Hiromi Oike

X-ray magnetic circular dichroism on Co monodispersive cluster assemblies

X-ray absorption near edge structure (XANES) spectra and x-ray magnetic circular dichroism (XMCD) spectra at the Co K edge have been measured for Co clusters with the mean diameter d = 6-13 nm. The spectral analysis indicates that the fcc phase is predominant for d = 6 nm, while the hcp phase gradually increases with increasing d in agreement with the results of transmission electron microscopy. The 4p orbital moments of clusters tend to decrease in the smaller cluster, but the reduction is small compared with the case of the multilayers, suggesting the importance of surface effects of the Co cluster system.

Magnetic Compton study of a USe single crystal

Magnetic Compton scattering experiments on a USe single crystal have been performed at several temperatures around the Curie temperature of the specimen. The spin and the orbital moments of USe are deduced by combining the magnetic Compton scattering experiment with the magnetization measurement. Furthermore, the spin moment of USe is decomposed into a 5f electron component and a diffused component. We have obtained the spin moment of the 5f electron , the orbital moment of the 5f electron and the diffused moment . From comparison with the previous results of UTe, it is concluded that the increase of the total magnetization from USe to UTe can mainly be ascribed to the decrease in magnitude of spin moment of the 5f electron with a slight increase of the orbital moment of the 5f electron. The results are also discussed from the points of view on the hybridization between U 5f and U 6d electrons and/or U 5f electrons and valence electrons of chalcogenide.

X-ray magnetic circular dichroism in Pd/Co multilayer system

Abstract We have measured X-ray magnetic circular dichroism of Pd/Co multilayers at the Pd L2,3 edges and the Co K edge. The orbital moments of Pd 4d electron are small and the polarization of Pd 4d mainly comes from spin contribution. No corresponding enhancement of spin–orbit interactions on the Pd sites is found in the perpendicular anisotropic multilayers. The spin moment of Pd 4d in this experiment is close to the calculated value. The orbital moments of Co 4p electron are small in thinner Co layer suggesting the localization of Co 3d electron.

Magnetic phase diagram of Fe–SiO2 granular thin films

Abstract DC and AC susceptibility measurements on Fe–SiO 2 alloys have been carried out from room temperature to liquid He temperature in the zero field-cooling (ZFC) and the field-cooling (FC) mode. The magnetization in the ZFC mode increases rapidly below a characteristic temperature, T c , and decreases below the freezing temperature, T f , both of which depend on the applied magnetic field, frequency and Fe concentration. A magnetic phase diagram is described from these observations.