Regensburg 2013 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 8: Spin Excitations and Spin Torque

MA 8.8: Vortrag

Montag, 11. März 2013, 11:30–11:45, H23

Perpendicular anisotropy in CoFeB/MgO - based magnetic tunnel junctions — •Vladyslav Zbarsky¹, Marvin Walter¹, Maria Mansurova¹, Christian Leutenantsmeyer¹, Tim Eggebrecht¹, Karsten Rott², Günter Reiss², Rashid Gareev³, Tae Hee Kim⁴, and Markus Münzenberg¹ — ¹I. Physikalisches Institut, Universität Göttingen, — ²Physikalisches Institut, Universität Bielefeld — ³Physikalisches Institut, Universität Regensburg — ⁴Department of Physics, Ewha Womans University Korea

The reduction of the switching current density is important for spin-transfer torque based MRAM and predicted for the magnetic tunnel junctions (MTJs) with perpendicular magnetic anisotropy (PMA). The first experiments show that the thicknesses of CoFeB and MgO layers are crucial for the out-of-plane magnetic behaviour. In this context, samples with a CoFeB thickness gradient were fabricated and MOKE measurements as well as electrical characterization carried out. For CoFeB layers below 1.3 nm a perpendicular anisotropy is observed. On those samples, MTJs with 155 nm diameter show STT with a very low switching current density of 2 · 10⁵ A/cm². Samples with higher CoFeB thickness show a change of magnetic behaviour from out-of-plane to in-plane easy axis. To investigate the influence of the MgO interface, a thin Co layer is inserted at one of the MgO interfaces and its influence on the magnetic anisotropy is studied.