[2] Y. Gao et al., J. Mater. Res. 13, 2003 (1998)