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Tb-Co perpendicular magnetization films are mother materials for perpendicular magnetic recording media. Since the magnetic recording technique is based on magnetic switching of a material, investigating a magnetic the response of the material to a magnetic field is important. The magnetic response of the entire system is the net of each microscopic response of the spin magnetic moment and orbital magnetic moment of the elements. Herein we study the magnetization processes of the spin, orbital, and the element-specific magnetic moments by measuring the magnetic field dependence of the magnetic Compton profile of a Tb12Co88 film. The spin and orbital magnetic moments have opposite orientations. Similarly, Tb and Co magnetic moments have opposite directions. When the total magnetic moment reverses, the orientation of spin and orbital magnetization as well as Tb and Co reverse. Decreasing the temperature, the fluctuation of the magnetic moment of Tb in the perpendicular direction decreases. So the cancelation between the Tb and Co moments reduces total magnetic moment.

In this study, we measured the Compton scattering spectra of Al, Ag and Au metals changing the harmonic order of X-rays from an undulator. The width of the Compton scattered X-ray spectrum changed depending on the harmonic order of X-rays. This indicates that Compton scattering spectra shape reflects a momentum perpendicular to the traveling direction in Hermite–Gaussian (HG) light.

We investigated the magnetization process of Fe (110) film using the field dependence of magnetic Compton scattering and M\"ossbauer spectroscopy. From the magnetic Compton profiles, the spin and orbital magnetic moment specific magnetization versus magnetizing field curves were obtained. From the M\"ossbauer spectra, the angles between the magnetizing field and the magnetic moment were obtained. It was found that the magnetizing field dependence of the ratio between orbital moment and spin moment was related to the angles between the magnetizing field and the magnetic moment. We indicate that the magnetic field dependence of the orbital magnetic moment plays a role in the magnetization process., 本研究では磁気コンプトン散乱およびメスバーワー分光を用いてFe薄膜の磁化過程を詳細に調べた。磁気コンプトン散乱からスピン磁気モーメントと軌道磁気モーメントの磁化曲線を算出した。メスバーワースペクトルからは磁化と外部磁場のなす角の印加磁場依存性を調べた。これにより磁化曲線の振る舞いは磁化と外部磁場のなす角の変化と大きなかかわりがあることが分かった。

While the charge transfer between the transition metal and oxygen sites in transition metal oxides has been studied by resonant inelastic soft X-ray scattering, the charge transfer between transition metal sites has not been studied as of yet. In this study, we have measured the Ti 2p edge resonant inelastic X-ray scattering spectra of MTiO3 (M = Mn, Fe, Co, and Ni) in order to investigate the intermetallic M 3d–Ti 3d charge transfer. We found the peak around −4.5 eV in the energy loss scale for all MTiO3, which is attributed to the M 3d–Ti 3d charge transfer; whereas only FeTiO3 exhibits an additional intermetallic charge transfer peak at −2.5 eV. We attributed that the existence of the additional peak in FeTiO3 reflects the relation of M 3d and Ti 3d energy levels.

The charge ordering of Fe 2+ and Fe 3+ ions in LuFe 2 O 4 induces ferroelectricity below 330 K. In this study, the X-ray absorption spectra (XAS) at the Fe L 2,3 -edge are investigated to study charge ordered- and disordered-states. The polarization dependence of XAS revealed that the energy level of ( d xy , d x 2– y 2 ) is lower than that of ( d yz , d zx ). In the charge-ordered state, the Fe L 3 -XAS shows a double-peak structure, which is a characteristic of Fe 2+ and Fe 3+ ions. In the high-temperature region, the double-peak structure becomes a broad single peak, because of overlap with the thermally excited state.

Charge transfer is a key concept in understanding X-ray spectra of transition metal oxides. In this study, X-ray absorption spectra (XAS) and X-ray emission spectra (XES) at the O 1 s -edge of MTiO 3 (ilmenite: M = Mn, Fe, Co, and Ni) have been measured. It was found that the O 1 s -edge XES show the existence of not only oxygen–metal charge transfer but also intermetallic charger transfer. Moreover, the band gap of each ilmenite was evaluated to be 2.4–2.8 eV by measuring the distance between the spectra edges of XAS and XES.

We have carried out X-ray absorption measurements with its magnetic circular dichroism (MCD) of perpendicular magnetic films of DyxCo100−x (15⩽x⩽33) at Dy M4,5 and Co L2,3 absorption edges to investigate electronic and spin states of the Dy 4f and Co 3d states, respectively. The replacement of major spin between Dy 4f and Co3d is clearly observed in the spectra between 20⩽x⩽25. The expected values of the orbital angular moment ∣〈Lz〉∣ of Dy 4f were estimated to be 1.4–0.8 μB while that of Co 3d was estimated to be around 0.2 μB.

A metal to insulator transition in integer or half integer charge systems can be regarded as crystallization of charges. The insulating state tends to have a glassy nature when randomness or geometrical frustration exists. We report that the charge glass state is realized in a perovskite compound PbCrO3, which has been known for almost 50 years, without any obvious inhomogeneity or triangular arrangement in the charge system. PbCrO3 has a valence state of Pb(2+)(0.5)Pb(4+)(0.5)Cr(3+)O3 with Pb(2+)-Pb(4+) correlation length of three lattice-spacings at ambient condition. A pressure induced melting of charge glass and simultaneous Pb-Cr charge transfer causes an insulator to metal transition and ∼10% volume collapse.

We studied microscopic magnetic properties of each consistent atom in boron added CoNiFe electroless-deposited soft magnetic films, which is a promising candidate for the soft magnetic underlayer of the perpendicular magnetic recording medium, by X-ray absorption spectra (XAS) and magnetic circular dichroism (MCD) measurement. It was found that various monoxides and Fe sesquioxide coexisted with the metals at the upper part of the films. The results of MCD sum rule showed the expected values of orbital angular moment 〈Lz〉 for the film with macroscopic magnetic domain boundaries were larger than those of without domains at Co and Ni atoms and smaller at Fe atom. The appearance of macroscopic magnetic domain boundaries probably originated from the increase in 〈Lz〉 of Co and/or Ni atoms. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The soft x-ray absorption and magnetic circular dichroism spectra at the Co L2,3-edges of [Co/Pd]20 and [CoB/Pd]20 multilayered films, which were sputter-deposited in Ar gas containing N2 at room temperature, were measured to investigate the electronic and spin states of the films. The macroscopic magnetic properties, such as coercivity and saturation magnetization, and microstructural properties, such as grain size and preferred orientation, were markedly changed for the [Co/Pd]20 film by the B doping and N2 addition. The B doping and/or the addition of N2 gas caused appreciable changes not only in macroscopic magnetic properties but also in microscopic properties, such as the spin angular momentum and orbital angular momentum, throughout the multilayered film. On the other hand, a new spectral feature at the high energy side of the Co L3-edge peak in x-ray absorption spectra was found in only the films with N2 added. Thus, the microscopic properties, such as electronic and spin states, of the Co 3d electronic state for the [Co/Pd]20 and [CoB/Pd]20 films were changed by only the sputtering process with additive N2 gas.

X-ray absorption and magnetic circular dichroism spectra (XAS–MCD) of the Dy M 4,5 -edges of Dy x Co 100− x ( x = 15–33) thin films are measured. The advantage of element and orbital selectivity in the XAS–MCD measurements enables us to directly observe the magnetic moments of specified elements. The MCD intensity at the Dy M 5 -edge is maximum when the incident X-ray is normal to the surface and the incident angle dependence of the MCD intensity shows a sine curve. That gives us information about the angular distribution of the Dy magnetic moments with respect to the total magnetization direction and the opening angle of the cone. Applying the sum rule, the expectation value of orbital magnetic moment was estimated. The half opening angle of the random distribution of the moments were estimated and it was found that the angle has its minimum value around x = 20.

Intra-versus inter-site electronic excitations in NdNiO3 by resonant inelastic ultra-soft X-ray scattering at Ni 3p edge

Resonant Mn L α,β soft X-ray emission spectra of a colossal magnetoresistive manganese oxide La 1.2 Sr 1.8 Mn 2 O 7 have been measured at the Mn L 2,3 -edges excited by monochromatized undulator radiation. The excitation energy dependence of the spectra has been analyzed in terms of d – d and charge-transfer excitations. The experimental spectra are reproduced by the multiplet calculation for the Mn 3+ configuration, which is consistent with the dominant occupancy of the 3 d x 2 - y 2 orbital and probably a phase separation.

Soft X-ray induced chemical evolution from glycine (Gly) to glycyl–glycine (glycine dimer or Gly–Gly) was studied for sublimated films of Gly. Values of quantum yield of Gly dimer formation were determined by high performance liquid chromatography (HPLC) technique to be: (1.2 ± 0.2) × 10 −1 for 400 eV, (4.6 ± 0.5) × 10 −2 for 407 eV and (3.2 ± 1.5) × 10 −2 for 860 eV irradiation, respectively. We measured X-ray absorption spectra of irradiated Gly films at near edge region of nitrogen K-edge, as a function of X-ray dose. Formation of Gly–Gly was confirmed by the appearance and growth of 402 eV peak, which is a fingerprint of the peptide bond. The important role of surface to chemical evolution is discussed.

The O Kα soft X-ray emission and absorption spectra (XES and XAS) of La 1.2 Sr 1.8 Mn 2 O 7 were measured at selected excitation energies using synchrotron radiation in order to investigate the electronic structure. The dependence of O Kα XES on excitation energy was observed. It is attributed to the 2p partial density of states of inequivalent oxygen sites. It was found that O(1) atom makes Mn 3d 3 z 2 − r 2 orbital stable.

The electronic structure of Eu 1− x Dy x TiO 3 is investigated by means of soft X-ray absorption spectroscopy (XAS) near the Ti L 2,3 -edges. The spectrum of EuTiO 3 shows a satellite structure in the high-energy side of four main peaks. The spectra analyzed by using a full-multiplet calculation and the observed features are almost reproduced by the cluster model. The satellite structure above four main peaks is due to the charge transfer (CT) from the O 2 p orbital to the Ti 3 d orbital. The intensity decreases with the composition of Dy. This tendency corresponds to the change of conductivity against x . This result means that the intensity of the charge transfer peak is strongly related to the conductivity in Eu 1− x Dy x TiO 3 . The charge transfer from the O 2 p orbital to the Ti 3 d orbital plays an important role in the conductivity in EuTiO 3 . According to the values of the parameters (charge transfer Δ, Coulomb interactions U dd , U dc ) obtained by the theoretical calculation, EuTiO 3 is an intermediate between the Mott-Hubbard-type and Charge-Transfer-type insulator.

The electronic and spin states of [Co/Pd] multilayered perpendicular magnetization films with various seedlayers have been investigated by means of soft x-ray absorption and magnetic circular dichroism spectroscopy at the Co L2,3-edges. The expectation values of the orbital angular momentum 〈Lz〉 and the spin angular momentum 〈Sz〉 of Co atom in the [Co/Pd] multilayered film were estimated using the sum rule. It was found that the seedlayer changes macroscopic magnetic properties of the [Co/Pd] multilayered film without affecting the electronic and spin states of the upper layers of Co.

The electronic and spin states of the perpendicular magnetization films of Tb17 Feχ Co (83-χ_) (χ=0, 9.5, 32.5, 61.4 and 74.5) were measured by means of soft Χ-ray absorption and magnetic circular dichroism spectroscopy for Tb element to investigate the magnetic anisotropy. The origin of the magnetic anisotropy is said to be caused by a large orbital moment of the well-localized 4ƒ electron. The expectation values of orbital moment for the different composition of Fe were estimated to be about 1.2 μB applying a sum rule for the spectra. Using a theoretical model calculation the opening angle of the conical distribution of Tb moment along the easy axis of magnetization was estimated to be about 67 degree.

The photoion yields from O+ to O2+ were measured in the 1s–2p autoionizing resonance region of the 525–540 eV photon energy range. A multiconfiguration Dirac–Fock calculation was performed to interpret the experimental data and the results show fairly good agreement with the experimental ones. Photoionization of the N-like isoelectronic sequences of O+ and Ne3+ are discussed.

Magnetic circular dichroism (MCD) spectra of CrFe 2 O 4 have been measured by using the helicity switching method. The method achieves a high signal-to-noise ratio and resolved the fine structure in these spectra. The theoretical spectra, which were calculated by the charge transfer model, reproduced the experimental spectra. The origin of three negative peaks around the L3 edge in Cr 2p-MCD is attributed to the [Formula: see text] electron configuration in the initial state.

We have performed Co 2p X-ray absorption spectroscopy (XAS) on a mixed valence hexagonal layered system NaCo 2 O 4, which shows large thermopower and metallic conductivity. We also measured XAS for SrCoO 3 and LaCoO 3 as examples of typical Co ionic states. The Co ions of the last two materials are octahedrally surrounded by oxygen atoms. A Co atom in NaCo 2 O 4 also has octahedral coordination with oxygen atoms but it is distorted slightly. The Co ions in SrCoO 3 and LaCoO 3 are in the d5 and d6 configuration respectively. The spectrum of NaCo 2 O 4 resembles that of LaCoO 3 rather than that of SrCoO 3; the Co ions in NaCo 2 O 4 can be regarded as the d6 configuration. Also, we have tried to calculate the XAS spectra by using the charge-transfer multiplet model (CT-M). Although we could not find out the best-fitting parameters, the results suggested the itinerancy of the Co 3d states.

An understanding of the microscopic processes underlying the magnetization of the thin films is essential to the design and development of efficient magnetic recording media. In this context, we measure the magnetic Compton profile (MCP) of Tb x Co100−x films (13 x 20) and investigate the microscopic (spin magnetic moment (), orbital magnetic moment (), and element specific magnetic moment ( and )) magnetization processes. Using the magnetic-field dependence of MCP, we obtain the spin- and orbital-specific magnetization curves (SSMH and OSMH, respectively). From the profile-fitting analysis, we also obtain the element specific SSMH curves, and we find from our results that the ratio is nearly constant. Thus, it is assumed that the magnetic switching processes of and cooperatively occur in this system (corresponding to and ). In addition, we observe that and are −1 at x 17. This implies that the magnetic moment of Tb aligns toward the magnetic field in the region of x > 17 and that of Co aligns toward the magnetic field in the region of x < 17. We estimate that this value of x 17 is the compositional point that corresponds to the compensation composition of Tb and Co.

The electronic structure of CuGeO3 has been studied using soft X-ray absorption and emission spectroscopy. The unoccupied and occupied valence states are reflected by O 1s absorption and OK alpha emission spectra, respectively. An absorption pre-peak appe

Resonant soft X-ray emission spectra have been measured at the Ni 2p edge of a planar nickel complex K2Ni(CN)4·H2O and interpreted by performing ab initio configuration interaction calculations. This cyano complex shows characteristic metal-to-ligand charge transfer (MLCT) bands in the Ni 2p photoabsorption spectra. Resonant soft X-ray emission via the MLCT intermediate states can be interpreted as valence MLCT excitations within a one-electron picture. On the other hand, resonant soft X-ray emission via the intra-atomic Ni 2p–3d intermediate state corresponding to the white line excitation shows significant electron correlation effects.

A study of the electronic structure of ultrathin AlAs layers buried in GaAs(100) and their interfaces is presented. Al L-2,L-3 soft-X-ray-emission (SXE) spectra from the AlAs layers were measured. ...

Ultrathin AlAs(100) layers of 1-, 2-, and 5-ML thickness buried in GaAs are investigated by nb initio calculations. Unique experimental soft-x-ray emission spectra are explained in terms of interfa ...

The electronic structure of carbon nitride films has been studied using soft X-ray absorption and emission spectroscopy. Resonant N K-emission spectra show a strong dependence on excitation photon energies and the substrate temperatures, while C K-emission band appears insensitive to the different excitation photon energies and the substrate temperatures. Two nitrogen sites are assigned to N bonded to sp 3 -hybridized C and to N bonded to sp 2 -hybridized C.

We propose a new algorithm to achieve a very precise investigation of the three-dimensional atomic nucleus position in a material by the electron holography technique [T. Matsushita, A. Agui, Y. Yoshigoe, Europhys. Lett. 65 (2004) 207]. The algorithm is based on the “scattering pattern matrix” and an iterative gradient method, and it enables three-dimensional atomic-image reconstruction from a single-energy hologram. We measured a single-energy Si(0 0 1) photoelectron hologram of Si 2s emission using an Al Kα light source, and reconstructed the bulk structure with the use of the algorithm. We succeeded in locating as many as 29 atoms. The accuracy of the position for most atoms is within 0.05 nm.

We observed the natural circular dichroism NCD of amino acid films in the soft X-ray region for the first time [M. Tanaka, K. Nakagawa, A. Agui, K. Fujii, A. Yokoya, Physica Scripta, in press]. Based on the success, a new generation of detection system is now under preparation. Vacuum ultraviolet NCD of amino acid films was measured successfully using a polarizing undulator [H. Onuki, Nucl. Instrum. Meth. A 246 (1986) 94] installed at the TERAS electron storage ring at AIST, Tsukuba, Japan. A result of NCD measurement for alanine films is described in detail.

The Ti2p and O1s soft X-ray emission spectra were measured on rutile (TiO2) for the energy region of Ti2p and O1s excitation threshold. The ordinary fluorescence spectra resolve the Ti3d and O2p components in the valence bands. An elastic scattering peak is observed and resonantly enhanced at excitation energies corresponding to Ti2p absorption peaks. Furthermore, an inelastic scattering peak is observed. The peak is assumed to be caused by an elementary excitation that is charge transfer excitation from O2p valence band to Ti3d conduction band.

Soft x-ray emission(SXE) studies of several semiconductors and early transition metal compounds have been carried out. In the case of transition metal compounds, the comparison between photoemission(PES) and SXE spectra shows that the fluorescence spectra are consistent with PES spectra, but the elastic- and inelastic-light scattering spectra reflects the initial 3d states which may be related with the charge transfer state. On the other hand, the inelastic-light(Raman) scattering spectra of semiconductors have been measured in the energy region corresponding to the core exciton states. The Raman scattering spectra whose energy shifts in proportion to the excitation energy are found in the excitation energy region below the absorption edge. It is found that the Raman scattering of semiconductor emits the valence exciton as an elementary excitation.

Soft X-ray emission spectroscopy studies of c-BN have been carried out. We measured B1s- and N1s- SXES and their total yield (TY) spectra. A band gap energy was obtained to be about 6.2 eV. A strong core exciton structure was found in the B1s-TY spectra, but not found in the N1s-TY spectra. The B1s- and N1s-SXES spectra are consistent with the B2p- and N2p-partial density of states (DOS), but the B1s- and N1s-TY spectra are not consistent with the DOS curves of the empty state. As the photon energy varies, the shapes of SXES spectra are changed due to the inelastic-light-scattering effect.

Resonant soft X-ray Raman scattering measurements on NiO have been made at photon energies across the Ni 2p absorption edges. The details of the spectral features are identified as Raman scattering due to d-d and charge-transfer excitations. The spectra are interpreted within the single impurity Anderson model, including multiplets, crystal-field and charge-transfer effects. At threshold excitation, the spectral features consists of triplet-triplet and triplet-singlet transitions of the 3d8 configuration. For excitation energies corresponding to the charge-transfer region in the Ni 2p X-ray absorption spectrum of NiO, the emission spectra are instead dominated by charge-transfer transitions to the 3d9L-1 final state. Comparisons of the final states with other spectroscopical techniques are also made., Comment: 9 pages, 2 figures, 2 tables, http://iopscience.iop.org/0953-8984/14/13/324

The dynamical mechanism of ferroelectric phase transition in KDP-type crystals has been explained by the order-disorder model of locally distorted PO4 tetrahedrons through fitting of the factorized form of dielectric function including the relaxation mode. From this analysis no soft mode appears but the critical slowing down of the relaxation mode occurs toward to the transition temperature.

An application of magnetic Compton scattering as a new tool to measure a spin-specific magnetic hysteresis (SSMH) loop is introduced and its validity demonstrated. The applied magnetic field dependence of the integrated intensity of magnetic Compton scattering spectra, which reflect only the spin-dependent magnetic properties of magnetically active electrons, was interpreted as the spin-specific hysteresis. The spin magnetization of amorphous Tb(33)Co(67) film was observed and its SSMH loop exhibited qualitative agreement with the ordinal magnetic hysteresis loop measured using a conventional vibrating sample magnetometer.

The soft x-ray absorption spectroscopy (XAS) and magnetic circular dichroism (MCD) have been measured around the ${M}_{4,5}$ edges at $T=20$ and 300 K in order to investigate the electronic states of ${\mathrm{Eu}}^{3+}$ ions in ${\mathrm{Eu}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$. We found a structure in both the XAS and MCD spectra, which was not observed at $T=20\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, on the lower energy side of the ${M}_{5}$ edge at room temperature. By using atomic model calculations, the origin of the structure is assumed to be due to the thermal effect for the degree of admixture of the excited states ($J=1$, 2) and ground states $(J=0)$ of ${\mathrm{Eu}}^{3+}$. Developing the linear response model to investigate the magnetic moment obtained from the experimental spectra, we conclude that the thermal excited states of ${\mathrm{Eu}}^{3+}$ ions is the linear combination between $J=0$, 1, and 2 and the magnetic-field-excited state is the quantum-mechanically mixed state of the ground and excited states.

Eu1-xSrxMnO3 system is one of the perovskite manganites that exhibit the giant magneto resistance effect and the transition from the insulator phase to the metal. Eu0.6Sr0.4MnO3 behaves as a ferromagnetic semiconductor and has an Insulator-Metal (IM) transition induced by external magnetic field, which could be found only in this system among the perovskite manganites group. The mechanism of the transition was investigated by X-ray Magnetic Circular Dichroism (XMCD) at the Mn L 2,3-edges of and the Eu M 4,5 -edges in Eu0.6Sr0.4MnO3.

The occupied acid unoccupied valence band states of yttrium (Y) metal, Y dihydride and Y trihydride were measured by soft x-ray emission and absorption spectroscopy. The experiments were complement ...

Resonant inelastic scattering measurements of the conjugated polymer, poly(pyridine-2,5-diyl) have been performed at the nitrogen and carbon K-edges using synchrotron radiation. For comparison, molecular orbital calculations of the spectra have been carried out with the repeat unit as a model molecule of the polymer chain. The resonant emission spectra show depletion of the π electron bands which is consistent with symmetry selection and momentum conservation rules. The depletion is most obvious in the resonant inelastic scattering spectra of carbon while the nitrogen spectra are dominated by lone pair n orbital emission of σ symmetry and are less excitation energy dependent. By comparing the measurements to calculations an isomeric dependence of the resonant spectra is found giving preference to two of the four possible isomers in the polymer.

The magnetic Compton scattering of a Tb32Fe55O13 film was measured in order to investigate the microscopic magnetization processes (i.e., the spin moment, orbital moment, and element specific moments). The trend of the spin magnetic moment was the same as that of the total magnetic moment but opposite to the orbital magnetic moment. In the low magnetic field region, the magnetic moments were not perfectly aligned perpendicular to the film surface, and the perpendicular components were found to mainly arise from the magnetic moment of Tb. Oxygen atoms hinder long range magnetic interaction and hence also affect the magnetization process of the magnetic moments of Tb and Fe.

The B 1s exciton spectrum of the wide-band-gap semiconductor c-BN has been studied by resonant photoemission spectroscopy. The core-exciton band is found with a binding energy of about 1.2 eV. The constant-initial-state spectra for the valence-band features indicate that the B 1s exciton is the intermediate state for the resonant photoemission from the valence band. A satellite is found below the lower valence band by the resonant photoemission at B 1s exciton. The energy distribution curves of the valence band are qualitatively in agreement with the energy-band density-of-states curves but the discrepancy is conspicuous for the conduction band. The remarkable Fermi-level shift is found between p-type and n-type c-BN in accord with the rigid-band model, in spite of the large band-bending effect.

The magnetic properties reflected in a macroscopic hysteresis loop are dominated by both spin and orbital moments. In this study, spin-specific magnetic hysteresis (SSMH) and orbital-specific magnetic hysteresis (OSMH) loops were obtained for amorphous Tb43Co57 film by using a combination of Compton scattering and superconducting quantum interference device (SQUID) measurements. The shape of SSMH was found to be different from the shape of OSMH, and it was found that the contribution to SSMH from Co was different that from Tb. These results suggest that magnetic switching can be different among the spin moment, the orbital moment, and even the state of electrons.

Magnetic properties of [Tb20Co80/Pd(0.8 nm)]20 multilayered films with a TbCo layer of thickness 0.2–8.0 nm were studied using spectroscopic techniques of soft x-ray absorption (XAS) and magnetic circular dichroism (MCD) at the Co L2,3 and Tb M4,5 edges. The compensation layer thickness of TbCo, where magnetization becomes zero, was observed to be 5–6 nm. XAS and MCD analyses using the sum rule revealed that the existence of the compensation layer thickness was primarily because the projected Tb 4f magnetic moment was enhanced with the increase in the layer thickness, while the Co 3d moment was independent of the layer thickness. Below the compensation layer thickness, Co sublattice magnetization was dominant.

We measured natural circular dichroism (CD) for biomolecules in soft x-ray region for the first time. Natural linear dichroism (LD) for K(TiO)PO4 (KTP) crystal was also measured at the K-edge energy of oxygen. Measurements of CD and LD spectra were performed at the soft x-ray undulator beamline BL23SU of SPring-8 in Japan. In this beamline, an APPLE-2 type variable undulator was installed as a light source. This undulator was operated under the phase modulation mode in which left and right circularly polarized light (LCPL and RCPL) was switched with about 0.1 Hz. As a sample for CD measurement, we used sublimated film of L-, D- and DL-phenylalanine (Phe) and L- and D-serine (Ser) (thickness ~300 nm) and measured CD (AL–AR) spectra in the nitrogen and the oxygen K-edge region, respectively. Here, AL and AR mean the abbreviation of absorption for LCPL and RCPL, respectively. For the Phe film, we observed a negative peak at about 407 eV for the L-Phe spectra. On the contrary, a positive peak for the D-Phe spectra and no spectral feature for the DL-Phe were observed. For the Ser film, we observed positive CD peaks at around 540 eV and 548 eV at the L-Ser spectra, on the contrary, negative peaks for the D-Ser. These results are the first CD spectra for biomolecules in the soft x-ray region. We also used KTP crystal cut parallel to the plane (1,2,0) or (1,−2,0) as a sample of LD measurement and measured (AL–AR) spectra in the oxygen K-edge region and observed some peaks at about 530 eV. Since sign of these peaks were dependent on sample rotation angle in a plane perpendicular to the incident light, we concluded that these peaks are derived from linear anisotropy of crystal. Because of a weak linear polarization component of incident light, we could measure such LD spectra.

The X-ray emission yield by the Al-2p core-exciton excitation in GaAs/AlAs/GaAs heterostructures is studied theoretically: especially the angular correlation between absorbed and emitted X-rays are discussed. It becomes clear that the angular dependence of the X-ray emission yield is drastically changed according to the excitation character whether 2p → s or 2p → d transitions.