P. Segovia

Iron silicides grown on Si(100): metastable and stable phases

Abstract The growth of iron silicides on Si(100) by solid phase epitaxy has been investigated by photoelectron spectroscopies. The different iron silicide phases appearing and their stability ranges have been determined. We have found three different ranges depending on the initial Fe coverage deposited. In the case of large initial Fe coverages (above 16 ML), we have found the subsequent formation of ϵ-FeSi and β-FeSi 2 upon annealing. For initial Fe coverages below 3.4 ML, a phase of 1:1 stoichiometry is formed upon annealing, followed by the formation of a well-ordered metastable phase which we identify with FeSi 2 (CsCl). In the intermediate coverage range, while a poorly ordered phase of 1:1 stoichiometry is found for T

Noncovalent Functionalization and Charge Transfer in Antimonene

Abstract Antimonene, a novel group 15 two‐dimensional material, is functionalized with a tailormade perylene bisimide through strong van der Waals interactions. The functionalization process leads to a significant quenching of the perylene fluorescence, and surpasses that observed for either graphene or black phosphorus, thus allowing straightforward characterization of the flakes by scanning Raman microscopy. Furthermore, scanning photoelectron microscopy studies and theoretical calculations reveal a remarkable charge‐transfer behavior, being twice that of black phosphorus. Moreover, the excellent stability under environmental conditions of pristine antimonene has been tackled, thus pointing towards the spontaneous formation of a sub‐nanometric oxide passivation layer. DFT calculations revealed that the noncovalent functionalization of antimonene results in a charge‐transfer band gap of 1.1 eV.

Surface x-ray diffraction analysis using a genetic algorithm: the case of Sn/Cu(100)-

The application of genetic algorithms to the analysis of surface x-ray diffraction data is discussed and the implementation of a genetic algorithm of evolutionary type is described in detail. The structure of Sn/Cu(100)-[Formula: see text] is determined on the basis of surface x-ray diffraction data analysed using this algorithm. The results are compared to previous findings using other techniques.

Quantum well states in high-quality Cu films deposited on Co (100): A high resolution photoemission study

Quantum well (QW) states of thin Cu films deposited on Co (100) are studied using high resolution photoemission. In order to obtain a smooth Co–Cu interface, Cu films were prepared by evaporating the interfacial layer at 100 K. This allows us to obtain better defined QW features at the valence band. Furthermore, following this preparation method we are able to observe for the first time QW states at the neck of the Cu Fermi surface, which are not observable when the interfacial layer is deposited at 300 K. Using these high-quality films we also study final-state-related oscillations in the intensity of the photoemission spectra as well as the lifetime broadening of the QW states.

Metallization onset in KSi(100)−(2 × 1)

The electronic structure of single-domain KSi(100)-(2 × 1) has been probed by angle-resolved ultraviolet photoemission in order to investigate the semiconducting or metallic nature of the surface as a function of K coverage. The surface undergoes a transition from a low-coverage semiconducting phase to a high-coverage metallic phase in a narrow coverage range (width ≤0.05 ML) close to room-temperature saturation. The metallization takes place by filling of a surface band of s-pz symmetry which disappears away from \gG points. The binding energy of the K 3p core level changes during the process, reflecting the surface metallization.

Crystalline Structure and Vacancy Ordering across a Surface Phase Transition in Sn/Cu(001)

We report a surface X-ray diffraction study of the crystalline structure changes and critical behavior across the (3√2 × √2)R45° → (√2 × √2)R45° surface phase transition at 360 K for 0.5 monolayers of Sn on Cu(100). The phase transition is of the order-disorder type and is due to the disordering of the Cu atomic vacancies present in the low temperature phase. Two different atomic sites for Sn atoms, characterized by two different heights, are maintained across the surface phase transition.

Surface x-ray diffraction analysis using a genetic algorithm: the case of Sn/Cu(100)-(3\sqrt{2}\times \sqrt {2})\mathrm {R}45^{\circ }

The application of genetic algorithms to the analysis of surface x-ray diffraction data is discussed and the implementation of a genetic algorithm of evolutionary type is described in detail. The structure of Sn/Cu(100)-[Formula: see text] is determined on the basis of surface x-ray diffraction data analysed using this algorithm. The results are compared to previous findings using other techniques.

Surface x-ray diffraction analysis using a genetic algorithm: the case of Sn/Cu(100)-[Formula: see text].

The application of genetic algorithms to the analysis of surface x-ray diffraction data is discussed and the implementation of a genetic algorithm of evolutionary type is described in detail. The structure of Sn/Cu(100)-[Formula: see text] is determined on the basis of surface x-ray diffraction data analysed using this algorithm. The results are compared to previous findings using other techniques.