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By employing soft X-ray magnetic circular dichroism (XMCD) and soft X-ray absorption spectroscopy (XAS), we have investigated the temperature (T)-dependent valence and spin states of Cr ions in half-metallic ferromagnet CrO2 nanorod powder. The lineshape-analysis of both the Cr 2 p XAS and XMCD spectra of CrO2 reveals that the Cr ions in bulk CrO2 have both Cr 4 + t 2 g 2 ↑ and Cr 3 + t 2 g 3 ↑ valence configurations. This work provides the direct experimental evidence for the Cr 3 + - Cr 4 + mixed-valent states in bulk CrO2 ( Cr 3.8 + ) , demonstrating that the half-metallic ferromagnetism in CrO2 originates from the double-exchange interaction. The T-dependent intensity variation of the Cr 2 p XMCD spectrum agrees well with the bulk magnetization M(T) and the Curie temperature, indicating that the measured Cr 2 p XMCD data represent the intrinsic bulk ferromagnetism in CrO2, and support the above finding of the XMCD lineshape analysis.

We have investigated the angle-dependent orbital and spin magnetic moments of the [Co/Pd] multilayer (ML) films with intervening CoO layers under annealing by employing angle-dependent soft X-ray magnetic circular dichroism (XMCD). After annealing, the orbital magnetic moments of Co ions are found to be enhanced, with the maximum values along the perpendicular direction of [Co/Pd] ML, providing evidence for the origin of the improved perpendicular magnetic anisotropy (PMA) being the interface spin–orbit coupling. The induced Pd polarization was observed after annealing, demonstrating the strong Co-Pd hybridization arising from the Co-Pd alloy formation near the interface. The angle-dependent coercivity follows the 1 / cos θ behavior, suggesting that the magnetization reversal in the hysteresis curve in [Co/Pd] ML occurs mainly through the pinning mechanism.

The electronic structures of Sr 2 - x K x FeMoO 6 ( x = 0 , 0.1 , 0.2 ) double perovskites have been investigated by employing photoemission spectroscopy (PES), soft X-ray absorption spectroscopy (XAS), and soft X-ray magnetic circular dichroism (XMCD) near the Fe 2 p absorption edge. The substitution of K + ions for Sr 2 + ions causes the increasing Fe 2 + component in the Fe 2 + – Fe 3 + mixed-valent states, but little difference in the Fe 2p XMCD spectra. As x increases, the photoemission intensity near the Fermi level decreases, which indicates the decreasing carriers and the decreasing bandwidth of the itinerant t 2 g ↓ states.

Electronic structures of AgNi 1 - x Co x O 2 ( 0 ⩽ x ⩽ 1 ) delafossite oxides have been investigated by using photoemission spectroscopy (PES) and soft X-ray absorption spectroscopy (XAS). T 2p XAS ( T = Co , Ni) spectra of AgNi 1 - x Co x O 2 show that the valence states of Co ions are trivalent and do not change with x . In contrast, Ni ions are in the Ni 2 + – Ni 3 + mixed-valent states and the trivalent component increases with increasing x . This finding suggests that the metallic nature of AgNi 1 - x Co x O 2 for low values of x arises from the divalent Ni ions. The valence-band PES study of AgNi 1 - x Co x O 2 reveals that the Ni 3d states are more metallic like than the Co 3d states.

Electronic structure of epitaxial Co films on Pd(111) has been investigated as a function of the Co overlayer thickness, by using angle-resolved photoemission spectroscopy (ARPES). It is found that experimental band structures for Pd(111) and work functions for Co/Pd(111) agree reasonably well with the results of band structure calculations. Compared to Pd(111), valence band ARPES spectra of Co/Pd(111) support the existence of the induced magnetic polarization of Pd atoms near the interface, suggesting large hybridization between Co 3d and Pd 4d states near the interface.

Electronic structures of amorphous Fe x Zr 100− x alloys ( x = 90,91) have been investigated by using X-ray photoelectron spectroscopy (XPS) at room temperature. It is found that large energy scale features of the Fe 2p and 3s core level XPS spectra of these alloys are essentially identical to those of Fe metal, suggesting that local electronic structures around Fe atoms in these alloys are similar to those in Fe metal. It is expected that the basic mechanism for the magnetism in a-Fe x Zr 100− x alloys ( x ≈ 90) is same as that in Fe metal. On the other hand, core level shifts and much broader linewidths are observed in the Zr 3d core level XPS spectra of these alloys, as compared to Zr metal. The line shape analysis of the Zr 3d core level XPS spectra reveals that each spin—orbit-split component in a-Fe x Zr 100− x alloys ( x = 90,91) consists of two peaks, causing a broader total linewidth than in Zr metal. Possible origins for such composite structures might be two final states screened by different numbers of localized Zr 4d electrons and the existence of Zr atoms with different local environments.

Co/Pd multilayer films with a few atomic layers of Co were prepared on Si wafers by alternating deposition in an ultrahigh-vacuum physical vapor deposition system. The ultrathin structural parameters were measured accurately using only the angular positions of the X-ray diffraction peaks. The magnetic and magneto-optical properties were found to vary greatly depending on Pd predeposition and Pd sublayer thicknesses as well as Co sublayer thickness. The Pd-predeposited films were found to have a remarkably high coercivity of 4723 Oe and an interfacial magnetic anisotropy of 0.72 mJ/m 2 , which indicates their excellent potential as magneto-optical recording media.

The electronic structure of Mn12-Ac has been investigated using photoemission spectroscopy (PES) and X-ray absorption spectroscopy (XAS). The PES spectrum indicates that Mn 3d states are located near the top of the valence band, and the Mn 2p XAS spectrum provides clear evidence for the Mn3+–Mn4+ mixed-valent states.

The electronic structures of Mo-based pyrochlore oxides of R2Mo2O7 (R= Nd, Sm) have been investigated by using photoemission spectroscopy. The electronic states near EF are found to have mainly Mo 4d character, and they are not affected much by R 4f states located well below EF. The origin of the stable ferromagnetic phase in Nd2Mo2O7 is discussed in terms of the kinetic energy optimization.

Electronic structures of Co x Pd 100- x alloy films have been investigated using photoemission spectroscopy. The extracted Co 3d partial spectral weight (PSW) distribution exhibits interesting features at x = 25% reflecting large Co 3d/Pd 4d hybridization, and the Pd 4d PSW becomes broader as x increases. Calculated partial densities of states of Co x Pd 100- x compounds are found to be qualitatively consistent with experiment.

An electron spectroscopy study of the continuous α-γ transition in Ce 0.7 Th 0.3 has been made for temperatures between 100 and 310 K. A rough analysis of the results shows qualitative agreement with the Kondo Volume Collapse model, as derived from the Anderson Hamiltonian.