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Laser-induced irreversible modifications of magnetic properties of molecular beam epitaxy grown X/Co/Y trilayers on Al2O3 substrates were investigated, with combinations of nonmagnetic metals Pt and Au as buffer X and capping layer Y. It is shown that the formation of regions with irreversibly rotated magnetization from in-plane to out-of-plane orientation occurred for Pt/Co/Pt, Pt/Co/Au, and Au/Co/Pt trilayers. In the Au/Co/Au system, the modification of magnetic properties was negligible. Pt/Co/Pt trilayers were also deposited by sputtering on Si/SiO2 substrates. In this case, a significant suppression of laser-induced magnetic modifications was observed and correlated with the lower thermal conductivity of the Si/SiO2 substrate.

Spatial distribution of magnetization in an ultrathin ferromagnetic Co layer with a lateral gradient of magnetic anisotropy, while approaching spin reorientation transition (SRT) (from perpendicular to in-plane magnetization alignment), has been investigated by means of micromagnetic simulations in the 2-D mode, using OOMMF software. The geometry of the out-of-plane-magnetized domains (parallel stripes, labyrinth, and bubbles) has been found to be dependent on both the initial distribution of magnetization and the direction of the applied magnetic field. A fast decrease in the domain size has been observed while moving toward SRT. In the experiment, Pt/Co/Pt layers with initial in-plane magnetization orientation have been irreversibly modified by femtosecond laser pulses. In the irradiated spot, rings with induced perpendicular magnetic anisotropy have been formed, resulting in an appearance of several local SRTs. Magnetic domain structure in the SRT regions has been visualized using magnetic force microscopy. The experimental observations are qualitatively explained by the results of the micromagnetic simulations.

Because of the importance of the surface magnetic properties for the optimal operation of magnetic sensors based on giant magneto-impedance effect (GMI), for the last few years we have studied the surface magnetization reversal and surface domain structure of glass-coated microwires using the magneto-optical Kerr effect (MOKE) technique [1]. Taking into account that the Curie temperature of Co-based microwires lies in the temperature range of approximately 100–450°C (depending on chemical composition), the surface magnetic structure should experience great transformation in a temperature range higher than room temperature. Moreover internal stresses induced by glass coating are the characteristic feature of glass-coated microwires [2]. Obviously the strength of internal stresses depends on temperature. Therefore now we direct our efforts to a new area of the investigation that is very important for the stable operation of magnetic sensors that use microwires as active elements — the influence of changing temperature on the surface magnetic structure.

Magnetization processes were investigated by employing magnetometry and magnetic domain imaging using magnetooptical longitudinal and polar effects in Fe 60 Al 40 films of 40 nm thickness. The films were initially chemically ordered and weakly ferromagnetic, and a large increase in the saturation magnetization was achieved through chemical disorder induced by Ne + -ion irradiation. Various sample geometries were investigated: 1) continuous film; 2) homogenously irradiated wire; and 3) magnetic stripe-patterned wire. Magnetization reversal and magnetic domains formed under the influence of the above sample geometries are reported.

We report about magneto-optical studies of magnetization reversal processes and magnetic domain structures in rare-earth Bi-substituted iron garnets in a wide temperature range. Measurements were done by a standard magneto-optical technique in Faraday geometry. Changes of both hysteresis loops shape and magnetic domain structures with temperatures indicate the presence of the branching domain structures above 130 K and the compensation temperature at 96 K.

In this paper, magnetic states and magnetization reversal of perpendicularly magnetized monodomain dots with a lateral size of hundred nanometers induced in a Co layer by a structured buffer are investigated by means of magnetic force microscopy. The experimental results have been successfully reproduced by micromagnetic simulations using an object-oriented micromagnetic framework. The factors responsible for the dots' behavior are discussed in details.

We report investigations on crossed magnetic field-induced transformation of surface domain structure in amorphous glass covered microwires. The study has been performed by a magneto-optical Kerr effect technique using optical microscopy. The existence of elliptic domain structure has been demonstrated experimentally. The formation of the domain structure with periodically inclined domain walls caused by the circular magnetic field was found in the surface of microwires.

Results of domain structures observation of individual Ni80Fe20 and Co sublayers in sputter deposited (NiFe/Au/Co/Au)10 multilayers, using an element-sensitive method: the photoemission electron microscopy combined with soft X-ray magnetic circular dichroism, are presented. Also, overall domain structures were studied with magnetic force microscopy. The studies allowed us to reveal submicron stripe domains in the investigated samples and the replication of the stripe domains from the Co layers with perpendicular anisotropy to the NiFe layers with easy-plane anisotropy.

Material selective sensitivity of a magneto-optical polar Kerr effect to magnetizations of films from different materials in a multilayer system is presented. The method is supported by rigorous modeling of magneto-optic response from the multilayer system and by experimental demonstration on the periodic cobalt-permalloy multilayers [Ni80Fe20(2 nm)/Au(2 nm)/Co(0.4, 0.8, and 1.2 nm)/Au(2 nm)]10 .

The aim of the paper is to study the magnetization processes and magnetic domain structure in epitaxial ultrathin Co films grown on stepped Si(111) substrates. The surfaces after Cu and Au/Cu coverage were investigated using in situ STM technique. The thickness driven evolution of hysteresis loops corresponds to spin-reorientation transition above 7 monolayers (ML) Co thickness. The in-plane magnetic anisotropy symmetry was deduced from magneto-optical (MOKE) hysteresis loops. The experimental data are discussed taking into account contributions of both perpendicular and in-plane uniaxial step-induced anisotropy. The preference of domain wall propagation for 3 and 5 ML Co thicknesses could be explained by the step-induced in-plane magnetic anisotropy determined from in-plane MOKE measurement.

We report investigations on influence of high-frequency electric current on surface magnetization reversal and surface domains nucleation in amorphous glass covered microwires. Magneto-optical Kerr magnetometry and microscopy have been used. A strong change of surface magnetization reversal and the transformation of the surface domain structure induced by electric current within a frequency range of 100 Hz-15 MHz have been found.

In this paper, we report investigations on circular magnetic domain structure in amorphous microwires. Polar magneto-optical Kerr microscopy was used for the observation of the magnetic domains images. The surface magnetization reversal is determined basically by the circular domains nucleation. For the first time, the rearrangement of the surface domain structure is observed as a part of the magnetization reversal process in amorphous microwires.

The general method of the effective domain wall mass calculation for an arbitrary model of a ferromagnet using the analysis of some simple functional extremum is proposed. The results, which illustrate the method, were obtained for the uniaxial ferromagnet placed in a magnetic field perpendicular to an easy axis. A comparison with previously used calculation procedures is also provided. >

The photoinduced changes of the magnetization vector orientation under the optical linearly polarized irradiation (/spl lambda/=0.53 /spl mu/m and /spl lambda/=1.06 /spl mu/m) were observed in ferromagnetic films (YCa)/sub 3/(FeCoGe)/sub 5/O/sub 12/. The effect is a result of the occurrence of the photoinduced anisotropy. The phenomenologic description based only on general symmetry consideration is suggested. >

The magnetic domain structure in (YCa) 3 (FeCoGe) 5 O 12 films grown on {100} GGG substrates was investigated at room temperature. These films show unexpected low domain wall motion. Some unidirectional properties (eg. relaxation time, domain structure vanishing field) of the samples have been reported in this work. These properties can be changed using an external magnetic field.