Pulsed inductive microwave magnetometer ͑PIMM͒, conventional ferromagnetic resonance ͑FMR͒, and vector network analyzer FMR ͑VNA-FMR͒ have been used for complementary studies of the various excited modes in exchange-coupled NiFe͑30 nm͒ /Ru͑d Ru ͒ / NiFe͑30 nm͒ films with variable Ru thicknesses d Ru . For antiferromagnetically coupled layers, two modes, which vary in their relative intensity as a function of the bias field, are detected. These two modes, which are observable simultaneously over a limited range of the bias field with PIMM, are identified as optic and acoustic modes. The mode frequencies and the interlayer exchange coupling are found to oscillate as a function of the Ru layer thickness with a period of 8.5 Å. The frequency oscillations of the optic mode are coupling dependent, while those of the acoustic mode are indirectly related to coupling via the canting angle of the layer magnetizations below the saturation. Comparison between PIMM and VNA-FMR in terms of frequency of modes shows good agreement, but the optic mode is observed over a wider field range with VNA-FMR. Furthermore, we clearly observed different behaviors of the FMR linewidths as a function of the spacer thickness for the optic and acoustic modes. In addition, perpendicular standing spin waves have been studied as a function of coupling. The FMR linewidth of the different modes increases with the microwave frequency and typical damping constants of ␣ = 0.0073 have been measured. The effect of the pulse field amplitudes on the properties of the various excited modes has been simulated and studied experimentally.

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1 -Oxygenated carbazoles are prepared in 4 steps from indole-2-carboxylates by condensation with y-butyrolactones to give the lactones (1 2), followed by hydrolysis with concomitant decarboxylation to the alcohols (13), and oxidation to the aldehydes (14). The aldehydes ( 14) cyclise to l-methoxycarbazoles on treatment with boron trifluoride-methanol or with methanolic hydrogen chloride. The methoxycarbazoles (1 5a) and (4) were converted into the corresponding carbazolequinones (1 8) and ( 7) by demethylation, and oxidation. The carbazole alkaloids murrayafoline-A (4) and murrayaquinone-A (7) were prepared.

The magnetization dynamics of each layer of interlayer exchange coupled Ni 81 Fe 19 / Ru͑t͒ / Co 90 Fe 10 films was investigated by time resolved x-ray magnetic circular dichroism ͑TR-XMCD͒ 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.

Vector network analyzer ferromagnetic resonance spectroscopy (VNA-FMR) is used here to study the different excited modes of sputtered asymmetrical NiFe(13.6 nm)/Ru(d Ru )/ NiFe(27.2 nm) exchange-coupled films with variable Ru thicknesses. The obtained results have been compared to those of the symmetrical NiFe(30 nm)/Ru(d Ru )/NiFe(30 nm). In both cases, the measurements show the existence of an optic and an acoustic precessional mode. The optic mode was only observed over limited field ranges, especially in the symmetrical trilayers. To overcome such a limitation, we developed a new technique similar to the longitudinal FMR, where the bias and the rf field are parallel to each other and perpendicular to the pinning field. Interestingly, and in contrast to the symmetrical trilayers, we observed a mode anti-crossing in the dispersion relation of the asymmetrical layers that we attributed to the thickness difference between the two NiFe layers. Our experimental results on the effect of the biquadratic coupling on the mode frequency variations are in good agreement with the theory.