Investigation on Local Electron-Spin-Polarization in Nano-Structured Magnetic Thin Films in Equilibrium andNon-Equiibrium States

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Nuclear resonant scattering, a newly developing experimental method which can detect magnetic hyperfine field, was applied in order to study local electron-spin-polarization or local magnetism in nano-structured metallic thin films. X-ray beams corresponding to the Mossbauer transition energy of "Fe or rrsSn were monochromatized into a width of several meV and injected to the samples containing "Fe or rrsSn as nuclear probes. The X-rays resonantly scattered by the probing nuclei were recorded as a function of time to obtain "time spectra".After some optimization of the experimental setup, time spectra in good S/N ratio were successfully obtained for a monatomic "Fe layer deposited on a Cr layer. It was found that the time spectra were different among samples with different Cr layer thickness and also between samples with and without a ferromagnetic ssFe layer under the Cr layer. The results suggest that the magnetic structure of the Cr layer and also the magnetic hyperfine field at the "Fe probes are changed by the existence of the underlaid ferromagnetic ssFe layer due to the magnetic frustration effect at the ssFe/Cr interface.Measurements were also done for L2i-type XiYZ Heuslar alloy films and B2-type XY artificial alloy films, which were prepared by alternate deposition of monatomic or sub-atomic layers of ingredient elements. For CosMnSn Heuslar alloy films, beautiful periodic beat patterns were observed in the time spectra, which reflects the realization of samples with highly-ordered crystallographic structures. For CoSn artificial alloys, the hyperfine field was found to be small at both room temperature and low temperatures.In this way, the nuclear resonant scattering offers us some unique information on local magnetism which cannot be obtained by other experimental methods, and would also be applicable to the studies on ltral electron-spin-polarization in non-equilibrium states.