Berlin 2008 – scientific programme

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MA: Fachverband Magnetismus

MA 32: Postersession II: Spinstruct./Phase Trans. (1-10); Spinelectronics (11-15); Thin Films (16 - 36); Particles/Clusters (37-45); Multiferroics (46-54); Spindynamics/Spin Torque (55 - 76); Post Deadlines (77-79)

MA 32.18: Poster

Friday, February 29, 2008, 11:15–14:00, Poster E

Modulated magnetization depth profile in dipolarly coupled Co₈₀Fe₂₀/Al₂O₃ multilayers — •Subhankar Bedanta¹, Emmanuel Kentzinger², Oleg Petracic^1,3, Jan Rhensius¹, Wolfgang Kleemann¹, Theo Kleinefeld¹, Amitesh Paul², Thomas Brückel², Ulrich Rücker², Susana Cardoso⁴, and Paulo Freitas⁴ — ¹Angewandte Physik, Universität Duisburg-Essen, Germany — ²Institut für Festkörperforschung, Forschungszentrum Jülich, Germany — ³Institut für Experimentalphysik IV, Ruhr-Universität Bochum, Germany — ⁴INESC, Rua Alves Redol 9-1, Lisbon, Portugal

Polarized neutron reflectivity (PNR), magnetometry, and magneto-optic Kerr microscopy studies have been performed on two metal-insulator multilayers (MIMs) [Co₈₀Fe₂₀(t_n)/Al₂O₃(3nm)]₉ with t_n = 1.6 and 1.8 nm. MIMs exhibit dominant dipolar coupling between the ferromagnetic CoFe layers. Our PNR measurements at the coercive field reveal a novel and unexpected magnetization state of the sample exhibiting an oscillating magnetization depth profile from CoFe layer to layer with a periodicity of five and eight bilayers along the multilayer stack for the t_n = 1.6 and 1.8 nm samples, respectively [1]. Domain imaging by Kerr microscopy reveals different grey scales which evidence the heterogeneity of layer-by-layer magnetization in the multilayer stack [2]. With the help of micromagnetic simulations we demonstrate that competition between long and short-ranged dipolar interactions apparently gives rise to this unusual phenomenon [1].
S. Bedanta et al., Phys. Rev. B 74, 054426 (2006).
S. Bedanta et al., Physica B 397, 65 (2007).