Elastic (Jahn–Teller) domains and magnetic domains in the tetragonal spinel Mn2FeO4 were studied using X-ray double-crystal topography, X-ray diffractometry and the colloid-SEM method. The Jahn–Teller domains of the measured samples are tetragonal with the [001] c-axis alternating perpendicularly (thick domains) and parallel (thin domains) with respect to the growth direction of the specimens. Boundary interfaces are of the (110) type consistent with the cubic spinel system. A complex magnetic domain structure is discussed in relation with the crystallographic orientation of the Jahn–Teller domains.

The stripe model of domain structure in multilayers is studied by micromagnetic simulation. The results indicate a strong reduction of the effective domain wall energy (by dipolar effects). Domain width measurements on sputtered Co/Pd multilayers are compared with the theory. The estimated exchange stiffness is comparable with that of bulk Co. The effects of interface roughness and of interlayer exchange are discussed.

A combined investigation of the magnetization, Faraday rotation, polar Kerr rotation and the X-ray photoelectron spectroscopy of two Co- and Ti-substituted hexagonal ferrite films, prepared by pulsed laser ablation deposition, was made. The investigation indicates the presence of a certain amount of three valent cobalt ions within the majority of two valent cobalt states.

Domain sizes in demagnetized samples are reported for polycrystalline films of thickness down to 30 nm and for thin single crystal weges of pure and Co/Ti doped BaM hexaferrites. The results compare well with domain theory which is amended by taking into account results of micromagnetic computations.

CoTi-doped barium hexaferrite films prepared by pulsed laser ablation deposition, are investigated by XRD, EPMA and VSM magnetometery. The film properties are examined and compared with corresponding quantities measured on single crystals of the same compositions.

The thickness dependence of the domain period in pure and Co/Ti doped BaM hexaferrite polycrystalline films and wedge form single crystal platelets is studied by the colloid—SEM (scanning electron microscope) method. Experimental data on equilibrium domain periods are comparedwith the theoretical ones. Theoretical extrapolation allows to estimate the ‘critical’ film thickness below which the equilibrium domain period increases for various compositions.

The influence of the surface conditions of a series of the polycrystalline Co/Pd multilayers on the spectral dependence of the polar Kerr rotation, theta(k), was studied. Starting from low values, \theta(k)\ was found to increase towards short wavelengths, reaching 0.2 degree at the blue region. Using angular resolved photoelectron spectroscopy the oxidation states and the binding conditions of Co and Pd nearest surface layers were examined.

The observations of submicron domain structure of Co/Pd multilayers at various parts of the M-H loop and after different magnetization cycles designed to approach the global-equilibrium domain width are reported. The wall energy densities were estimated from comparison of the measured equilibrium domain width with the anhysteretic model predictions and also compared with the wall energy densities determined from the slope of major M-H loop.

Domain observations and measurements of mean domain sizes in Co/Pd multilayers with high perpendicular anisotropy are reported and compared with the predictions of the stacked-stripe model of domain structure. The estimated high wall energies are consistent with measured anisotropy. The properties of the model in the thin-layer limit are discussed

The domain structure in hexaferrite platelets was studied for various cobalt concentrations, 0≤x≤0.78, using the colloid-SEM method, with a view towards the possible applications of thin films of such materials in high density magnetic recording. Typical surface undulation of Bloch walls was observed in thicker platelets. The domain period decreases with decreasing crystal thickness and also with increasing cobalt concentration. The critical sample thickness for the transition from undulated to simple stripe structure was measured on a wedge-form sample and compared with the theoretical estimates.

Spectral dependences of the optical absorption and the Faraday rotation of Co- and Ti-substituted barium hexaferrite single crystals were measured in the 800–2400 nm wavelength region. The observed behaviour was explained by single ion contributions of paramagnetic and diamagnetic-like transitions due to cobalt ions present on tetrahedral sites.

The aim of this paper is to describe in detail our experience with the colloid-SEM method, especially as far as the colloids are concerned, to summarize the results which we obtained on CoCr films using this method, and to show some advantages and disadvantages of this method in comparison with the digitally enhanced Kerr technique.

Domain periods in low coercivity Co-Cr films were measured on minor and major loops and the differences are correlated with the observed coercivity enhancement on minor loops.

Domain structures of two low coercivity (Hc/Hk ≈ 0.02) and one medium coercivity (Hc/Hk ≈ 0.05) films were observed by the colloid-scanning electron microscopy (SEM) method in d.c. magnetic fields applied normal to the surface. The dependence of the submicron domain period on ascending and descending fields was measured. Anhysteretic curves were obtained by the superposition of a slowly decreasing a.c. field on the given d.c. field. The field dependence of the anhysteretic domain period is compared with the theory of Kooy and Enz. In addition to the visual measurement, the domain period was also determined by a two-dimensional Fourier analysis of the SEM photographs.

Using the colloid-scanning-electron-microscope (SEM) method, an investigation was conducted of the domain structure of CoCr films (400-1740 nm thick) at different points of the hysteresis loop. In some cases, an AC field exceeding the value of the coercive force was applied in addition to the DC field. For low-coercivity samples (H/sub c//H/sub k/ approximately 0.02) a bubble structure, which is e...

The domain structure of a CoCr film was studied in different magnetic fields using the method of a combination of the colloid technique and scanning electron microscopy (colloid-SEM method). The results obtained are presented and the advantages of this method are discussed.

Recently a considerable attention has been given to the study of CaGe:YIG, Ca:YIG, CaGa:YIG epitaxial films in connection with the observed low temp,erature magnetization anomalies [I-41. These effects were ex- plained on the basis of the assumption that towards lower temperatures the hole is gradually localized and forms the tetrahedral ~e~+ (d) ion, which is ferromag- netically coupled to the octahedral ~e~+ (a) ioqs. (Ac- cording to the Goodenough-Kanamori rules we would rather expect the antiferromagnetic interaction.) The purpose of the present work is to bring further.infor- mation on the simple system Ca:YIG and to discuss possible explanations. Fig.

The dependence of the submicron domain period of CoCr films in ascending and descending fields (dc: 8-320 kA/m; superposed ac: 0-55 kA/m) normal to the surface was investigated using the colloid-SEM method. Low coercivity samples (Hc/Hk ~ 0.02) were measured. Comparison with calculations furnished fair agreement in contradistinction to samples having H c/Hk ~ 0.05. The exchange constant A was deteremined from the thickness dependence of the domain period.

Spectral and temperature dependences of the Faraday rotation and X-ray photoemission spectroscopy of YIG: Ca garnet films have shown features characteristic for the presence of tetravalent iron ions in tetrahedral positions. The charge compensation of ca2+ by ~ e * + ions becomes saturated at 0.16 Ca per formula unit suggesting the existence of 0ions at higher calcium conte~ts.