Imaging the effect of electron lattice interactions on high-T_c superconductivity in Bi₂Sr₂CaCu₂O _8+δ

One of key challenges in high-T_c superconductivity research is to identify a predominant mechanism controlling superconductivity at atomic scale. Using the spectroscopic imaging scanning tunnelling microscopy technique[1] we find a ∼91% sinusoidal variation in local energy gap Δ triggered by the crystal supermodulation revealing a strong non-random out-of-plane effect on superconductivity[2], substitutional isotope effect on the d²I/dV² spectrum reveals 6% reduction of mode energy Ω indicating the involvement of the lattice vibrations that couple strongly to the quasiparticle states of Bi₂Sr₂CaCu ₂O_8+δ [3]. We also find that the heterogeneous electronic states coupling to the lattice only occur above a certain energy which separates the spatially homogeneous and heterogeneous excitations[4].