# Local orbital degeneracy lifting as a precursor to an orbital-selective Peierls transition

## TL;DR

This paper reveals that fluctuating local structural distortions driven by electronic effects occur in transition metal compounds, significantly impacting their electronic and magnetic properties, and suggests this phenomenon may be common in similar systems.

## Contribution

It uncovers a fluctuating orbital-degeneracy-lifted state in a transition metal compound using x-ray pair distribution function analysis, highlighting a new electronic-structural interplay.

## Key findings

- Detected local symmetry lowering at high temperature in ext{cis} using x-ray PDF.
- Identified the distortions as electronically driven and fluctuating.
- Proposed the phenomenon is widespread among d-electron systems.

## Abstract

Fundamental electronic principles underlying all transition metal compounds are the symmetry and filling of the $d$-electron orbitals and the influence of this filling on structural configurations and responses. Here we use a sensitive local structural technique, x-ray atomic pair distribution function analysis, to reveal the presence of fluctuating local-structural distortions at high temperature of one such compound, \cis . We show that this hitherto overlooked fluctuating symmetry lowering is electronic in origin and will significantly modify the energy-level spectrum and electronic and magnetic properties. The explanation is a local, fluctuating, orbital-degeneracy-lifted state. The natural extension of our result would be that this phenomenon is likely to be widespread amongst diverse classes of partially filled nominally degenerate d-electron systems, with potentially broad implications for our understanding of their properties.