The effect of structuring GdFeCo thin films has been investigated in view of laser induced magnetic recording applications. It is found that patterning the substrate via electron beam lithography combined with reactive ion etching before the actual magnetic layer deposition can produce a significant magnetic de-coupling between the obtained structures and their immediate magnetic surrounding. However, upon laser heating, dipolar coupling with this surrounding is found to determine completely the magnetization orientation of the structures, a situation which could be problematic for laser induced recording applications. An alternative structuring approach, based on a lift-off technique of the magnetic layer, is immune to this problem since no magnetic surrounding remains.

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  Magnetization oscillations were excited in antiferromagnetically coupled Fe/Cr/Fe films using a time-resolved magneto-optical ‘pump and probe’ method. Both acoustic and optical oscillation modes were confirmed from Fourier transformation signals. The dependence of the excited frequency on the external magnetic field was characteristic of an antiferromagnetically coupled film, which was reproduced by the calculation based on a macro-spin model. In addition, it was found that a strongly coupled film (with a thinner Cr layer in this study) led to faster speed oscillations.

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  We investigate optical plane rotation and ellipticity at light reflection from a nonlinear optical dielectric film on a bigyrotropic magneto-electric slab. We have analyzed the optical nonlinearity and the magneto-electric coupling contributions to the ellipsometric parameters for both s- and p-polarized light at the incidence angles close to pseudo-Brewster angles.

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  One-dimensional magnetic photonic crystal with electro-optic and magneto-optic defect layers has been studied. The influence of the defect layers position inside a photonic crystal, as well as an action of a DC external electric field on the transmittivity spectra and Faraday rotation is investigated theoretically, taking into account the frequency dispersion of the system permittivities.

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  The multiple spin states of zigzag edge modified graphene molecules were analyzed to study the possibility of carbon based magnetic materials by using first principles density functional theory to select suitable elements for modification. Radical carbon modified C₆₄H₁₇ and dihydrogenated carbon C₆₄H₂₇ demonstrated that the highest spin state is most stable, which arises from the tetrahedral molecular orbital configuration in two up-spins at the zigzag edge. In contrast, oxygen modified C₅₉O₅H₁₇ exhibited the lowest spin state to be most stable due to the cancellation of four spins at the oxygen site. Boron modified C₅₉B₅H₂₂ had no π-orbit at the boron site, which meant the lowest spin state was most stable, whereas, C₅₉N₅H₂₂ had two π-electrons, where spins cancelled each other out to yield the lowest stable spin state. Silicon modified C₅₉Si₅H₂₇ and phosphorous modified C₅₉P₅H₂₂ had a curved molecular geometry due to large atom insertion at the zigzag site, which also brought about a complex spin distribution. Radical carbon and dihydrogenated carbon modification were identified as promising candidates for designing carbon based magnetic materials.

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  In this work the results of investigation of microcavity one-dimensional magnetophotonic crystals GGG (111)/[TiO₂/SiO₂]⁵/M/[SiO₂/TiO₂]⁵ are presented, where M is single (Bi_1,0Y_0,5Gd_1,5Fe_4,2Al_0,8O₁₂) or double(Bi_1,0Y_0,5Gd_1,5Fe_4,2Al_0,8O₁₂/Bi_2,8Y_0,2Fe₅O₁₂ or Bi_1,0Y_0,5Gd_1,5Fe_4,2Al_0,8O₁₂/Bi_1,5Gd_1,5Fe_4,5Al_0,5O₁₂) magnetoactive layers. Theoretical calculations and experiments showed that magnetooptical properties of microcavity one-dimensional magnetophotonic crystals can be improved using double layer iron garnet. In particular, the Faraday rotation can be significantly increased. It was determined, that depending on the crystal structure and magnetic layers composition magnetophotonic crystals with different types of magnetic anisotropy can be realized.

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  Magnetic inhomogeneities in dielectrics can be associated with certain electric polarization distribution since they locally reduce the symmetry of the magnetic crystal. This phenomenon known as spin flexoelectricity provides a way to electrically control micromagnetic structure. Our numerical simulations show that magnetic vortexes can be nucleated and stabilized in a magnetic nanodot by static electric field. The process of nucleation and dissipation of vortices is hysteretic. A material can be found, where both vortex and homogeneous states are stable in zero electric field, which provides a basis for an electrically controlled magnetic memory device.

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  We studied post-growth annealing of GaMnAs thin films with large film thickness t up to 100 nm. Our results show that for films of up to t = 100 nm comparable values of Curie temperature T_C and saturation magnetization M_s can be obtained as for t = 25 nm. Hence, the out-diffusion based annealing process is not thickness limited. Furthermore, anisotropic magnetoresistance (AMR) and planar Hall effect (PHE) measurements of as-grown and annealed samples are carried out to characterize the magnetic anisotropies of the different films.

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  Dual-cavity magnetophotonic crystals (MPCs) based on bismuth-substituted yttrium iron garnet (Bi:YIG) have been fabricated by a bonding method, and their structural, optical and magneto-optical properties have been studied. Identical structure of bonded fractions revealed the existence of the Fabri-Perot resonances in transmission spectra of single- and dual-cavity MPCs and corresponding enhancement of the Faraday rotation. However, the bonding interface was found to be unstable because of the bonding surfaces' roughness introduced by crystallization of Bi:YIG.

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  We propose a new test method for surface plasmon antennas applied to thermally assisted magnetic recording. Plasmon antennas were directly fabricated on a CoPtCr granular recording medium to maintain a distance between the antennas and the film. This method also makes it possible to prevent the antennas or media from becoming degraded. A silicon nitride dielectric layer was placed between the antennas and the magnetic layer to maintain a precise distance. We chose a thickness of 3 nm for the dielectric layer. Four hundred triangular Au antennas were formed on the medium with an E-beam lithographic technique. The written magnetic domains below the surface of the plasmon antennas were observed by magnetic force microscopy. Therefore, we were able to test the thermal effect of the plasmon antennas by directly placing them on the magnetic film.

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  We already reported^{1), 2)} that the rapid thermal annealing (RTA) of Fe/Pt and Fe/Cu/Pt multilayered continuous films are effective to obtain perpendicularly magnetized small L1₀-FePt grains on thermally oxidized Si substrate, and also the SiO₂ substrates having self-organized nano-pores is able to increase the grain density significantly. However, relations between the process for forming isolated grains from the continuous film and the annealing temperature are not clarified. Then, we fabricate FeCuPt by RTA, under the variety of heating up rate (T_R) and the maximum temperature (T_m). Isolated grains are obtained at higher T_R and T_m, however at higher T_m than approximately 550°C, large grains have been appeared. We introduce a rapid cooling process into RTA and comparing the results with the both cases of rapid and slow cooling processes to clarify at what temperature the isolation of grains has been occurred. With the rapid cooling process, a new peaks in XRD (Xray diffractometer) profile which correspond to the disordered structure of FeCuPt are appeared.

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  The optical near-field close to a nanostructure aperture is studied to generate a confined circularly polarized light for high density all-optical magnetic recording. It is revealed that a plasmon four-leaf clover aperture with magnetic particle media is able to create confined circularly polarized light. The four-leaf clover aperture combined with a square pattern particle medium can create confined circularly polarized light within 15 nm of spot diameter. It is also found that an off-track of 7.5 nm can be allowed in the proposed configuration. A four-leaf clover aperture is one of effective local surface plasmon transducers for all-optical magnetic recording.

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  The MO spectra of GMR structures with capping layers, Si/SiO₂/bottom electrode/TbFeCo (9 nm)/Cu (4 nm)/Co (0.1 nm)/Pt (1.1 nm)/(Pt (1.1 nm)/Co (6 nm)×4)/cap (cap = Ta, Au, Pt (3 nm)), were studied. We found that the optical constants and Kerr spectra exhibited different behaviors for all samples. The differences in the optical constants of these samples were analyzed by means of optical simulation. The MO spectrum is discussed in terms of simulation carried out by the virtual optical constant method for (PtCo)/cap (cap = Ta, Au, Pt (3 nm)).

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  With a vision that the technology for projecting spins/magnetic state on the polarization of light in a waveguide is worth developing, we have studied experimentally optical controllability of the dynamic state of magnetization, and the optical coupling between a magnetic medium and a waveguide. We describe experimental results on two-pulse control of the laser-induced magnetization precession in a ferrimagnetic GdFe thin film, as well as the evaluation of magneto-optical effect with oblique incident light through free space and a quartz prism.

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  It was recently proven by Belotelov et al. [J. Opt. Soc. Am. B 26, 1594 (2009)] how the magneto-optical (MO) transverse Kerr effect gets strongly enhanced when a smooth magnetic dielectric film is covered with a thin noble metal layer perforated with subwavelength slit arrays. This was attributed to the non-reciprocal influence of the MO substrate on the plasmon resonances of the noble metal grating. Here we extend on this work by studying how the thickness of the grating influences these extraordinary transmission effects and a surprising behavior is observed. At small gold thickness the strong enhancement at the Wood-plasmon anomalies is observed, as predicted before. The spectral position of these peaks is in accordance with the equation which is shown in the above mentioned paper. Surprisingly, when increasing the gold thickness the Kerr effect of the Wood anomalies is seen to weaken, disappear at a critical thickness (174 nm resp. 204 nm), and finally switch sign (all under fixed magnetization). We show that this behavior is caused by a critical coupling of the surface plasmons at the garnet-gold interface with grating air-slit cavity resonance modes.

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  In conventional magneto-optical (MO) recording which triggered with nanoseconds pulsed laser irradiation, the time scale of heat-up and cool-down process depends on thermal diffusion property in multilayered recording media. The speed limits of heating and cooling process are important issue for fast heat assisted magnetic recording. Femtosecond pulsed laser light allow excitation of magnetic systems much shorter than the time scale of thermal diffusion. In this study, we investigated the film structure dependence of ultrashort laser-induced demagnetization of 20 nm thick GdFeCo alloy films, under the variety of with / without intermediate dielectric layer and heat sink layer. After the laser excitation, we found two time region from magnetic behavior: rapid step-like reducing process of magnetization and following recovering process with precessional motion. The time scale of first rapid step-like demagnetization processes is conformed as within picoseconds range for all the cases.

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  The structure and magnetic properties of FePt films with a multilayered structure were investigated. An MgO layer was inserted between the top and bottom FePt layers. From X-ray diffraction patterns (XRD), in addition to a fundamental (002) peak, (001) and (003) superlattice peaks of the L1₀-FePt phase were clearly observed for all the samples, indicating that an FePt layer can be grown epitaxially on an MgO interlayer. A remarkable step in the magnetization curves in the direction perpendicular to the film plane was clearly observed for the films with an MgO interlayer thickness of more than 3 nm. From an in-field magnetic domain observation, three distinct states of magnetization, corresponding to the step in the magnetization curves, were clearly observed for the FePt(10 nm)/ MgO(10 nm)/ FePt(10 nm) multilayer film. This result is expected to provide fruitful information on multi-level magnetic recording for the future magnetic storage systems.

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