Layer resolved magnetization dynamics in interlayer exchange coupled Ni81Fe19/Ru/Co90Fe10 by time resolved x-ray magnetic circular dichroism

The magnetization dynamics of each layer of interlayer exchange coupled Ni81Fe19/Ru(t)/Co90Fe10 films was investigated by time resolved x-ray magnetic circular dichroism (TR-XMCD) after pulsed excitation. The coupling was changed from ferromagnetic to antiferromagnetic by variation of the Ru thickness t. The precessional motion of the individual layers was detected separately by measuring the XMCD signal at the L-3 absorption edge of either nickel or cobalt. From the observation of two frequency components in the precession of both layers in samples with negligible interlayer exchange coupling, the presence of a different coupling mechanism was concluded. Using two different sample geometries, the influence of antiphase and in-phase excitation on the triggered dynamics was studied.