Journal of Magnetism and Magnetic Materials 282 (2004) 6–10 Magnetization reversal in patterned structures using off-specular polarized neutron scattering K. Temst a, *, M.J. Van Bael a , J. Swerts a , D. Buntinx a , H. Loosvelt a , E. Popova a , C. Van Haesendonck a , H. Fritzsche b , M. Gierlings b , L.H.A. Leunissen c , R. Jonckheere c a Laboratorium voor Vaste-Stoffysica en Magnetisme, Katholieke Universiteit Leuven, Celestijnenlaan 200 D, Leuven B-3001, Belgium b Hahn-Meitner-Institut, BENSC, Glienicker Strasse 100, Berlin D-14109, Germany c IMEC vzw, Kapeldreef 75, B-3001 Leuven, Belgium Available online 28 April 2004 Abstract Polarized neutron reflectometry with neutron spin analysis is used to investigate the magnetic properties of large arrays of ferromagnetic rectangular Co bars with in-plane magnetization, as well as exchange-biased Co/CoO islands. The off-specular neutron scattering signal contains satellite peaks due to the lateral periodicity of the dot array. Using polarized neutrons, the intensity of the satellite peaks is measured as a function of an external magnetic field applied in the sample plane. Spin analysis of the scattered neutrons reveals the magnetization reversal and saturation within the bars. r 2004 Elsevier B.V. All rights reserved. Keywords: Neutron reflection—polarized; Thin films—ferromagnetic; Magnetization—reversal The steady advance in lithography and deposi- tion techniques has created opportunities for the production of well-defined micron and nanometer- sized magnetic structures. From a scientific point of view, the motivation is two-fold: first, new physical effects are encountered when the meso- scopic regime is explored in which the size of the magnetic structures becomes of the same order of magnitude as some relevant physical length scale or when the magnetic entities interact with each other, with a semiconducting layer or a super- conducting layer. The second main reason is that the better understanding of the physics governing these mesoscopic structures can be used in large- scale industrial applications like, e.g., magnetic storage media, computer memories, and sensors. The most common experimental tools which are used in the study of patterned magnetic structures are magnetization measurements, magnetoresis- tance, and imaging methods like magneto-optical Kerr microscopy or magnetic force microscopy (MFM). MFM has been particularly useful to study the transition from single domain to multi- ple domain configuration in patterned Co struc- tures with a varying length-to-width ratio (the ARTICLE IN PRESS *Corresponding author. Tel.: +32-16-32-76-20; fax: +32-16- 32-79-83. E-mail address: kristiaan.temst@fys.kuleuven.ac.be (K. Temst). 0304-8853/$ - see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jmmm.2004.04.002