Momentum, Temperature, and Doping Dependence of Photoemission Lineshape and Implications for the Nature of the Pairing Potential in High-TcSuperconducting Materials

Abstract

The anomalous momentum and temperature dependence of the spectral lineshape in data from underdoped ${\mathrm{Bi}}_2{\mathrm{Sr}}_2{\mathrm{CaCu}}_2{\mathrm{O}}_{8+\delta }$ (Bi2212) indicates that the quasiparticles are strongly coupled to collective excitations centered near $\mathbf{Q}=(\pi ,\pi )$. The doping dependence of the spectral lineshape and its correlation with the size of the superconducting gap indicate these collective excitations are related to the pairing interaction in high- $T_c$ superconductors, in analogy with phonon induced structures in tunneling spectra of low $T_c$ materials.