Search

(CaCuO2)m/(La0.7Sr0.3MnO3)n superlattices, consisting of the infinite layers cuprate CaCuO2 and the optimally doped manganite La1-xSrxMnO3, were grown by pulsed laser deposition. The transport properties are dominated by the manganite block. X-Ray absorption spectroscopy measurements show a clear evidence of an orbital reconstruction at the interface, ascribed to the hybridization between the Cu 3d3z2-r2 and the Mn 3d3z2-r2 orbitals via interface apical oxygen ions. Such a mechanism localizes holes at the interfaces, thus preventing charge transfer to the CaCuO2 block. Some charge (holes) transfer occurs toward the La0.7Sr0.3MnO3 block in strongly oxidized superlattices, contributing to the suppression of the magnetotransport properties. [ABSTRACT FROM AUTHOR]

A combination of high resolution x-ray absorption and x-ray emission spectroscopy is used to investigate electronic properties of LiCoO2 nanoparticles with various sizes down to 8 nm. We find that the nanostructuring has direct influence on the electronic structure of the title system, similar to the effect of delithiation. In particular, an abrupt reduction (increase) of the intersite (intrasite) 4p-3d hybridization is observed for nanoparticles with size smaller than 15 nm. Since the electrochemical properties are known to degrade in nanoparticles below the critical size of 15 nm, the results indicate a direct relationship between the intersite-intrasite correlations and the cathode efficiency, limiting the use of LiCoO2 nanoparticles. [ABSTRACT FROM AUTHOR]

We have developed a helium gas flow cryostat for use on synchrotron tender to hard X-ray beamlines. Very efficient sample cooling is achieved because the sample is placed directly in the cooling helium flow on a removable sample holder. The cryostat is compact and easy to operate; samples can be changed in less than 5 min at any temperature. The cryostat has a temperature range of 2.5-325 K with temperature stability better than 0.1 K. The very wide optical angle and the ability to operate in any orientation mean that the cryostat can easily be adapted for different X-ray techniques. It is already in use on different beamlines at the European Synchrotron Radiation Facility (ESRF), ALBA Synchrotron Light Facility (ALBA), and Diamond Light Source (DLS) for inelastic X-ray scattering, powder diffraction, and X-ray absorption spectroscopy. Results obtained at these beamlines are presented here.

Resonant Inelastic X-ray Scattering (RIXS) in the soft x-ray range is an element-specific energy-loss spectroscopy used to probe the electronic and magnetic excitations in strongly correlated solids. In the recent years, RIXS has been progressing very quickly in terms of energy resolution and understanding of the experimental results, but the interpretation of spectra could further improve, sometimes decisively, from a full knowledge of the polarization of incident and scattered photons. Here we present the first implementation, in a high resolution soft-RIXS spectrometer used to analyze the scattered radiation, of a device allowing the measurement of the degree of linear polarization. The system, based on a graded W/B4C multilayer mirror installed in proximity of the CCD detector, has been installed on the AXES spectrometer at the ESRF (European Synchrotron Radiation Facility); it has been fully characterized and it has been used for a demonstration experiment at the Cu L3 edge on a high-Tc superconducting cuprate. The loss in efficiency suffered by the spectrometer equipped with this test facility was a factor 17.5. We propose also a more advanced version, suitable for a routine use on the next generation of RIXS spectrometers and with an overall efficiency up to 10%.