Resonant magnetic X-ray scattering spectra in SDW Cr -- ab initio study -----

TL;DR

This study uses ab-initio calculations to analyze resonant X-ray magnetic scattering spectra in chromium's SDW state, revealing the relationship between orbital polarization and scattering intensity.

Contribution

It provides a detailed ab-initio analysis of the resonant scattering spectra in chromium's SDW state, including the role of orbital moments and hybridization effects.

Findings

Resonant enhancement matches experimental data.

Orbital polarization fluctuates significantly with energy.

4p orbital polarization is induced by 3d orbital polarization.

Abstract

Using ab-initio band structure calculation based on the local density approximation, Cr K-edge resonant X-ray magnetic scattering spectra are analyzed in the spin density wave (SDW) state of chromium. We perform band structure calculation, assuming an ideal bcc lattice structure with the lattice constant observed at the spin-flip temperature T_{SF} and a commensurate SDW state with the propagation vector close to the observed value at T_{SF}. Taking account of the spin-orbit interaction, we obtain the orbital moment on each Cr site induced in proportion to the local spin moment, which is quite small, at most a tenth of those in nickel or iron. In spite of the tiny 3d orbital moment, the orbital polarization is found to have large fluctuations as a function of energy. We obtain the scattering intensity at the Cr K-edge on the SDW magnetic Bragg spot, which shows resonant enhancement in good agreement with the experiment. The 3d orbital polarization is found to be highly correlated with the intensity of the resonant main peak, indicating that the 4p orbital polarization is mainly induced by the 3d orbital polarization through the p-d hybridization.