Dresden 2009 – scientific programme
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MA: Fachverband Magnetismus
MA 40: Poster II: Bio- and Molecular Magnetism (1-9); Magnetic Coupling Phenomena/Exchange Bias (10-15); Magnetic Particlicles and Clusters (16-29); Micro and Nanostructured Magnetic Materials (30-51); Multiferroics (52-64); Spin Injection in Heterostructures (65-67); Spin-Dyn./Spin-Torque (68-93); Spindependent Transport (94-108)
MA 40.103: Poster
Friday, March 27, 2009, 11:00–14:00, P1A
Preparation and characterization of sputtered CoFeB/MgO/CoFeB based TMR magnetic tunnel junctions (MTJs) — •Neda Sadrifar1, Senthilnathan Mohanan1, Sören Selve2, Ute Kaiser2, and Ulrich Herr1 — 1Institut für Mikro- und Nanomaterialien, Universität Ulm, 89081 Ulm — 2Materialwissenschaftliche Elektronenmikroskopie, Universität Ulm
MTJs with amorphous aluminum oxide tunnel barrier are currently used in magnetoresistive random access memory (MRAM) and the read heads of hard disk drives. MTJs with crystalline MgO tunnel barrier and body centered cubic (bcc) Fe, Co or CoFe ferromagnetic electrodes are predicted to exhibit over 1000% magnetoresistance due to coherent tunneling of fully spin polarized electrons. MTJs with MgO barrier sandwiched between CoFeB electrodes are recently developed for practical applications and found to have TMR ratios up to 500% at RT. Crystallization of amorphous CoFeB into (001)-oriented bcc structure results in a good lattice matching with (001)-oriented MgO and a very sharp and smooth interface and consequently to highly spin polarized tunneling current and high TMR effect. In this study, CoFeB/MgO/CoFeB-based MTJs were prepared by magnetron sputtering and characterized with respect to their microstructure and roughness by XRD, AFM, SEM and TEM. The main focus is on the effect of underlayers on the morphology of the MTJ stack and formation of (001)-oriented MgO and bcc-CoFeB.