Electronic-correlation-assisted charge stripe order in a Kagome superconductor

In Sn-doped CsV₃Sb₅, we observe a sudden collapse of the long-range 2×2 charge density wave (CDW) at a critical Sn doping of x ≈ 0.07, accompanied by the emergence of a short-range charge stripe order with a modulation vector of ~1/3 along one lattice direction. Using ARPES, NMR, STM, and first-principles calculations, we show that this stripe order arises from a hidden 3×1 lattice instability in pristine CsV₃Sb₅, enhanced by in-plane chemical pressure from Sn substitution. The stripe order induces quasiparticle scattering between original and folded Kagome-d bands, suppresses the density of states at the Fermi level, and is assisted by electronic correlations. Our results demonstrate a cooperative lattice-electron mechanism for emergent orders in Kagome systems.