Search

We demonstrate a probe of long-range antiferromagnetic (AF) order in FeRh thin films using non-resonant magnetic x-ray scattering. In particular, x-rays at energies below the Fe K-edge have been used for the observation of magnetic Bragg peaks. Due to the low efficiency of the magnetic scattering, a grazing incidence geometry was used to optimise the diffracted intensity from the thin film samples. Based on Scherrer analysis, we estimate a coherence length similar to previous reports from x-ray magnetic linear dichroism (XMLD) experiments, indicating that domain sizes are limited to 40 nm which is consistent with the grain size. The temperature dependent behaviour of the AF order shows an inverse correlation with the emergence of the ferromagnetic (FM) moment, as expected from the phase diagram. [ABSTRACT FROM AUTHOR]

Non-resonant and element specific magnetic X-ray scattering has been used to determine the orientation of Eu and Fe magnetic moments in EuFeAs iron pnictide. Experiments have been carried out on single crystal samples at the ESRF. Resonant measurements on magnetic reflections at the Eu L absorption edge indicate that the orientation of the Eu moments in the antiferromagnetic phase ( T< T=19 K) lie parallel to the crystallographic a-axis. In addition, non-resonant magnetic X-ray measurements indicate that the Fe moments are aligned along the same direction in the spin density-wave ordered phase ( T< T=190 K). The temperature dependence of the integrated intensities suggests that the Fe magnetic sublattice is barely affected by the onset of Eu ordering at T. The observation of non-zero resonant intensity on nuclear-forbidden reflections with wavevector corresponding to the Fe magnetic propagation vector at both the Eu L and As K absorption edges may be interpreted as the result of the polarization of the Eu 5d and As 4p electronic bands via hybridization with the Fe 3d states. [ABSTRACT FROM AUTHOR]

We have studied doping evolution of the temperature dependent local Cu-O displacements in the La2-xSrxCuO4 superconductor by polarized Cu K-edge extended X-ray absorption fine structure (EXAFS) measurements. While temperature dependent Debye-Waller factor of the Cu-O bonds, measuring the local Cu-O displacements, shows an anomalous increase at low temperature for the underdoped single crystals, we do not find such a dependence for the case of the overdoped system. The results, which are discussed in the light of recent angle resolved photoemission measurements, provide an evidence for some important correlation between the doping dependent electron-lattice interaction, the charge inhomogeneities and the local Cu-O displacements in the copper oxide superconductors. [ABSTRACT FROM AUTHOR]

We studied the charge-orbital ordering in the superlattice of charge-ordered insulating Pr0.5Ca0.5MnO3 and ferromagnetic metallic La0.5Sr0.5MnO3 by resonant soft x-ray diffraction (RSXD) and hard x-ray photoemission spectroscopy (HXPES). A temperature-dependent incommensurability is found in the orbital ordering by RSXD. In addition, a large hysteresis is observed that is caused by phase competition between the insulating charge ordered and metallic ferromagnetic states. No magnetic phase transitions are observed in contrast to pure Pr0.5Ca0.5MnO3 thin films, confirming the unique character of the superlattice. Mn HXPES spectra revealed a hysteresis in the metalicity, supporting the picture of phase competition. The deviation from the commensurate orbital order can be directly related to the decrease of ordered-layer thickness that leads to dimensional crossover from three-dimensional to two-dimensional orbital ordering. [ABSTRACT FROM AUTHOR]