Revealing the Orbital Origins of Exotic Electronic States with Ti Substitution in Kagome Superconductor CsV_{3}Sb_{5}.

Abstract

The multiband kagome superconductor CsV_{3}Sb_{5} 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 CsV_{3}Sb_{5}, 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 CsV_{3}Sb_{5}, whereas the out-of-plane component disappears with doping-induced suppression of charge density wave and global electronic nematicity. In addition, the Sb p_{z} orbital plays an important role in both the pseudogap and superconducting states in CsV_{3}Sb_{5}. 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.