Dresden 2006 – scientific programme
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MA: Magnetismus
MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)
MA 20.66: Poster
Tuesday, March 28, 2006, 15:15–19:15, P1
In-situ MFM study of the magnetization process in AF coupled CoPt/Ru multilayers — •Ulrike Wolff1, Tetyana Shapoval1, Ulrich Rößler1, Ludwig Schultz1, Olav Hellwig2, and Volker Neu1 — 1IFW Dresden, Helmholtzstr. 20, D-01069 Dresden, Germany — 2Hitachi GST, San Jose, CA
CoPt/Ru multilayers exhibit a broad range of fascinating magnetic structures due to the competing energy terms of antiferromagnetic exchange coupling through the Ru spacer, dipolar stray field interactions and magnetostatic Zeeman terms in an external magnetic field. In zero field, two distinctly different magnetic states are observed depending on temperature and magnetic history, but possess vanishing remanence and are therefore best studied by direct imaging of the domain structure. This paper presents a study of magnetization processes of a CoPt/Ru sample directly observed in a Low Temperature Magnetic Force Microscope at different temperatures and magnetic fields. After saturation at 300 K in a field of 0.5 T the zero field state resembles typical stripe domains observed for films with perpendicular magnetic anisotropy. This state is explained by an effectively ferromagnetic dipolar coupling through the Ru layer. Saturating in a field of 0.6 T at 10 K brings the sample into a completely compensated, which can be understood by the AF coupling through the Ru layer. The cross-over temperature Tx for these two different ZF states is found to be 270 K.