Abstract

Although the rise of superconductivity in the cuprate and iron pnictides is known for years, the origin of the Cooper pairing in those materials is still under debate. The high transition temperature together with the unconventional pairing symmetries support the picture of an electronic pairing glue, where the superconductivity is mediated by spin-fluctuations. In this talk we show that for the interpretation of Scanning Tunneling Microscopy (STM) data it is important to include not only elastic tunneling, but also inelastic contributions involving the tunneling of an electron from the tip to an off-shell state in the superconductor and a following transition to a state near the Fermi surface (FS) via the emission or absorption of a boson. We explicitly give expressions for the elastic and inelastic conductance. Adopting the formalism to the spin-fermion model we demonstrate that we can naturally reproduce the tunneling spectra of various unconventional superconductors and trace the occurring peak-dip-hump feature back to the opening of a spin gap in the superconducting state.