Lattice dynamics and enhanced electron–phonon coupling of itinerant magnet Fe1-xCoxSi (x ≥ 0.3): A 57Fe Mössbauer spectroscopy study

•Non-Fermi liquid behaviors and phonon softening appear at low temperatures near x  = 0.7.•Increasing cobalt content strengthens electron–electron correlations while suppressing magnetic ordering.•Electron-electron correlation facilitates electron–phonon interaction.