Collective Electronic Instability and Nonlinear Transport in the Trimer Ruthenate Ba₄Ru₃O₁₀

We report evidence for a collective electronic instability in the trimer lattice Ba₄Ru₃O₁₀, manifested as nonlinear transport, entropy removal, and field-independent thermodynamic anomalies near 100 K. The resistivity exhibits strong current dependence, and the I–V curves show a clear threshold for de-pinning followed by negative differential resistance, indicative of sliding of a charge-ordered condensate. The differential transport displays strong frequency dispersion, characteristic of slow collective dynamics. Heat capacity reveals a field-insensitive entropy release of 0.4 J mol⁻¹ K⁻¹, while magnetic susceptibility remains nearly Pauli-like with no Curie–Weiss component and a field-independent transition temperature at 100 K. These features collectively point to a charge density wave–like transition that partially gaps the Fermi surface with a gap of Δ ≈ 60 meV.  DFT calculations on experimentally constrained trimer structures reveal charge redistribution and enhanced electronic instability, potentially associated with CDW. Ba₄Ru₃O₁₀ thus represents a rare correlated system where orbital hybridization within Ru₃O₁₂ trimers drives a strong-coupling CDW instability distinct from conventional Peierls mechanisms.