Valence-selective local atomic structures on a YbInCu4 valence transition material by x-ray fluorescence holography

TL;DR

This study introduces a valence-selective x-ray fluorescence holography technique to distinguish local atomic structures around Yb2+ and Yb3+ ions in YbInCu4, revealing structural differences across the valence transition.

Contribution

The paper develops and applies a novel x-ray fluorescence holography method for valence-specific local structure analysis in a valence transition material.

Findings

Yb3+ ions have an fcc local structure.

Yb2+ ions exhibit a shifted positional structure.

The technique discriminates valence states via x-ray energy tuning.

Abstract

An experimental technique of x-ray fluorescence holography for investigating valence-selective local structures was established by employing the incident x-ray energy at a characteristic one near an x-ray absorption edge, and it was adopted to discriminate environments around Yb2+ and Yb3+ ions in a YbInCu4 valence transition material below and above the transition temperature of 42 K. The reconstructed images of the neighboring atoms around Yb3+ show a fcc structure as observed by diffraction experiments, whereas those around Yb2+ have curious cross (+) features, indicating a positional shift of the centered Yb2+ ions from the fcc lattice point.