Berlin 2008 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 19: Spin Dynamics / Spin Torque I
MA 19.2: Vortrag
Mittwoch, 27. Februar 2008, 14:15–14:30, EB 301
Influence of Fe thickness on spin transfer torque in Fe/MgO/Fe — •Christian Heiliger1,2 and Mark D. Stiles1 — 1Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899-6202 — 2Maryland NanoCenter, University of Maryland, College Park, MD, 20742
We report calculations of the spin transfer torque in Fe/MgO/Fe tunnel junctions using a non-equilibrium Keldysh formalism implemented in the Korringa-Kohn-Rostoker Green’s function method [1]. For the coherent interfaces achievable for this lattice matched system, the Fe layers are half metallic with respect to the Δ1 states at the Brillouin zone center. This property causes the high tunnelling magnetoresistance measured in Fe/MgO/Fe tunnel junctions [2]. Our calculations show that it also leads to strong localization of the spin transfer torque to the interface. Due to the restriction of the spin transfer torque to the interface, the in-plane torque per current is independent of the Fe layer thickness for more than three monolayers of Fe. This work has been supported in part by the NIST-CNST/UMD-NanoCenter Cooperative Agreement.
[1] C. Heiliger, M. Czerner, B. Yu. Yavorsky, I. Mertig, M. D. Stiles, J. Appl. Phys. (in press); arXiv:0711.2082.
[2] C. Heiliger, P. Zahn, I. Mertig, Materials Today 9, 46 (2006).