This chapter describes the inversion of tunnelling data over the broader range of energy to deduce the effective phonon spectrum causing the electron pairing. The resulting coupling parameter lambda is related to the superconducting transition temperature of the sample. The inversion is based on the Eliashberg strong-coupling theory of superconductivity applied to dI/dV tunnelling density of states spectra up to the Debye energy characterizing the phonon spectrum of the superconductor. The variational method of McMillan and Rowell is the primary analytical tool in this work. Extensions of the...

This chapter describes the inversion of tunnelling data over the broader range of energy to deduce the effective phonon spectrum causing the electron pairing. The resulting coupling parameter lambda is related to the superconducting transition temperature of the sample. The inversion is based on the Eliashberg strong-coupling theory of superconductivity applied to dI/dV tunnelling density of states spectra up to the Debye energy characterizing the phonon spectrum of the superconductor. The variational method of McMillan and Rowell is the primary analytical tool in this work. Extensions of the method to include variations in the electronic density of states, anisotropy, and spin fluctuations are described here. The direct inversion method of Galkin, D'yachenko, and Svistunov is also described.