Direct mapping of the spin-filtered surface bands of a three-dimensional quantum spin Hall insulator

Spin-polarized band structure of the three-dimensional quantum spin Hall insulator $\rm Bi_{1-x}Sb_{x}$ (x=0.12-0.13) was fully elucidated by spin-polarized angle-resolved photoemission spectroscopy using a high-yield spin polarimeter equipped with a high-resolution electron spectrometer. Between the two time-reversal-invariant points, $\bar{\varGamma}$ and $\bar{M}$, of the (111) surface Brillouin zone, a spin-up band ($\Sigma_3$ band) was found to cross the Fermi energy only once, providing unambiguous evidence for the strong topological insulator phase. The observed spin-polarized band dispersions determine the "mirror chirality" to be -1, which agrees with the theoretical prediction based on first-principles calculations

Structure and magnetism of Fe thin films grown on Rh(001) studied by photoelectron spectroscopy

Structural and magnetic properties of Fe thin films grown epitaxially on Rh(001) are studied by spin- and angle-resolved valence-band photoemission, Fe 2p3/2 photoelectron diffraction, and x-ray magnetic circular dichroism experiments. The valence-band structure shows characteristic features of a fcc high-spin state at 4 monolayers (ML) and those of ferromagnetic bulk bcc Fe at 8 ML. The structure of the Fe film reveals fct(001) compressed along the direction perpendicular to the surface in the low-coverage region and gradually changes to distorted bcc(110) as the film thickness increases. The magnetic moments increase as a function of the film thickness and reach the same value as in bulk bcc Fe above 6 ML. The Fe films show in-plane ferromagnetism above 2 ML, and the thickness dependence of the magnetic properties is discussed in connection with the characteristic growth mode

Spin-resolved photoemission of valence-band satellites of Ni

Spin-resolved photoemission spectra of 6-, 9-, and 13-eV satellites of the ferromagnetic Ni valence band are reported. The spin polarization of the valence-band satellites and their photon energy dependence are interpreted by the multiplet configuration of 3d8 and 3d7 final states. This implies the localization of a photoexcited final state reflecting the strong electron correlation in Ni

Bonding state of the C60 molecule adsorbed on a Si(111)-(7X7) surface

We report here the measurements of the valence spectra, the C 1s and the Si 2p core-level spectra of C60 molecules adsorbed on a Si(111)-(7X7) surface, using photoelectron spectroscopy. In the valence spectra, the highest occupied molecular orbital (HOMO) of a C60 splits into two peaks at a coverage lower than 0.25 ML. The binding energies of the split peaks are 1.8 and 2.4 eV. Taking into account the polarization-dependence of the valence spectra and the binding energy of the C 1s core-level spectra, it is found that the 2.4-eV peak observed in the valence spectra is the covalent bonding state between a C60 molecule and the Si substrate, and that the 1.8-eV peak is the shifted HOMO. The Si 2p core-level spectra suggest that the bonding site is localized at the interface. We also present the energy-level scheme of the bonding state in terms of the symmetry of the HOMO

Magnetism of Fe films grown on Co(100) studied by spin-resolved Fe 3s photoemission

The magnetic properties of fcc Fe films grown on fcc Co(100) have been studied by means of spin-resolved Fe 3s core-level photoemission and characteristics of the measured spin-resolved 3s spectra for fcc Fe films have been investigated. The spin-resolved 3s spectra measured on 3.9 and 6.6 monolayer (ML) fcc Fe films are similar in spectral shape. The 3s majority-spin spectra for these fcc Fe films show weaker intensity on the high-binding-energy side than the spectrum previously reported for bulk bcc Fe. The spin-resolved 3s spectra for the fcc Fe films are analyzed by cluster model calculation consisting of four Fe atoms. In the analysis by the cluster model calculation, effects of the interatomic configuration interaction on the spin-resolved 3s spectra for fcc Fe films are discussed. Itinerancy of 3d electrons is found to be an important factor in describing the spin-resolved Fe 3s spectra. The z spin momentum estimated by the cluster calculation indicates that both the Fe films are in a high-spin ferromagnetic state near the surface. On the other hand, the spin polarization at the background in the spectrum for the 6.6 ML Fe film is much smaller than that for the 3.9 ML film. This variation of the background spin polarization indicates that the magnetic moment averaged up to deeper layers of Fe film is suppressed in the 6.6 ML film