Intrinsic Orbital-Dependent and Tunable C2-Symmetric Electronic States in Kagome Superconductors

The Kagome systems CsV₃Sb₅ host multiple Van Hove singularities (VHs) originating from different d orbitals, serving as a fertile platform for diverse electronic states. In the pristine sample, many anomalous behaviors occur around 35K deeply in the  2*2*2 charge density wave phase, and quasiparticle interference (QPI) studies with scanning tunneling microscopy (STM) reveal that V-orbital-derived states become incoherent above this temperature, indicating the emergence of hidden electronic states arising from other orbitals that compete with 2*2*2 bond order. To investigate the role of different orbitals and uncover the possible hidden order, we utilize STM to study undoped and Ti-doped CsV₃Sb₅. When long-range CDW is fully suppressed at a doping level of x=0.18 in CsV₃Ti_3-xSb₅, a new rotational symmetry-breaking state is found, manifested as a C₂-symmetric Fermi surface distortion mainly associated with d_x²-y²/d_xy orbitals. At a lower doping level (x=0.12), where the C₂ structural distortion of  CDW and this new C₂ distorted Fermi surface coexist, yet their principal C₂ axes are always misaligned, indicating competition between these two orders. Furthermore, statistical analysis reveals that the hidden two-fold symmetric order is unrelated to Ti dopants, and similar behavior of anisotropy k_F is observed in CsV₃Sb₅, indicating that this instability is intrinsic to Kagome layers.