The surface electronic structure of the narrow-gap seminconductor BiTeI exhibits a large Rashba-splitting which strongly depends on the surface termination. Here we report on a detailed investigation of the surface morphology and electronic properties of cleaved BiTeI single crystals by scanning tunneling microscopy, photoelectron spectroscopy (ARPES, XPS), electron diffraction (SPA-LEED) and density functional theory calculations. Our measurements confirm a previously reported coexistence of Te-and I-terminated surface areas

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Theresults of a numerical analysis of the effect of the hole potential on the form of the X-ray spectra of narrow band metals are given. The dependence of the spectra on the magnitude of conduction band filling as well as on the magnitude of intratomic interaction between conduction band electrons and the hole is investigated. It is shown that when the band is filled, the emission and absorption spectra vary from a form of the spectra, which occurs if the hole potential is engaged adiabatically, to a form where the interaction with the hole is not taken into account. I n the first case the spectra reflect the local impurity density, and in the second one the density of states of the unperturbed matrix. If the hole potential is strong enough, then the formation of a local level is possible. The most interesting consequence of this is the presence of two lines in core XPS. The systematic change is recorded of the intensities of these lines as the band is filled. The results of the investigation are drawn into a qualitative interpretation of the width of emission bands and of the shift of the inner lines of d-metals. Es werden Ergebnisse einer numerischen Analyse des Einflusses des Lochpotentials auf dieForm von Rontgenspektren von Schrnalbandrnetallen angegeben. Die Abhangigkeit der Spektren sowohl vom Wert der Leitungsbandbesetzung als auch von der GroDe der interatornaren Wechselwirkung zwischen Leitungsbandelektronen und Lochern wird untersucht. Es wird gezeigt, daD die Fiillung der Biinder die Emissions-und Absorptionsspektren sich von der Spektrenform, die dann auftritt, wenn das Lochpotential adiabatisch eingeht, in eine Form Bndert, wo Wechselwirkung mit dem Loch nicht beriicksichtigt wird. Im ersten Fall spiegeln die Spektren die lokale Storstellendichte, und im zweiten die Zustandsdichte der ungestorten Matrix wider. Wenn das Lochpotential stark genug ist, ist die Bildung eines lokalen Niveaus moglich. Die interessanteste Konsequep ist die Anwesenheit von zwei Linien in den Rumpf -Rontgenphotospektren. Die systematische Anderung der Intensitiiten dieser Linien, wenn das Band gefullt wird, wird aufgezeichnet. Die Ergebnisse der Untersuchung werden in eine qualitative Interpretation der Breite der Emissionsbanden und der Verschiebung der inneren Linien der d-Metalle einbezogen.

A dynamic spin-fluctuation theory that directly takes into account nonlocality of thermal spin fluctuations and their mode-mode interactions is developed. The Gaussian approximation in the theory is improved by a self-consistent renormalization of the mean field and spin susceptibility due to the third-and fourth-order terms of the free energy, respectively. This eliminates the fictitious first-order phase transition, which is typical for the Gaussian approximation, and yields a proper second-order phase transition. The effect of nonlocal spin correlations is enhanced by taking into account uniform fluctuations in the single-site mean Green function. Explicit computational formulae for basic magnetic characteristics are obtained. The extended theory is applied to the calculation of magnetic properties of Fe-Ni Invar. Almost full agreement with experiment is achieved for the magnetization, Curie temperature, and local and effective magnetic moments.