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Problems involving polarized plane waves and currents on sheets perpendicular to the wavevector involve only one component of the fields, so it is possible to discuss electrodynamics in one dimension. Taking for simplicity linearly polarized sinusoidal waves, we can derive the field emitted by currents (analogous to dipole radiation in three dimensions) and reflection and transmission (analogous to Thomson scattering). Some aspects of the results are not intuitive, and for a physical understanding we need to see the problem in three dimensions. Eventually we apply these results to a linear model of the sheet, and we discuss the limit from a thick sheet. (Contains 1 figure.)

Thin Ni sheets were investigated to determine the effect of cold-rolling and recrystallization annealing.

Singularities of various kind are often observed in the magnetization curve of a ferromagnetic crystal. This is especially true for high anisotropy materials, such as the rare earth - intermetallic compounds. Examples are the First Order Magnetization Processes (FOMP), which are discontinuous rotations of the magnetization vector due to high order anisotropy terms. However, the hard direction anisotropy field of any ferromagnetic crystal is always a critical field at which it reaches saturation. The Singular Point Detection (SPD) technique allows detecting such singularities using polycrystalline samples by the observation of the successive derivatives [d.sup.n]M/d[H.sup.n]. The shape of the singularity and the order of differentiation 'n' at which it becomes apparent depends on the symmetry of the hard axis. The SPD theory has been recently extended to multidomain crystallites on the basis of the Neel phase theory, and utilized for texture studies of permanent magnets. Moreover it has been proved to be valid also in the presence of canting between the sublattice moments caused by strong competition between anisotropy and exchange; in principle, in the case of ferrimagnetic compounds it is possible to detect spin flop transitions both of second and first order (high FOMP). The application of the SPD approach to the general problem of the complex susceptibility tensor and its covariant derivatives can lead to further developments. As an example, the singularity observed in the transverse susceptibility of uniaxial materials is strongly sensitive to the presence of single domain crystallites.

Singular point detection for the measurement of ferromagnetic anisotropy fields in multidomain crystal samples was investigated. The results showed that the grain configuration was important since it determined the characteristics of the peak. Grains with same shapes resulted in a divergence peak while grains with different shapes exhibited peaks which were similar to experimental ones.

We present a study of the magnetic properties and magnetization processes in hard Co-Pt (Pt∼20 at. %) films. Co-rich Co-Pt films, with thickness t ranging from 5 nm up to 2 μm, were prepared by electrodeposition on (0001)-oriented Ru underlayers. All samples displayed strong perpendicular magnetic anisotropy and high coercivity. Virgin magnetic domain structures for varying thickness were investigated by magnetic force microscopy (MFM). The observed increase of domain width with film thickness is well understood by full two-dimensional micromagnetic computations with no adjustable parameters. The easy-axis magnetization process, as observed by measuring virgin curves by magnetometry and imaging the corresponding magnetization configurations by MFM in variable field, consists of two stages separated by a well-defined critical field, marking the onset of domain wall propagation. A thorough analysis of the out-of-plane angular dependence of the switching field points out that unpinning of domain walls is the dominant magnetization process. [ABSTRACT FROM AUTHOR]

Application of the two methods of single point detection and a least-mean-square to establish the orientation density of the tetragonal axes of the Nd2Fe14B crystallites in sintered Nd-Fe-B magnets reveals the similarity in the texture and intrinsic magnetic properties provided by both the methods as they are based on the reversible rotation of the local magnetic polarization. The temperature dependence of the anisotropy field of the magnetic main phase in incompletely textured polycrystalline materials can be estimated by using either of these methods.

On the basis of a phenomenological model of the anisotropic ferrimagnet, the analysis of the critical behavior of ferrimagnetic RE-TM compounds in dependence on the applied field and temperature has been carried out. The model has been applied to some [RE.sub.2][TM.sub.17] intermetallic compounds, in which the presence of the intermediate saturation has been experimentally verified by utilizing the SPD technique. The best-fit of the measured magnetization curves allows the achievement of information on the RE-TM exchange and on the RE and TM anisotropy and to predict the occurrence of spin-flop transitions at higher applied fields.

Deals with a study which analyzed the problem of how singular point detection in the magnetization curve is transformed in the case of a polycrystalline specimen. Examination of how the critical parameters of first-order magnetization processes were modified; Methodology of the study; Results and discussion.

Cobalt/iron multilayers with different layer thickness were electron beam evaporated in ultrahigh vacuum, keeping constant both the number of layers and the Co/Fe thickness ratio. Structural and magnetic properties are thoroughly investigated with different techniques. The multilayers have clean and sharp interfaces. All samples show single-phase magnetic behavior in the temperature range of 5–300 K, due to the strong exchange coupling between the layers. The room temperature hysteresis loops present a sharp switching at a field of ∼8 kA/m, followed by a residual hysteresis extending up to saturation, at fields of several tens of kA/m. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]