Graphene-nano-ribbon (GNR) is very attractive for ultra-high density spintronics devices. For checking a capability of ferromagnetism, FeO-modified GNR was analyzed based on the density functional theory. Model unit cell was [C₃₂H₂Fe₂O₂]. Among multiple spin states, the most stable spin state was S_z=6/2. Optimized atomic configuration and spin density suggested the 90 degree super-exchange coupling between Fe-3d and O-2p orbits. Magnetic moment of Fe-3d component was 2.48μ_B, whereas that of 4s was 0.10μ_B. Summed magnetic moment of Fe became 2.58μ_B. Magnetic moment of oxygen was 0.23μ_B. Sign of magnetic moment of Fe and O were both up-spin. These results suggested a super-exchange ferromagnetic order as like (-Fe-O-Fe-O-). Band analysis showed this system to be an insulator. Such a nanometer scale ferromagnetic material will be a promising candidate for many spintronics applications.

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  The combined magnetometric and microwave spectroscopy study of Fe/(Ga,Mn)As hybrids is reported. Temperature-dependent remnant magnetization data revealed unexpected non-monotonic behavior when measured along one of the in-plane crystallographic directions of (Ga,Mn)As, with a slope-sign change at the Curie point of the ferromagnetic semiconductor. Subsequent ferromagnetic resonance measurements presented uniaxial and cubic+uniaxial symmetries of in-plane magnetic anisotropy in Fe and (Ga,Mn)As, respectively. The apparent non-monotonicity of magnetization was explained as a manifestation of competition between the applied magnetic field and temperature-altered magnetic anisotropy in ferromagnetic metal layer.

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  In recent years, the importance of understanding dynamic properties of magnetic materials is increasing. For designing dynamic responses in ultrafast optical control applications to spintronic devices, clarifying intra- and inter-layer energy dissipation process and spin dynamics in multilayered systems is an important issue. In this study, we investigated layer-specific measurement of ultrashort laser-induced ultrafast demagnetization and precession in magnetically and electrically decoupled GdFeCo double-layered film by all-optical pump-probe method. After laser excitation, demagnetization level of the first magnetic layer located at pump light incident side is about 5 times as large as another layer within ～ps range. Furthermore, from a time evolution of Faraday rotation in recovering processes, it is found that lattice temperature of each magnetic layer equilibrates at ～400 ps. Finally, independent precessional oscillation of each magnetic layer is clearly observed.

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  Hologram memory is a promising data storage technology with a high recording density and fast data-transfer rate. Magnetic garnet media such as Bi_1.3Dy_0.85Y_0.85Fe_3.8Al_1.2O₁₂ (substituted rare-earth iron garnet, SRIG) films have advantages of rewritability and unnecessity of shielding. The diffraction efficiency of these garnet films, however, is not sufficient to apply to storage devices. In this paper, we proposed a use of magnetophotonic crystals (MPC) as hologram media and calculated their diffraction efficiency. The results indicated that MPC media showed a high diffraction efficiency compared with single SRIG films, and especially the MPC medium with the structure of substituted gadolinium gallium garnet substrate / (Ta₂O₅ / SiO₂)² / SRIG / (SiO₂ / Ta₂O₅)² with the SRIG thickness of 3.88 μm exhibited the diffraction efficiency of 0.36%. A large Faraday rotation angle and deep magnetic hologram fringe originated from the localization of light results in such a high diffraction efficiency.

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  Perpendicular magnetized tunnel junctions (MTJs), whose stack is [Co/Pd] / MgO / TbFe, were fabricated since the TbFe memory layer has a large perpendicular anisotropy and a low Curie temperature, which are suitable for thermally assisted (TA) switching. The TA switching of the TbFe layer due to a Joule heating created by a pulse current through the tunnel junction was confirmed. The MTJ with MgO 1.4 nm layer exhibited the MR ratio of 9 %, and the resistance area product RA of 342 Ωμm² at low bias voltage of 40 mV. The coercivity of TbFe at room temperature was about 1.5 kOe, while the magnetic switching at low magnetic field of 100 Oe was confirmed by the application of a current pulse with duration of 100 msec through the tunnel junction which creates the Joule heating. Moreover, the dependence of the power density necessary to switch the TbFe layer on the external applied field was measured. The required power density to complete the TA switching decreased linearly with the increase of the applied field and the TA switching of TbFe at low external field of 100 Oe was confirmed at the applied power density of 2.2 mW/μm².

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  Polarization properties in aperture-less scanning near-field optical microscopy (SNOM) were investigated using the 3D finite-difference time-domain (FDTD) method. We found that scattered light became elliptically polarized with linear or circular-polarized light illumination, and the polarization state of scattered light was preserved. In addition, Jones matrices that express the relationship between incident light and scattered light in terms of the polarization states were successfully obtained. We succeeded in calculating the polarization state of scattered light with arbitrary polarized light illumination by using the Jones matrix method.

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  Highly efficient coupling between light sources and plasmon antennas is extremely important to achieve successful thermally assisted magnetic recording. The energy efficiency obtained from combining a plasmonic waveguide (PW) with a surface plasmon antenna was studied. It was found that the efficiency of light energy propagation was improved from 0.5 to 18.8% by combining the PW and the surface plasmon antenna. It was also clarified that the incident angle of light into the PW as well as the layer structure of the PW were critical to the efficiency of the optics.

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  The magnetic response of surface plasmon polaritons (SPPs) has the potential to be utilized as a magnetic sensor. To this end, a non-solid solution material (Ag-Co system) was selected for evaluation, as such materials are expected to efficiently excite the SPPs, while also highly increasing the magnetic sensitivity with a single layer. In the Ag-Co non-solid solution film, Ag is a good SPP excitation material, whereas Co is a ferromagnetic material. The excitation and magnetic response of the SPPs in Ag-Co single layer films were investigated by varying the film thickness and wavelength, from which it was found that the optimal characteristics for both were obtained with films 35–50 nm thick. The largest magnetic response of the SPPs, as defined by the ratio of reflectivity change under the applied magnetic field between zero and 400 mT, was determined as ～0.29. The Ag-Co non-solid solution system therefore represents a good material for obtaining a large magnetic response of SPPs.

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  Femtosecond laser pulse excitation of multi-sub-lattice rare-earth (RE) transition-metal (TM) ferrimagnets opens the way to trigger ultrafast precessional switching and moreover all-optical magnetization switching (AOS). This AOS phenomena originated from sub-lattice nature is fundamentally different from conventional magnetic field driven switching mechanism. In this study, we show that the AOS efficiently works even near compensation composition ratio C_comp or compensation temperature T_comp that makes hardness to magnetic field driven net-magnetization (M_net) reversal. Under the various conditions of M_net, all optically created domain sizes were almost determined by only the condition of laser excitation. Furthermore, we suggested that the switching domain area can be estimated by a fluence threshold W_ft.

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  We fabricated FeCuPt grains by using a combination of Rapid Thermal Annealing with Rapid Cooling Process. The isolated grains consist of mostly L1₀-ordered and polycrystalline structure. We carried out additional annealing on these isolated FeCuPt grains to achieve single crystallization of grains. The surface morphology and detailed crystal structure of the grains are observed. After additional annealing, FeCuPt grains retained almost the same grain size. As a result, single crystalline L1₀-FeCuPt isolated grains were obtained by combining RTA with RCP and by carrying out additional annealing. Furthermore, we characterized the thermo-magnetic properties of single crystalline L1₀-FeCuPt isolated grains and increased areal grain density by forming additional grains.

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  Helicity-dependent photocurrent ΔI has been detected successfully under experimental configuration that a circularly polarized light beam is impinged with a right angle on a cleaved sidewall of the Fe/x-AlO_x/GaAs-based n-i-p double-heterostructure. The photocurrent ΔI has showed a well-defined hysteresis loop which resembles that of the magnetization of the in-plane magnetized Fe layer in the devices. The value of ΔI with a shunt resistance of 10 kΩ has been |ΔI| ～0.2 nA at 5 K under the remnant magnetization state. Study on temperature dependence of the relative ΔI value at H = 0 has revealed that it is maximized at temperatures 125 ― 150 K, and is still measurable at room temperature.

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  Dependence of photo-induced FMR (phi-FMR) on incident angle of excitation and probing laser beams has been studied in a [Co (d_Co = 0.78 nm) / Pd (d_Pd = 0.81 nm) ]₅ multi-layer film with the aim to find experimentally the limitation of inducement and detection of magnetization dynamics with oblique light incidence. We have found, in the experiments changing the incident angle of a pump beam, that phi-FMR is observed up to the grazing incident angle of 88° with p-polarized excitation pulses, whereas it disappears at the incidence angle of around 65° with s-polarized excitation. As for the experiments changing the incident angle of a probe beam, phi-FMR disappears at the incidence angle of 65° for both s- and p-polarizations, whereas it reappears with further increasing the angle for the p-polarization and vanishes at 75°.

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