Electronic structures, magnetic, and transport properties of organometallic sandwich molecular wire (SMW) constructed with altering europium (Eu) atoms and cyclooctatetraene (COT) rings have been studied by spin-polarized first-principles calculations and nonequilibrium Green’s function method. The one-dimensional Eu-COT SMW is predicted to be a ferromagnetic semiconductor. The calculated average magnetic moment per Eu atom is about 7μB. The total magnetic moment (TMM) of Eun(COT)n+1(n=1–4) sandwich clusters increases linearly with the number of Eu atoms and the linear relation TMM=7n-2 holds, which agrees nicely with experimental observations. The spin transportation calculations show that Eu-COT clusters coupled to gold electrodes are nearly perfect spin filters. In addition, we find that this large transmission spin polarization is very robust regardless of the contact configuration of the junctions, which is very important for the future molecular spintronics.

The recently built electron-energy-loss spectrometer (EELS) (typical FWHM 60 meV) was employed to measure the EELS spectra of argon in the discrete and autoionization resonance regions at a 2.5-keV impact energy and a mean scattering angle of O'. Relative differential optical oscillator strength spectra were established by multiplying the EELS spectra by the known Bethe-Born conversion factor of the spectrometer, and were normalized at a single point in the smooth continuum using the absolute values reported by Chan et al. [Phys. Rev. A 46, 149 (1992)]. The absolute oscillator strengths corresponding to these energy regions are reported and compared with previously published experimental and theoretical values. The values of parameters q, p, E", and I for autoionization resonances involving states 3s3p np 'P, (n =4, 5, and 6) have been determined.

We investigate the spin transport properties of iron-phthalocyanine (FePc) molecule sandwiched between two N-doped graphene nanoribbons (GNRs) based on the density functional theory and nonequilibrium Green's function methods. Our calculated results clearly reveal that the FePc molecular junction has high spin-filter efficiency as well as negative differential resistance (NDR). The zero-bias conductance through FePc molecule is dominated by the spin-down electrons, and the observed NDR originates from the bias-dependent effective coupling between the FePc molecular orbitals and the narrow density of states of electrodes. The remarkable high spin-filter efficiency and NDR are robust regardless of the edge shape and the width of GNRs, and the N-doping site in GNRs. These predictions indicate that FePc junction holds great promise in molecular electronics and spintronics applications.

Generalized oscillator strengths for the vibronic bands of A 1 ⌸, B 1 ⌺ ϩ , C 1 ⌺ ϩ , and E 1 ⌸ have been determined by an angle-resolved electron energy loss spectroscopy at an incident electron energy of 1500 eV and in an angular range of 0.5°-6.0°. The corresponding absolute optical oscillator strengths obtained by extrapolating the generalized oscillator strengths to K 2 ϭ0 are also reported. The present results have been compared with previous work, and some differences between them have been explained. The experimental generalized oscillator strengths for vЈϭ0 -8 of A 1 ⌸, vЈϭ0 -1 of B 1 ⌺ ϩ , C 1 ⌺ ϩ , and E 1 ⌸ are reported.