Regensburg 2013 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 8: Spin Excitations and Spin Torque

MA 8.9: Vortrag

Montag, 11. März 2013, 11:45–12:00, H23

Fabrication of CoFeB|MgO|CoFeB magnetic tunneljunctions with ultrathin barriers for thermal spin transfer torque — •Johannes Christian Leutenantsmeyer¹, Marvin Walter¹, Vladyslav Zbarsky¹, Patrick Peretzki², Henning Schuhmann², Michael Seibt², Karsten Rott³, Günter Reiss³, Andy Thomas³, and Markus Münzenberg¹ — ¹I. Phys. Inst., Universität Göttingen — ²IV. Phys. Inst., Universität Göttingen — ³Thin Films and Physics of Nanostructures, Universität Bielefeld

Thermal spin-transfer torque (T-STT) describes the combination of the spin-transfer torque effect with the spin-caloric magneto-Seebeck effect. Here, thermally excited electrons are used to manipulate the magnetization of a magnetic tunneljunction (MTJ). Calculations have been performed in 2011 [1] suggesting a switching T-STT at temperature gradients in the order of 10 K in MTJs with 3 monolayer (ML) MgO barriers. The effect is suitable for storage application, enhancing the energy efficiency of those devices.

We have fabricated CoFeB/MgO MTJs with 3 ML MgO barriers and reasonable interface roughness. For different deposition parameters (in particular MgO growth temperature), the quality of the interface was studied via quantitave HR-TEM analysis. Characterization shows a TMR-effect of up to 55% in nanoscaled junctions. Also spin-transfer torque was observed in 4 ML junctions. MTJs with 4 ML MgO and perpendicular magnetization anisotropy (PMA) show ultra low switching currents (0.2 MA/cm²), making PMA MTJs suitable for T-STT.

[1] Jia et al., PRL 107 176603, 2011