Berlin 2008 – scientific programme

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MA: Fachverband Magnetismus

MA 8: Magnetic Imaging

MA 8.1: Talk

Monday, February 25, 2008, 15:15–15:30, H 1012

Bubble domains in [Co/Pt]/Ru multilayers — •Cristina Bran^1,2, Ulrike Wolff¹, Olav Hellwig³, Ludwig Schultz¹, and Volker Neu¹ — ¹IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden, Germany — ²IMPRS "Dynamical Processes in Atoms, Molecules and Solids", Nöthnitzer Str. 38 — ³San Jose Research Center, Hitachi Global Storage Technologies, 650 Harry Road, San Jose, CA 95120, USA

[Co/Pt]/Ru multilayers present a large variety of different magnetic domain configurations due to the competition between ferromagnetic dipolar coupling and antiferromagnetic coupling through the Ru spacer layer. In this study we focused on [(Co(4Å)/Pt(7Å))₈Co(4Å)/Ru(9Å)]₁₈ multilayers which present a predominant dipolar coupling at room temperature. We used a Digital Instruments Dimension 3100 to image the domain structure as a function of an external perpendicular field. In a zero field state, due to the perpendicular anisotropy, band domains with average domain width of 180 nm are observed. By increasing the external magnetic field the domains which are aligned parallel to the field grow, while the oppositely aligned domains shrink. This process is gradually, until the domains transform into worms and, in the end, into a bubble domain structure at 0.34 T. Theoretical calculations, previously developed for single layer film with perpendicular anisotropy [1], are in good agreement with our experimental results, revealing little influence of the antiferromagnetic coupling.

[1] A.A. Thiele, J. Appl. Phys, 41, 1139 (1970).