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We present bulk-sensitive hard X-ray photoelectron spectroscopy (HAXPES) data of the Ce3 d core levels and lifetime-reduced L -edge X-ray absorption spectroscopy (XAS) in the partial fluorescence yield (PFY) mode of the Ce M In 5 family with M = Co, Rh, and Ir. The HAXPES data are analyzed quantitatively with a combination of full multiplet and configuration interaction model which allows correcting for the strong plasmons in the Ce M In 5 HAXPES data, and reliable weights w n of the different f n contributions in the ground state are determined. The Ce M In 5 results are compared to HAXPES data of other heavy fermion compounds and a systematic decrease of the hybridization strength V eff from CePd 3 to CeRh 3 B 2 to CeRu 2 Si 2 is observed, while it is smallest for the three Ce M In 5 compounds. The f -occupation, however, increases in the same sequence and is close to one for the Ce M In 5 family. The PFY-XAS data confirm an identical f -occupation in the three Ce M In 5 compounds and a phenomenological fit to these PFY-XAS data combined with a configuration interaction model yields consistent results. [ABSTRACT FROM AUTHOR]

The occupancy of the 4 f n contributions in the Kondo semiconductors CeM 2 Al 10 (M = Ru, Os and Fe) has been quantitatively determined by means of bulk-sensitive hard X-ray photoelectron spectroscopy (HAXPES) on the Ce 3 d core levels. Combining a configuration interaction scheme with full multiplet calculations allowed to accurately describe the HAXPES data despite the presence of strong plasmon excitations in the spectra. The configuration interaction parameters obtained from this analysis – in particular the hybridization strength V eff and the effective f binding energy Δ f – indicate a slightly stronger exchange interaction in CeOs 2 Al 10 compared to CeRu 2 Al 10 , and a significant increase in CeFe 2 Al 10 . This shows the existence of a substantial amount of Kondo screening in these magnetically ordered systems and places the entire CeM 2 Al 10 family in the region of strong exchange interactions. [ABSTRACT FROM AUTHOR]

We have examined the lamellar structure of l-α-dimyristoylphosphatidylcholine (DMPC) bilayers and multilamellar islands grown on monocomponent and bicomponent Self-Assembled Monolayers (SAM) of octadecylsiloxane (ODS), and mixed octadecylsiloxane/dodecylsiloxane (ODS/DDS), respectively. Electron density profiles revealed by hard X-ray reflectometry measurements show significant structural differences of the DMPC films on both surfaces. While DMPC grown on uniform ODS results in the formation of unilamellar and multilamellar islands of DMPC bilayers, DMPC growth on a mixed ODS/DDS-SAM results in the formation of a (almost) closed DMPC bilayer adsorbed onto the mixed SAM. The results are explained in terms of an increased van der Waals interaction of the DMPC alkyl chains with the SAM alkyl chains of the mixed ODS/DDS SAM. Swelling in water at increasing temperatures in between 50 °C and 95 °C, results in a reduced DMPC island height due to thermal unbinding of DMPC bilayers, in case of the DMPC/ODS system. Further, characterization by nc-AFM displays the lateral shape and size of the islands as well as the discrete height distribution of the islands, which is in good agreement with the X-ray reflectometry measurements. [Copyright &y& Elsevier]

We investigated the crystal-electric field ground state of the 4f manifold in the strongly correlated topological insulator SmB6 using core-level nonresonant inelastic x-ray scattering. The directional dependence of the scattering function that arises from higher multipole transitions establishes unambiguously that the Γ8 quartet state of the Sm f5 J=5/2 configuration governs the ground-state symmetry and, hence, the topological properties of SmB6. Our findings contradict the results of density functional calculations reported so far. [ABSTRACT FROM AUTHOR]

Thin MgF 2 films are prepared using the glancing angle deposition technique in order to produce optical thin film materials with low refractive index. The optical and structural film properties are examined by spectroscopic ellipsometry and scanning electron microscope. Results show that the films are transparent with a physical thickness of 162 nm. The films present a porous and inhomogeneous microstructure in which the porosity and thus the refractive index vary inside the film. The film effective refractive index is found to decrease from 1.33 near the substrate to 1.16 at the film surface. The dependence of the refractive index on the film depth is determined using an optical model based on the effective medium approximation. In order to take into account the index gradient character of the films in the coating design of broadband antireflection coatings, the index function is discretized in a finite number of homogeneous layers. The nanoporous MgF 2 layer is combined as an outermost layer with a multilayer system prepared by magnetron sputtering to manufacture a super-broadband antireflection coating designed at a normal light incidence angle for the 400–1700 nm spectral range. Results show that the nanoporous MgF 2 coated multilayer system prepared on BK7 glass exhibits excellent antireflection properties with a residual average reflection of 0.5% in the spectral range of 400–1700 nm, owing to the low refractive index of the MgF 2 upper layer. [ABSTRACT FROM AUTHOR]

CeIrSn with a quasikagome Ce lattice in the hexagonal basal plane is a strongly valence fluctuating compound, as we confirm by hard x-ray photoelectron spectroscopy and inelastic neutron scattering, with a high Kondo temperature of TK~480 K. We report a negative in-plane thermal expansion α/T below 2 K, which passes through a broad minimum near 0.75 K. Volume and a-axis magnetostriction for B∥a are markedly negative at low fields and change sign before a sharp metamagnetic anomaly at 6 T. These behaviors are unexpected for Ce-based intermediate valence systems, which should feature positive expansivity. Rather they point towards antiferromagnetic correlations at very low temperatures. This is supported by muon spin relaxation measurements down to 0.1 K, which provide microscopic evidence for a broad distribution of internal magnetic fields. Comparison with isostructural CeRhSn suggests that these antiferromagnetic correlations emerging at T≪TK result from geometrical frustration. [ABSTRACT FROM AUTHOR]

We present linear polarization-dependent soft-x-ray absorption spectroscopy data at the Ce M4, 5 edges of Cd- and Sn-doped CeCoIn5. The 4f ground-state wave functions have been determined for their superconducting, antiferromagnetic, and paramagnetic ground states. The absence of changes in the wave functions in CeCo In1-x Cdx) 5 suggests that the 4f-conduction-electron (cf) hybridization is not affected by global Cd doping, thus supporting the interpretation of magnetic droplets nucleating long-range magnetic order. This is contrasted by changes in the wave function due to Sn substitution. Increasing Sn in CeCo ( In1-y Sny)5 compresses the 4f orbitals into the tetragonal plane of these materials, suggesting enhanced cf hybridization with the in-plane In(1) atoms and a homogeneous altering of the electronic structure. As these experiments show, the 4f wave functions are a very sensitive probe of small changes in the hybridization of 4f and conduction electrons, even conveying information about direction dependencies. [ABSTRACT FROM AUTHOR]

The crystal-field ground-state wave functions of the tetragonal, magnetically ordering Kondo lattice materials CeMAl4Si2 (M=Rh, Ir, and Pt) are determined with low-temperature linearly polarized soft-x-ray absorption spectroscopy, and estimates for the crystal-field splittings are given from the temperature evolution of the linear dichroism. Values for the dominant exchange field in the magnetically ordered phases can be obtained from fitting the influence of magnetic order on the linear dichroism. The direction of the required exchange field is ∥c for the antiferromagnetic Rh and Ir compounds, with the corresponding strength of the order of λex≈6meV (65 K). Furthermore, the presence of Kondo screening in the Rh and Ir compound is demonstrated on the basis of the absorption due to f0 in the initial state. [ABSTRACT FROM AUTHOR]