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The spin-dependent surface electronic structure of ferromagnetic Fe͑110͒ is investigated experimentally and theoretically. Spin-resolved, inverse-photoemission results show a complex multipeak structure close to the Fermi level. Part of it is surface derived with an unexpected spin dependence and light-polarization dependence. The puzzling experimental findings are interpreted on the basis of a comprehensive theoretical analysis. Electronic slab calculations find surface-related features, caused by the crystal-vacuum interface, only well below the Fermi level. Calculations of the ͑inverse͒ photoemission intensities within the relativistic one-step model based on a bulk band structure, but with a realistic surface barrier, reveal an additional surface resonance around the Fermi level. Its nearly vanishing exchange splitting at ⌫ and abnormal energy dispersion behavior as a function of the wave vector parallel to the surface are in accordance with the experimental findings.

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Frequency-dependent complex conductivity measurements on the organic quasione-dimensional CDW system (Fa) 2PF6 between 10 −4 Hz and 3•10 9 Hz at temperatures ranging from 20 K to 290 K are reported. Below the temperature of the Peierls transition (TP = 182 K) the real part of the conductivity exhibits two structures, which can be attributed to two modes of the charge density wave (CDW): a temperature-dependent low-frequency relaxational mode of local oscillating deformations and a high-frequency resonant mode of the pinned CDW as a whole. The measurements indicate that the damping of the relaxational mode is dominated by free carriers in the covered temperature range. At low temperatures the dynamics of the CDW in (Fa) 2PF6 shows features characteristic of the transition into a glass-like state.

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