Dynamics of electron–electron correlation and electron–phonon coupled phase progression in trilayer nickelate La4Ni3O10

Trilayer nickelates are a rich class of materials exhibiting diverse correlated phenomena, including superconductivity, density wave transitions, non-Fermi liquid behavior along with an unusual metal-to-metal transition around T* ∼ 150 K. Understanding the electronic correlations as well as lattice and charge dynamics is crucial to unravel the origin of superconductivity and other instabilities in nickelates. Our in-depth Raman measurements show that trilayer nickelate, La4Ni3O10, shows transition from electron–phonon coupled phase to the electron–electron correlated one below charge density wave transition around T* with an estimated energy gap (Δ) of ∼18–20 meV. The transition around T* is also accompanied by the emergence of zone-folded phonon modes reflecting the transition into a charge density wave phase. Phonon modes self-energy parameters show anomalous changes around T* attributed to the electron–electron correlations, and the renormalization rate of the phonon is much slower in the charge-ordered phase compared to the phase above T*. The transition around T* is marked by a suppression of the electron–phonon coupling parameter by ∼70%, a change in the quasiparticle dynamics from non-Fermi liquid to the Landau–Fermi liquid-type behavior estimated using the low-frequency (ω→0) Raman response.