Local order in YBa2Cu3−yCoyO6+2x studied by anomalous diffuse x-ray scattering

1994 ◽  
Vol 9 (12) ◽  
pp. 3050-3058 ◽  
Author(s):  
H. Renevier ◽  
X.B. Kan ◽  
J.P. Quintana ◽  
K.J. Zhang ◽  
J.B. Cohen
Keyword(s):  
Coherence Length ◽  
Local Order ◽  
X Ray ◽  
Intensity Measurements ◽  
X Ray Scattering ◽  
Co Concentration ◽  
Structural Coherence ◽  
Superconducting Coherence Length ◽  
The Difference ◽  
Ray Scattering

The local order in a single crystal of YBa2Cu2.53Co0.47O7.13 has been studied with anomalous diffuse x-ray scattering. (For such a Co concentration the compound is nonsuperconducting.) Intensity measurements were carried out at two energies below the Co edge. The difference data could then be expressed in terms of the local structure around a Co atom. The short-range order parameters (α's) indicate that the Co and Cu atoms are nearly randomly distributed on the Cu1 sites. The estimated size of the Co-free “domains” is 5-7 Å. The first neighbor in-plane Co-Co distances are significantly shortened, indicating that the Co atoms are displaced from their average positions. The data also show a significant decrease of the Co-O1 distance, leading to an increase of the Cu2-O1 distance. The lengthening of the Cu2-O1 distance implies a lowering of the Cu2 formal valence. The Co substitution also affects the in-plane Cu2 positions. The present study shows that the Cu-O2 structural coherence is altered on a scale smaller than the superconducting coherence length. As far as the superconductivity is concerned, the Cu2 valence remains one of the most important parameters in determining the superconducting properties of the Co-doped 123 compounds. On the other hand, there is some evidence that in order for superconductivity to occur in this and other doped cuprate compounds, the size of dopant-free regions in the basal plane may have to exceed the superconducting coherence length.

Time-Resolved X-Ray Scattering Study of Co Surface Evolution during Low-Energy Ion Irradiation

2000 ◽  
Vol 647 ◽  
Author(s):  
O. Malis ◽  
J. M. Pomeroy ◽  
R. L. Headrick ◽  
J. D. Brock
Keyword(s):  
Ion Irradiation ◽  
Local Order ◽  
Layer By Layer ◽  
Surface Evolution ◽  
Time Resolved ◽  
Ion Energy ◽  
X Ray ◽  
X Ray Scattering ◽  
Characteristic Wavelength ◽  
Ray Scattering

AbstractThe sputter-erosion of hcp Co (0001) single crystal with Ar+ ions in the 100 to 700 eV energy range was investigated using in-situ time-resolved x-ray scattering. At temperatures above 300°C the surface remains relatively smooth, erosion evolving through a layer-by-layer or step flow mechanism. In this regime the ions have a smoothening effect on the surface and the resulting roughness decreases with increasing ion energy. Below 300°C the surface develops a pattern of mounds or pits with a characteristic wavelength. The time, ion energy and temperature dependence of this wavelength were studied in detail. Epitaxial Co thin films thermally evaporated on sapphire were also sputtered through in order to synthesize self-assembled arrays of Co nanoclusters with a narrow size distribution. The degree of local order within the Co dot arrays was examined using atomic force microscopy.

Anomalous X-Ray Scattering On Sr and Sr-Eu Metaphosphate Glasses

1996 ◽  
Vol 437 ◽  
Author(s):  
M. Bionducci ◽  
C. Meneghini ◽  
G. Navarra ◽  
G. Licheri ◽  
A. Balerna ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
European Synchrotron Radiation Facility ◽  
General Purpose ◽  
Local Order ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Experiment ◽  
The Eu ◽  
Ray Scattering

AbstractThe results of an Anomalous X-ray Scattering experiment performed on Sr(PO3)2 and Eu0.1Sr0.9(PO3)2.1 glasses are presented. These are the first measurements carried out on GILDA (General purpose Italian beamLine for Diffraction and Absorption) diffractometer, located at the European Synchrotron Radiation Facility (ESRF), Grenoble. To obtain detailed information about the local order on pure and Eu-doped Sr-metaphosphate glasses both samples were investigated near the Sr K-edge (16.107 KeV), while the latter was also studied near the Eu K-edge (48.517 KeV).

Local Order in Aqueous NaCl Solutions and Pure Water:  X-ray Scattering and Molecular Dynamics Simulations Study

2006 ◽  
Vol 110 (46) ◽  
pp. 23515-23523 ◽  
Author(s):  
Salah Bouazizi ◽  
Salah Nasr ◽  
Nejmeddine Jaîdane ◽  
Marie-Claire Bellissent-Funel
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Pure Water ◽  
Local Order ◽  
X Ray ◽  
X Ray Scattering ◽  
Dynamics Simulations ◽  
Ray Scattering

Structural and Magnetic X-RAY Scattering Measurements of Epitaxial Dy thin Films

1991 ◽  
Vol 231 ◽  
Author(s):  
Michael F. Toney ◽  
David G. Wiesler ◽  
Brent D. Hermsmeier ◽  
Robin F. Farrow
Keyword(s):  
Temperature Dependence ◽  
Coherence Length ◽  
Magnetic Scattering ◽  
Temperature Hysteresis ◽  
Turn Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
Similar Temperature Dependence ◽  
Scattering Measurements ◽  
Ray Scattering

AbstractWe report structural and magnetic X-ray scattering measurements of a 2000Å thick Dy film, sandwiched by LaF3 films on a GaAs(111) substrate. The structure was grow by molecular beam epitaxy with the c-axis of the Dy parallel to the LaF3 c-axis and GaAs[111] axis. For the magnetic X-ray scattering, we used a polarization analyzer and an X-ray energy near the Dy L111 absorption edge. ∆t this energy there is a resonant enhancement in the magnetic scattering intensity, and we obtained ≃-50 counts per second in the magnetic diffraction peaks.Between 85 and 179K, bulk Dy forms a helical antiferromagnetic structure, and below 85K, it transforms into a ferromagnet. We find that the c-axis lattice constant of the Dy film has a similar temperature dependence to bulk Dy from room temperature to about 110K, but below this, the film behaves differently from bulk and is strained. The temperature dependence of the turn-angle in the helical antiferromagnetic state is similar to bulk, although a weaker dependence is observed below ∼1 10K due to magnetoelastic effects. Surprisingly, the magnetic coherence length (≃310Å) is significantly shorter than the structural coherence length (≃730Å). The transition to ferromagnetic ordering at 86K exhibits temperature hysteresis as is evident in the structural and magnetic X-ray data and in SQUID magnetometry data. We believe this hysteresis arises from a combination of the strain-energy barrier accompanying the transition and magnetic inhomogeneities in the film.

High energy x-ray scattering studies of the local order in liquid Al

2011 ◽  
Vol 135 (4) ◽  
pp. 044502 ◽  
Author(s):  
N. A. Mauro ◽  
J. C. Bendert ◽  
A. J. Vogt ◽  
J. M. Gewin ◽  
K. F. Kelton
Keyword(s):  
High Energy ◽  
Local Order ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

Isotope effects in solution small-angle X-ray scattering

1999 ◽  
Vol 32 (1) ◽  
pp. 113-114 ◽  
Author(s):  
Stephen J. Henderson
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Isotope Effects ◽  
X Rays ◽  
Light Water ◽  
X Ray ◽  
X Ray Scattering ◽  
The Difference ◽  
Ray Scattering

While the difference between using heavy and light water as solvents for small-angle neutron scattering experiments is well known, the lesser difference for the case of small-angle X-ray scattering with these same isotopes of water has, as yet, not been reported. This difference for the case of X-rays is discussed and quantified for several familiar materials: polystyrene latexes, proteins and lipids.

SCALING BETWEEN LOCALIZATION LENGTH AND TC IN DISORDERED YBa2Cu3O6.9

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3601-3604
Author(s):  
ANDREA GAUZZI ◽  
DAVOR PAVUNA
Keyword(s):  
Coherence Length ◽  
Localization Length ◽  
Charge Carriers ◽  
Superconducting Transition ◽  
Scaling Relation ◽  
X Ray Diffraction ◽  
Ginzburg Landau ◽  
X Ray ◽  
Structural Coherence ◽  
Superconducting Coherence Length

We quantitatively study the effect of growth-induced reduction of long range structural order on the superconducting transition in epitaxial YBa 2 Cu 3 O 6.9 films. The corresponding reduction of structural coherence length rc is determined from the width of X-ray diffraction rocking curves. Tc measurements in the films give evidence for the validity of the empirical scaling relation ΔTc~ rc,ab-2, where ΔTc is the disorder-induced reduction of Tc and rc,ab is the structural coherence length in the ab-plane. To explain this algebraic law we propose a simple phenomenological model based on the disorder-induced localization of the charge carriers within each ordered domain of size rc,ab. This picture enables us to precisely determine the Ginzburg-Landau superconducting coherence length in the ab-plane, and we obtain ξab=1.41±0.04 nm.

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