Papers by Author: Masayoshi Itou

Abstract: We have applied two kinds of experimental methods using elliptically polarized synchrotron X-rays, magnetic Compton and Bragg scattering experiments, to a single crystal of a disordered Pd_0.80Co_0.20 alloy, and have measured magnetic Compton profiles and magnetic form factors, respectively. The result of the Compton scattering experiment has shown that the electronic structure of Pd_0.80Co_0.20 is similar to that of Pd_0.72Co_0.28, and the spin moment has been evaluated. The result of the Bragg scattering experiment has reinforced that of the previous experiment [M. Ito et al.: Mater. Sci. Forum Vol. 459 (2011), p. 3.], and the spin moment estimated by the magnetic Bragg scattering has reproduced that by the magnetic Compton scattering. These results show that the joint study of the magnetic Compton and Bragg scattering provides a tool for investigating the magnetic property of alloys.

Abstract: Magnetic Compton profiles (MCPs) of Co/Au multilayers have been measured and analyzed by DV-Xα cluster model calculations from a viewpoint of perpendicular magnetic anisotropy (PMA). The PMA and the MCPs are discussed for the presently obtained results for Co/Au, along with the previously obtained results for Co/Pd and Co/Pt. A Co/Au multilayer shows a weak PMA which is caused by |m|=1 states of Co 3d electrons at a smooth Co/Au interface. The increase of the interface-to-volume ratio plays the main role in determining the perpendicular anisotropy in Co/Au multilayers. The strain of a Co layer can have a secondary role in determining the magnetic anisotropy in Co/Au multilayers, although the strain dominates PMA in the case of Co/Pd and Co/Pt multilayers.

Abstract: We have measured magnetic Compton scattering (MCS) for an Fe/MgO multilayer film at several magnetic field applying perpendicular to film plane. A spin specific magnetic hysteresis (SSMH) loop is obtained by the MCS for the Fe/MgO multilayer film. A knickpoint is observed in the SSMH loop around the magnetic field of 0.5 T. Orbital magnetization is enhanced within the magnetic field from-0.5 T to 0.5 T. A decomposition analysis for magnetic Compton profiles shows the suppressed |m|=0 states and enhanced |m|=1 and 2 states within the magnetic field from-0.5 T to 0.5 T. Here m denotes magnetic quantum number. The knickpoint corresponds to a perpendicular magnetic anisotropy, which comes from the enhanced |m|=1 and 2 state and orbital magnetization in the Fe/MgO multilayer.

Abstract: The effects of strain and interface roughness at the Co/Pd interface are investigated from the viewpoint of perpendicular magnetic anisotropy (PMA) using the DV-Xα cluster model calculation method. It is found that spin projected occupation number ratio of magnetic quantum number |m| = 2 for the Co 3d electrons enhances by expanding the lattice within a close-packed plane of fcc stacking and, hence, enhances the PMA. Rough interface decreases the spin projected occupation number ratio of |m| = 2 and, hence, decreases the PMA. These results explain the PMA properties of Co/Pd multilayers fabricated using molecular beam epitaxy (MBE) technique and RF sputtering techniques.

Abstract: We compare two Co/Pd multilayers with correspondingly smooth and rough interfaces. The first is a Co (1.5 nm)/Pd (2.6 nm) multilayer with a smooth interface deposited by the MBE technique, and the second is a Co (1.6 nm)/Pd (4.0 nm) multilayer with a rough interface deposited by the sputter technique. Both multilayers have almost the same perpendicular magnetic anisotropy energy, 1.15 Merg/cc for the Co (1.5 nm)/Pd (2.6 nm) multilayer and 1.20 Merg/cc for the Co (1.6 nm)/Pd (4.0 nm) multilayer, respectively. The symmetry of the wave function, which is measured using the magnetic Compton profile, is almost the same for both multilayers. This suggests that the smooth interface controls the wave function and enhances the PMA energy even if the Co/Pd multilayer has a thinner Pd layer.

Abstract: We have measured magnetic Compton profile of Co/Pd thin films sputtered on a substrate for studying the electronic structure. For the first time, a silicon nitride substrate of 100 nm thickness we used in the magnetic Compton scattering experiment. We have improved vacuum tubes of the Compton beam-line BL08W of SPring-8, and have reduced greatly the background scattering for the Compton profile. We have succeeded in measuring magnetic Compton profile of Co (0.8 nm)/Pd (1.6 nm) 400 nm multilayer.