Dresden 2006 – scientific programme
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MA: Magnetismus
MA 36: Magnetic Coupling Phenomena / Exchange-Bias
MA 36.6: Talk
Friday, March 31, 2006, 12:00–12:15, HSZ 401
Neutron reflectivity studies on lattice-matched, ordered FePt3 based antiferromagnetic/ferromagnetic films — •Dieter Lott1, P. Mani2, G. Mankey2, F. Klose3, M. Wolf4, and A. Schreyer1 — 1GKSS research center, Geesthacht, Germany — 2MINT Center, The University of Alabama, Tuscaloosa, AL, USA — 3Spallation Neutron Source, Oak Ridge National Laboratory,Oak Ridge, TN, USA — 4ILL, Grenoble, France
Lattice-matched antiferromagnetic(AF)/ferromagnetic(F) films offer an ideal layered system to study exchange bias. Epitaxial films of FePt3 exhibit an AF ordering with a spin wave vector QA = (1/2, 1/2, 0) and a Néel temperature of TN=160 K. CoPt3 is chosen as the ferromagnet since it has the same L12 crystal structure as FePt3 and nearly the same lattice constant, and it can be grown with an in-plane easy axis. X-ray diffraction shows that the peak widths of the rocking curves for FePt3 films grown on Al2O3 and MgO are very different indicating that the samples grown on Al2O3 have larger grains and a smaller mosaic spread. On the other side, results from vibration sample magnetometry reveal that only the sample grown on MgO shows a significant exchange bias effect. AF films with fewer defects and strain-free interfaces yield a lower exchange bias. Polarized neutron reflectivity was carried on a CoPt3/FePt3 multilayer grown on MgO to probe the layer-specific magnetizations owing to the significant difference in the neutron scattering length density between Fe and Co and elucidate the magnetic switching behavior in this system for different temperatures and magnetic fields.