RE L$_{3}$ X-ray absorption study of REO$_{1-x}$F$_{x}$FeAs (RE=La, Pr, Nd, Sm) oxypnictides

TL;DR

This study uses RE L3-edge XANES spectroscopy to investigate local atomic and electronic structure changes in REOFeAs oxypnictides with different rare-earth elements and fluorine doping, revealing insights into their structural and magnetic properties.

Contribution

It provides new insights into the local structural chemistry and electronic correlations in REOFeAs oxypnictides using L3-edge XANES spectroscopy, highlighting the effects of rare-earth substitution and fluorine doping.

Findings

XANES spectral weight and resonances change with F doping and rare-earth substitution.

No significant change observed across the structural phase transition.

Local structural chemistry influences superconductivity and magnetic phases.

Abstract

Rare-earth L$_{3}$-edge X-ray absorption near edge structure (XANES) spectroscopy has been used to study REOFeAs (RE=La, Pr, Nd, Sm) oxypnictides. The Nd L$_{3}$ XANES due to 2p$_{3/2}\to5\epsilon$d transition shows a substantial change in both white line (WL) spectral weight and the higher energy multiple scattering resonances with the partial substitution of O by F. A systematic change in the XANES features is seen due to varying lattice parameters with ionic radius of the rare earth. On the other hand, we hardly see any change across the structural phase transition. The results provide timely information on the local atomic correlations showing importance of local structural chemistry of the REO spacer layer and interlayer coupling in the competing superconductivity and itinerant striped magnetic phase of the oxypnictides.