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Research into the structural and magnetic properties of sputtered Co/Cu multilayers in the pre- and postannealed states is presented. It was established that the interfaces in sputtered Co/Cu multilayers stay sharp and stable during annealing up to 600 deg C.

The magnetic properties of the system with particular attention to exchange biasing, coercive fields, and changes in the fourfold anisotropy of the Fe are studied. It is found that the system has a small exchange biasing effect and it shows a remarkable temperature-dependent enhancement of the usual fourfold anisotropy found in thin Fe films.

Ni80Fe20/Cu multilayers showing large giant magnetoresistance (GMR) at low magnetic saturation fields are discussed. In conclusion, it is the alloying tendency of Ni and Cu above 250 degree centigrade that determined the decay of the GMR and the change in the magnetic properties of NiFe/Cu multilayers.

We constructed a series of microstrip and co-planar microwave waveguides. These structures use metallic ferromagnets and therefore exhibit strongly frequency-dependent attenuation and phase-shift effects. The lines have maximum attenuation peaks occurring at the ferromagnetic resonance frequency, which increases with applied magnetic field. Such properties are used in band-stop filters. The devices used monocrystalline Fe films grown by Molecular Beam Epitaxy and polycrystalline sputtered permalloy films. For our devices that incorporated Fe the band-stop frequencies ranged from 10-20 GHz for applied fields up to only 80 kA/m (1000 Oersted). For devices using permalloy, the band-stop frequency was in the 5-10 GHz range for applied fields less than 80 kA/m. The maximum power attenuation was about 100 dB/cm, much larger than the previously reported values of 4 dB/cm. The resonance condition also affects the phase of the transmitted wave, strongly changing phase above and below the resonance frequency. The result is a phase-shifter that is tunable with applied magnetic field. We observed phase changes of over 360 [degrees]/cm with an applied field of less than 40 kA/m. Index Terms--Coplanar waveguide, ferromagnetic resonance, filter, microstrip, phase shifter.

We used molecular beam epitaxy to deposit a novel ferro-/antiferromagnet (Fe/KCoF[sub 3]) system on gallium terminated GaAs (100) substrates. We varied the thicknesses of single crystal Fe (001) layers from 1.05 to 3 nm. The antiferromagnetic fluoride, with a thickness of 30 nm, was deposited either in a single-crystal or a polycrystalline form, depending on the deposition conditions. KCoF[sub 3] is an antiferromagnet with a Néel temperature of 114 K. Its cubic structure almost perfectly matches the Fe film structure. The growth was monitored by reflection high energy electro diffraction. The magnetic properties of the system were studied using ferromagnetic resonance. Uniaxial and unidirectional anisotropy fields, due to exchange bias, were measured at low temperatures in the field-cooled samples and were smaller than 45 and 72 Oe, respectively. Both anisotropy fields, unidirectional and uniaxial, decreased with increasing thickness of the Fe film or with increases in temperature. The temperature dependence of the fourfold anisotropy was studied for the samples with different thicknesses of Fe films and different crystalline states of the fluoride layer. Room temperature values of the fourfold anisotropy also increased with increasing thickness of the Fe layer and were in a fairly good agreement with previously reported values for single crystal Fe films. Also, the temperature characteristics of the fourfold anisotropy for the structures with single crystal fluoride seemed to reproduce low-temperature literature data for Fe (001) films. In contrast, the structures with polycrystalline KCoF[sub 3] demonstrated a significant enhancement of the fourfold anisotropy at low temperatures. For the thinnest sample (t[sub Fe] = 1.05 nm) the low temperature anisotropy is more than tripled compared to room temperature values. It is believed that the surface effects can be responsible for this enhancement. [ABSTRACT FROM AUTHOR]