SPIN-RESOLVED X-RAY PHOTOEMISSION-STUDIES OF FERROMAGNETIC METALS

Recent spin-resolved x-ray photoelectron spectroscopy (SRXPS) studies of ferromagnetic metals are reviewed. SRXPS studies of metallic Fe, Co , (CoFe4Ni1B14Si15)-Fe-66, and Ni demonstrate that core-level photoemi ssion, and the itinerant electron response to core-hole creation, are highly spin-dependent. The exchange splitting of the Fe 2p(3/2) level is found to be 0.48 +/- 0.05 eV. Lifetime broadening results for the F e 2p(3/2) N up arrow (majority spin) and N down arrow (minority spin) components indicate conservation of spin in core-hole filling processe s involving the valence band. SRXPS study of the Fe 2p(3/2) peak asymm etry alpha reveals a dependence of electron-hole excitation on the spi n of the core hole. Spin analysis of the Fe 3s XPS line shape shows it to be a three-component spectrum, rather than the two-component line shape assumed previously. A photon energy dependence of one of the Fe 3s components explains disagreement among previous Fe 3s XPS results. Comparisons of SRXPS from Co metal and Co66Fe4Ni1B14Si15 directly demo nstrate the effect of a reduced atomic magnetic moment on the spin dep endence of core-level XPS. The behavior of lifetime broadenings for th e N up arrow and N down arrow Co 2p(3/2) components show that the redu ced Co magnetic moment found in the Co66Fe4Ni1B14Si15 amorphous glass is due to the transfer of up arrow-spin valence electron density to th e down arrow-spin valence band upon glass formation. SRXPS also allows investigation of spin-dependent core-hole screening processes and sat ellite production, as demonstrated in SRXPS studies of ferromagnetic N i. Future directions of SRXPS are also explored. (C) 1996 American Vac uum Society.