Revealing the Orbital Origins of Exotic Electronic States with Ti Substitution in Kagome Superconductor CsV3Sb5

The multiband kagome superconductor CsV3Sb5 exhibits complex orbital textures on the Fermi surface, making the orbital origins of its cascade of correlated electronic states and superconductivity a major scientific puzzle. Chemical doping of the kagome plane can simultaneously tune the exotic states and the Fermi-surface orbital texture and thus offers a unique opportunity to correlate the given states with specific orbitals. In this Letter, by substituting V atoms with Ti in the kagome superconductor CsV3Sb5, we reveal the orbital origin of a cascade of its correlated electronic states through the orbital-resolved quasiparticle interference. We analyze the quasiparticle interference changes associated with different orbitals, aided by first-principles calculations. We have observed that the in-plane and out-of-plane vanadium 3d orbitals cooperate to form unidirectional coherent states in pristine CsV3Sb5, whereas the out-of-plane component disappears with doping-induced suppression of charge density wave and global electronic nematicity. In addition, the Sb pz orbital plays an important role in both the pseudogap and superconducting states in CsV3Sb5. Our findings offer new insights into multiorbital physics in quantum materials that are generally manifested with intriguing correlations between atomic orbitals and symmetry-encoded correlated electronic states.