Dresden 2014 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 10: Spin-dependent Transport Phenomena

MA 10.5: Vortrag

Montag, 31. März 2014, 16:00–16:15, HSZ 403

Perpendicular magnetic tunnel junctions with Mn_3−xGa bottom electrode — •Manuel Glas¹, Daniel Ebke², Eugen Schellenberg¹, Karsten Rott¹, Jan Schmalhorst¹, and Günter Reiss¹ — ¹Thin Films and Physics of Nanostructures, Bielefeld University, Germany — ²Max Planck Institute for Chemical Physics of Solids, Dresden, Germany

The integration of Mn_3−xGa thin films with perpendicular magnetic anisotropy into magnetic tunnel junctions was investigated. MgO (001) and SrTiO₃ (001) substrates were used to achieve epitaxial (001)-oriented thin films. Crystallographic and magnetic measurements were performed to characterise the Mn_3−xGa electrodes. To overcome the lattice mismatch between the bottom electrode and the MgO barrier, a thin CoFeB interlayer was deposited. A magnetically perpendicular counter electrode was formed by Co/Pt multilayers. To improve the applicability, we replaced the Co/Pt multilayer by a perpendicularly magnetised CoFeB thin film. Additionally, CoFeB based perpendicular magnetic tunnel junction were investigated for comparison. Samples with Co/Pt counter electrode exhibited a TMR effect of only 3 % and samples with CoFeB top electrode showed an effect of 5 %. However, CoFeB based tunnel junctions revealed the highest MR effect with 72 %. The temperature dependent transport measurements of Mn-Ga based tunnel junctions with CoFeB counter electrode exhibited an initial increase of the TMR effect and a maximum effect between 80 and 100 K. For lower temperatures the TMR effect decreases, due to a reversal of the coercivity of both CoFeB electrodes.