Structural origin of dipole x-ray resonant scattering in the low-temperature phase ofNd0.5Sr0.5MnO3

Abstract

We have investigated the low temperature phase of a Nd 0.5 Sr 0.5 MnO 3 single crystal by x-ray resonant scattering at the Mn K-edge of the (3 0 0

Double stripe ordering inNd0.5Sr0.5MnO3determined by resonant soft x-ray scattering

“…[13][14][15][16][17] A RXS study at the Mn K edge of Nd 0.5 Sr 0.5 MnO 3 has shown that the charge segregation is much less than 1 electron, Mn 3.4+ and Mn 3.6+ for odd and even Mn, respectively. 18 This result seems to be reproduced in other half-doped manganites. [19][20][21] Simultaneous to the appearance of superlattice reflections associated to a charge modulation between both kinds of Mn atoms, forbidden reflections have also been observed in RXS experiments at the Mn K edge [13][14][15][16][17][18]22 due to the anisotropy of the atomic scattering tensor ͑so-called anisotropic tensor susceptibility or ATS reflections͒ The structure factor of those ATS reflections is given by the difference between odd-Mn atoms with different orientation of their anisotropy axis in the ab plane ͑Fig.…”

“…18 No contribution is expected from the anisotropy of the odd-Mn sublattice, as deduced from Eq. ͑3͒.…”

“…18 It is then straightforward to deduce that I Ј ͑ 0 1 2 0 ͒ = I Ј ͑ 0 1 2 0 ͒ = 0. On the other hand, the scattered intensity for → Ј and → Ј channels yields I Ј ͑0 1 2 0͒ = I Ј ͑0 1 2 0͒ = 4͑f ʈ − f Ќ ͒ 2 cos 2 sin 2 , ͑4͒ where 2 is the scattering angle and is the azimuthal angle around the scattering vector.…”

“…1͒. In a previous work, 18 we have studied the so-called OO reflection ͑ 0 5 2 0 ͒ by using RXS measurements at the Mn K edge. We demonstrated a structural origin for the ͑0 k /2 0͒ reflections owing to the different orientation of the anisotropy axis in the odd-Mn atoms following a zig-zag chain in the ab plane ͑Fig.…”

“…The intensity of these diffraction peaks has been proven to have the same azimuthal periodicity as the "so-called CO" reflections show. 18 The ATS ͑so-called OO͒ reflections tested at the Mn K edge reflect the differences on the p-symmetry projected density of empty states at the Mn site. It has been claimed that this anisotropy in the Mn p band arises from the hybridization between 3d and Mn 4p states through O 2p ones.…”