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The spatial distribution of magnetic properties studied by polar Kerr-effect-based magnetometry are carried out on an ultrathin cobalt wedge covered with a silver wedge whose slopes are perpendicular to each other and subsequently capped with a gold layer. The coercivity field was studied as a function of both cobalt thickness d and silver thickness h. A few monolayers of Ag were found to have a substantial influence on the coercivity field. A similar strong influence of silver coverage on the magnetic anisotropy field was observed. Domain structure evolution during magnetization reversal is investigated using an optical microscope. With an increase of the magnetic field, a magnetization reversal process occurs: first by domain nucleation and next by a domain wall movement towards the higher coercivity region of the sample. Changes of the fractal dimension of the domain wall as well as nucleation center density are investigated. A rapid increase of these parameters is observed while d increases towards the value of spin reorientation transition, which goes from easy-axis to easy-plane magnetization. Similar strong changes were observed while decreasing d to the lowest thickness available for observation. The problem discussed here, of tuning magnetic properties by silver-gold structure, is important from both a general physics and an application point of view, especially because of the possibilities for magnetic film patterning. [ABSTRACT FROM AUTHOR]

Magnetization reversal and domain structures in thin Co films in the thickness range 2 < d < 100 nm with in-plane magnetic anisotropy were studied. Both magneto-optical (MO) vector magnetometry and MO microscopy were used. A crossover of in-plane anisotropy symmetry from two-fold to six-fold was observed with increasing thickness of the Co layer from 2 nm to 100 nm. The evolution of the domain structure during magnetization reversal was studied for various orientations of the magnetic field relative to the anisotropy easy axis using a longitudinal Kerr MO microscope. [ABSTRACT FROM AUTHOR]

Abstract: The anisotropy of magnetic domain wall orientation as a function of ultrathin Co films thickness deposited on Mo (110) buffer has been studied by means of the polar Kerr effect in a polarizing microscope. Two types of magnetization reversal process induced by a magnetic field perpendicular to the sample plane, nucleation and propagation, have been observed, depending on Co layer thickness. A thickness-dependent coercivity field was determined from the analysis of the domain wall position during the reversal process. The preferential orientation of magnetic domain walls was found. [Copyright &y& Elsevier]

Abstract: Modification of anisotropy has been studied in Mo(110)/Co(0001)/Au structures grown by molecular beam epitaxy on a monocrystalline sapphire substrate. In order to fit the experimental data, the out-of-plane anisotropy energy contribution as well as that of the uniaxial in-plane were considered. Magnetic anisotropy constants as a dependence on Co thickness were determined in the range of spin-reorientation phase transition. Observed magnetic anisotropy can be explained by the presence of strains in Co film induced by the Mo(110) buffer. [Copyright &y& Elsevier]

Abstract: Kerr effect-based magnetooptical magnetometer was used to study the magnetization processes in thin Co layers (with thickness 1⩽d⩽31nm) grown on Mo(110) by MBE technique with hard magnetization axis normal to the sample plane. The in-plane anisotropy constant has a maximum of about 0.11MJ/m3 for Co thickness of 2nm. Magnetic after-effect was found in the magnetization reversal process measured under magnetic field applied along the in-plane easy magnetization axis. The estimated Barkhausen size is close to that determined for ultrathin Co and Pt/Co multilayers with easy magnetization axis perpendicular to the sample plane. [Copyright &y& Elsevier]

Magnetization orientation in Ga+-irradiated Pt/Co(dCo)/Pt ultrathin films can be changed in a controlled way by adjusting the ion fluence, F. Two-dimensional (dCo, F) diagrams of magnetic and magneto-optical properties have been derived. Distinct out-of-plane magnetic anisotropy states with enhanced magneto-optical effects were evidenced for specific (dCo, F) values. This rich behavior originates from two competing mechanisms: intermixing of Co and Pt atoms at the interfaces and the formation of ordered CoPt alloy phases with high magnetic anisotropy. The irradiation-induced effects open novel routes for both tailoring thin-film magnetic and magneto-optical properties and patterning of magnetic nanostructures [ABSTRACT FROM AUTHOR]

Abstract: The magnetic in-plane anisotropy as a dependence on Co film thickness in X/Co/X (where X=Mo or Au) sandwich structures were investigated by the ferromagnetic resonance method in the Co thickness range where magnetization is mainly in-plane oriented. The in-plane anisotropy was observed in all Au/Co/Au, Au/Co/Mo, Mo/Co/Au and Mo/Co/Mo samples. Large (up to 1.5kOe) in-plane anisotropy field was found for Mo/Co/Au sample which is related with anisotropic strain distribution during growth of Co(0001) on Mo(110) buffer layer. On the other hand, Mo as the overlayer has much smaller contribution to the in-plane anisotropy, which might be connected with pseudomorphic growth of Mo on Co with C3 symmetry. [Copyright &y& Elsevier]

A patterned buffer fabricated as Au islands self-assembled on an Mo layer surface locally affects magnetic properties (magnetic anisotropy, coercivity) of a deposited Co ultrathin layer. As a consequence, a system of elevated magnetic dots of a hundred nanometers in lateral size embedded in a magnetic matrix is obtained. Magnetization reversal of the patterned structure and magnetic states of individual dots are investigated by means of polar magnetooptical Kerr magnetometry and magnetic force microscopy, respectively. Despite a size distribution and the various shapes the perpendicularly magnetized dots adopt a monodomain state. [ABSTRACT FROM AUTHOR]