Effects of Pairing Potential Scattering on Fourier-Transformed Inelastic Tunneling Spectra of High-T_c Cuprate Superconductors with Bosonic Modes

摘要

Recent scanning tunneling microscopy (STM) experimentally observed strong gap inhomogeneity in Bi_2Sr_2CaCu_2O_(8+δ) (BSCCO). We argue that disorder in the pair potential underlies the gap inhomogeneity, and investigate its role in the Fourier-transformed inelastic tunneling spectra as revealed in the STM. We find that the random pair potential induces unique q-space patterns in the local density of states (LDOS) of a d-wave superconductor. We consider the effects of electron coupling to various bosonic modes and find the pattern of LDOS modulation due to coupling to the B_(1g) phonon mode to be consistent with the one observed in the inelastic electron tunnneling STM experiment in BSCCO. These results suggest strong electron-lattice coupling as an essential part of the superconducting state in high-T_c. materials.