Unveiling the local structure of the amorphous metal [Formula: see text] combining first-principles-based simulations and modelling of EXAFS spectra.

Amorphous alloys exhibit useful properties such as the excellent soft magnetic behaviour of Fe-based metallic glasses. The detailed structure of amorphous [Formula: see text] with x = 0.07, 0.10, and 0.20 is in this work explored through a synergetic combination of atomistic simulations and experimental characterisation. Thin-film samples were investigated using X-ray diffraction and extended X-ray absorption fine structure (EXAFS), while the corresponding atomic structures were simulated using an efficient first-principles-based method called stochastic quenching (SQ). The simulated local atomic arrangements are investigated by constructing the radial- and angular-distribution functions, as well as by Voronoi tesselation. The radial distribution functions are then used to construct a model to fit simultaneously the experimental EXAFS data of multiple samples with different compositions, creating a simple yet accurate description of the atomic structures valid for any composition in the range x = 0.07 to 0.20, using a minimal number of free parameters. This approach significantly improves the accuracy of the fitted parameters and allows us to relate the compositional dependence of the amorphous structures with the magnetic properties. The proposed EXAFS fitting process can be generalised to other amorphous systems, contributing to the understanding of structure-property relationships and the development of amorphous alloys with tailored functional properties.

Enantiosensitive Bonding of Chiral Molecules on a Magnetic Substrate Investigated by Means of Electron Spectroscopies.

The adsorption of purely organic chiral molecules on ferromagnetic Co thin films is studied under ultra high vacuum conditions by means of synchrotron radiation-based electron spectroscopies, namely X-ray absorption and ultraviolet photoemission. X-ray absorption reveals that enantiomers with opposite handedness (R,R)- and (S,S)- of two different molecules adsorb with different strength on the Co surfaces and their valence band photoemission spectra also display distinctive features. In view of the recent reports describing the chiral-induced spin selectivity (CISS) effect these results lead us to consider the possibility that some enantiosensitivity may appear when bonding chiral molecules to a substrate with an initial asymmetry in the population of the different spin orientations.

Optical Coherence Tomography Angiography in Optic Nerve Drusen.

AIM: To determine the efficacy of optical coherence tomography angiography (OCT-A) in diagnosing optic nerve head flow impairment in patients with optic nerve drusen. METHODS: Patients affected by optic-nerve head drusen (ONHD) attending the Eye Clinic of the Federico II University of Naples were enrolled in this prospective case series between October 2015 and October 2016. Each patient underwent evaluation of best corrected visual acuity (BCVA), Goldman applanation tonometry, slit-lamp biomicroscopy, fundus examination, standard visual-field testing (perimetry), spectral domain (SD)-OCT and OCT-A. RESULTS: Thirteen patients (6 females and 7 males with a mean age of 22.05 ± 7.54 years) with ONHD (19 eyes) were enrolled. Mean BCVA was 0.16 ± 0.21 LogMar and mean intraocular pressure was 15.68 ± 1.66 mm Hg. The control group constituted 16 individuals (24 eyes). Both ganglion cell complex (GCC) and retinal nerve fiber layer (RNFL) parameters were lower in patients than in controls. Similarly, the flow index (U = 134, p = 0.021) and vessel density (U = 90, p = 0.001) were significantly lower in eyes affected by ONHD than in normal eyes. Visual-field parameters did not differ between the 2 groups. GCC parameters were significantly correlated with OCT-A parameters (p < 0.05). No correlation was found between RNFL and OCT-A parameters. CONCLUSIONS: Our data suggest that OCT-A could be an objective method, helpful in the analysis of flow changes in patients with ONHD.

Towards a new class of heavy ion doped magnetic semiconductors for room temperature applications.

The article presents, using Bi doped ZnO, an example of a heavy ion doped oxide semiconductor, highlighting a novel p-symmetry interaction of the electronic states to stabilize ferromagnetism. The study includes both ab initio theory and experiments, which yield clear evidence for above room temperature ferromagnetism. ZnBi(x)O(1-x) thin films are grown using the pulsed laser deposition technique. The room temperature ferromagnetism finds its origin in the holes introduced by the Bi doping and the p-p coupling between Bi and the host atoms. A sizeable magnetic moment is measured by means of x-ray magnetic circular dichroism at the O K-edge, probing directly the spin polarization of the O(2p) states. This result is in agreement with the theoretical predictions and inductive magnetometry measurements. Ab initio calculations of the electronic and magnetic structure of ZnBi(x)O(1-x) at various doping levels allow to trace the origin of the ferromagnetic character of this material. It appears, that the spin-orbit energy of the heavy ion Bi stabilizes the ferromagnetic phase. Thus, ZnBi(x)O(1-x) doped with a heavy non-ferromagnetic element, such as Bi, is a credible example of a candidate material for a new class of compounds for spintronics applications, based on the spin polarization of the p states.

Enantiospecific spin polarization of electrons photoemitted through layers of homochiral organic molecules.

Electrons photoemitted through layers of purely organic chiral molecules become strongly spin-polarized even at room temperature and for double-monolayer thicknesses. The substitution of one enantiomer for its mirror image does not revert the sign of the spin polarization, rather its direction in space. These findings might lead to the obtention of highly efficient spin filters for spintronic applications.