In quantum materials, many emergent phenomena appear when correlation is at play. A key issue in strongly correlated materials is to understand the multiple orders, interactions and the relationship between them. In this talk, I will present our recent results on two model systems-the high-Tc cuprate superconductor and its 5d-electron counterpart (iridate). In cuprates, various intertwined orders and interactions have been revealed. A possible positive-feedback loop has been proposed between the pseudogap, electron-phonon coupling and superconductivity. In iridates, the spectroscopic evidence for electron-boson coupling has been observed in the electron-doped Sr₂IrO₄ for the first time. This observation, when combined with the earlier reports of pseudogap and d-wave instability, establishes Sr₂IrO₄ as a non-cuprate platform to study these phenomena. Finally, I will briefly mention a recent observation of a sharp transition from incoherent to coherent quasiparticles in the normal state of cuprates and discuss its possible implication for iridates.