Regensburg 2007 – scientific programme

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MA: Fachverband Magnetismus

MA 26: Exchange Bias

MA 26.7: Talk

Thursday, March 29, 2007, 16:45–17:00, H10

X-ray magnetic circular dichroism and X-ray resonant magnetic scattering investigations of IrMn/NiFe exchange bias bilayer — •Florin Radu, Shrawan Mishra, Detlef Schmitz, Enrico Schierle, Hermann Dürr, and Wolfgang Eberhardt — BESSY GmbH, Albert-Einstein Strasse 15, D-12489,

We have employed Soft X-ray Magnetic Circular Dichroism(XMCD) and Soft X-ray Resonant Magnetic Scattering (XRMS) to study the magnetic interface of an antiferromagnet/ferromagnet (AF/F) exchange bias Si(100)/SiO₂/Cu(5 nm)/Ni₈₁Fe₁₉(7.5 nm)/Ir₂₀Mn₈₀(2.5 nm)/Cu(2.5 nm) bilayer. The XMCD curves for the AF layer measured at the Mn L3 and L2 edges show a non-vanishing weak signal. In the positive magnetic saturation the Mn XMCD signal is different in magnitude and shape with respect to the one measured in the negative magnetic saturation. By comparison, the XMCD signals measured at the Ni L2 and L3 edges are equal for both magnetization orientations. This suggests that two types of uncompensated AF spins behave differently upon magnetization reversal. The frozen-in AF spins do not change sign upon magnetization reversal whereas the rotatable AF spins do follow the rotation of the F spins. Element specific reflectivity curves measured at the Mn L3 edge with circular polarized light for both helicities exhibits a deviation at the minima of the reflectivity curves. This might indicate that the uncompensated AF spins are localized at the F/AF interface. The depth profile can be retrieved after numerical analysis which is under consideration.