Hidden Density-Wave Instability in the Trimer Ruthenate Ba4Ru3O10

TL;DR

This paper uncovers a hidden density-wave instability in Ba4Ru3O10, revealing complex electronic and magnetic behaviors, including nonlinear charge transport and a strongly pinned collective electronic state intertwined with antiferromagnetism.

Contribution

It demonstrates the existence of a density-wave instability in an antiferromagnetic oxide, a phenomenon not previously observed in such materials.

Findings

Detection of a phase transition at 100 K linked to electronic reconstruction

Observation of nonlinear charge transport features below 20 K

Suppression of nonlinear features with minimal Ir doping

Abstract

We report a hidden density-wave instability in the trimer-based ruthenate Ba4Ru3O10, previously regarded as a pure antiferromagnet with a phase transition at TA=100 K. This transition is manifested in lattice parameters, transport, thermodynamics, and magnetic susceptibility, yet remains remarkably insensitive to magnetic fields up to at least 14 T, indicating an electronically driven reconstruction. At much lower temperatures T*= 20 K, charge transport becomes strongly nonlinear, exhibiting distinct depinning thresholds, negative differential resistance, pronounced current- and frequency-dependence, and slow collective dynamics in the Hertz range. While each feature is characteristic of density-wave transport, their simultaneous occurrence in an antiferromagnetic oxide is unprecedented. All nonlinear signatures vanish upon only 3% Ir substitution, which preserves the crystal structure and insulating state, ruling out Joule heating or extrinsic artifacts. The wide separation between the electronic reconstruction at TA and the emergence of nonlinear dynamics at T* identifies Ba4Ru3O10 as a rare correlated system hosting a strongly pinned collective electronic state intertwined with antiferromagnetism.