Dual Orbital Degeneracy Lifting in a Strongly Correlated Electron System

TL;DR

This study investigates the local structural changes in NaTiSi$_{2}$O$_{6}$ across its orbital-assisted Peierls transition, revealing a persistent orbital degeneracy lifted state at high temperatures in a strongly correlated electron system.

Contribution

It uncovers the existence of a dual orbital degeneracy lifted state that persists well above the transition temperature, extending ODL phenomenology to strongly correlated materials.

Findings

Local symmetry breaking occurs above the transition temperature.

A short-range orbital degeneracy lifted state persists up to 490 K.

The ODL state spans approximately 6 Ti sites along zigzag chains.

Abstract

The local structure of NaTiSi$_{2}$O$_{6}$ is examined across its Ti-dimerization orbital-assisted Peierls transition at 210 K. An atomic pair distribution function approach evidences local symmetry breaking preexisting far above the transition. The analysis unravels that on warming the dimers evolve into a short range orbital degeneracy lifted (ODL) state of dual orbital character, persisting up to at least 490 K. The ODL state is correlated over the length scale spanning $\sim$6 sites of the Ti zigzag chains. Results imply that the ODL phenomenology extends to strongly correlated electron systems.