M. M. Borisov

Absolute Intensity and Phase of the Resonant X-ray Scattering from a Germanium Crystal

The 222 and 600 reflections near the germanium absorption K edge were studied on the Kurchatov synchrotron radiation source. The energy spectrum of the 222 reflection is caused by the interference of the weak nonresonant and purely resonant contributions to the tensor atomic factor, whereas the 600 reflection is purely resonant. The energy dependence of the magnitude and phase of the resonant contribution to the scattering amplitude was determined from a change in the interference pattern. The numerical simulation of the energy spectra of reflections with the inclusion of the dipole-quadrupole and thermally induced contributions shows that the latter is dominant at room temperature.

Coexistence of Superconductivity and Ferromagnetism in the Nb(500 Å)/Fe(39 Å)/(Si(34 Å)/Mo(34 Å)) 40 /Si Nanostructure

The results of polarized neutron reflectometry investigations of the magnetic state of the Nb(500 Å) superconductor-57Fe(39 Å) ferromagnet-Si(34 Å)/Mo(34 Å)]40 superconductor nanostructure in the temperature range 2–60 K in the magnetic field with a strength of 0.5 kOe are presented. A decrease in magnetization in an iron layer for the transition of Nb(500 Å) and [Si(34 Å)/Mo(34 A)]40 layers to the superconducting state has been found.

X-ray topography of a crystal of tetragonal lysozyme

A crystal of the tetragonal modification of lysozyme grown under controlled conditions with in situ monitoring of the growth kinetics and morphology of the (110) face is studied by X-ray topography using synchrotron radiation. The choice of a diffraction reflection with optimal dispersion allows us to obtain an informative X-ray topographic image of the sample. It is found that the striations that are formed under changing supersaturation correspond to the type of zonality characteristic of crystals growing by the normal mechanism and differ from those observed in inorganic crystals growing by the layer-by-layer mechanism.

Precision structural diagnostics of layered superconductor/ferromagnet nanosystems V/Fe by reflectometry and diffuse scattering of synchrotron radiation

Layered superconducting ferromagnetic nanosystems Cu(32 nm)/V(40–80 nm)/Fe(0.5–4 nm)/MgO(001) have been investigated by reflectometry and the diffuse scattering of synchrotron radiation. The data obtained make it possible to determine the important characteristics of samples such as the layer thickness and the rms heights and lateral correlation lengths of roughness at the interfaces.

Localization of an ultrathin buried Fe layer in a multilayer structure Nb/Fe/[Mo/Si]40/SiO2 by means of X-ray standing waves

An analysis of the influence of standing waves on the angular dependencies of the fluorescent yield from an ultrathin iron layer buried inside a multilayer structure of Nb(50 nm)/Fe(3.9 nm)/[Si/Mo(6.77 nm)]40/SiO2 is presented. These angular dependencies of reflectivity and FeKα-fluorescence yield were measured at the Station for high-precision X-ray optics (HPXO) of the Kurchatov Center for Synchrotron Radiation and Nanotechnology. The measured data was analyzed with the help of our FLUO software package. As a result of the complex treatment of reflectivity and Fe fluorescent yield data, the depth profile for iron atomic density was restored.

X-ray topography of diamond crystals in quasi-forbidden reflections

The X-ray topographs of diamond crystals of different perfection degrees have been obtained using the quasiforbidden 222 reflection. It has been shown that the use of such reflections in X-ray topography makes it possible to study the distribution of the defects affecting the electron density distribution over the crystal cross section.

Magnetism in structures with ferromagnetic and superconducting layers

The influence of superconductivity on ferromagnetism in the layered Ta/V/Fe1–xVx/V/Fe1–xVx/Nb/Si structures consisting of ferromagnetic and superconducting layers is studied using polarized neutron reflection and scattering. It is experimentally shown that magnetic structures with linear sizes from 5 nm to 30 μm are formed in these layered structures at low temperatures. The magnetization of the magnetic structures is suppressed by superconductivity at temperatures below the superconducting transition temperatures in the V and Nb layers. The magnetic states of the structures are shown to undergo relaxation over a wide magnetic-field range, which is caused by changes in the states of clusters, domains, and Abrikosov vortices.

“Forbidden” reflections in resonant diffraction of synchrotron radiation in yttrium aluminum garnet Y3Al5O12

The purely resonant Bragg reflections (13, 13, 0) and (14, 0, 0) in yttrium aluminum garnet Y3Al5O12 at energies near the K absorption edge of yttrium have been studied experimentally and theoretically. The anisotropic tensor atomic factor of yttrium corresponding to dipole-dipole resonance transitions depends on three independent parameters changing with energy. The intensities of the reflections (14, 0, 0) and (13, 13, 0) are shown to depend on the parameter difference f1(E) − f2(E) and the parameter f3(E), respectively, which are attributable to distortions of the wave functions of the excited atoms and change greatly with photon energy E. Studying various reflections has allowed one to determine the various components of the tensor atomic factor and to compare them with the results of numerical calculations.

Resonant diffraction of synchrotron radiation in rubidium dihydrophosphate crystals

AbstractPurely resonant Bragg reflections 006, 5