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V E Dmitrienko

Publications and source records attributed to V E Dmitrienko.

5 recordsLinked to original sources
PubMed2001

Chirality-induced 'forbidden' reflections in X-ray resonant scattering.

It is shown that additional Bragg reflections can appear exclusively owing to the local chirality associated with the left-right asymmetric environment of scattering atoms in non-magnetic crystals. The structure amplitude of these reflections depends on the antisymmetric part of a third-rank tensor describing the spatial dispersion effects. It enhances for resonant near-edge scattering through a mixed multipole transition, which includes a dipole-quadrupole contribution. It is shown that this mechanism works even for centrosymmetric crystals, and some realistic examples are considered in detail (alpha-Fe2O3, LiNbO3 etc.). For instance, the interference between the dipole-quadrupole and quadrupole-quadrupole terms may be responsible for the threefold symmetry of the azimuthal dependence of the hhh, h = 2n + 1, reflections observed recently in hematite.

Journal Article↗
PubMed2000

Resonant X-ray scattering in the presence of several anisotropic factors.

The general form of the X-ray susceptibility tensor near absorption edges is found when several anisotropic factors, such as the anisotropy of local atomic environment, magnetic ordering and orbital ordering, simultaneously exist in a crystal. Different phenomenological approaches are used to obtain the explicit form of the susceptibility tensor and to find the contributions from each anisotropic factor separately as well as 'combined' terms owing to their simultaneous existence. The results of the theoretical treatment are applied to the resonant diffraction by La0.5Sr1.5MnO4 below the Neel temperature, where charge and orbital ordering coexist with anisotropy of local atomic environment and magnetic ordering.

Journal Article↗