Extraction of the self-energy and Eliashberg spectral function from angle-resolved photoemission spectroscopy – Tom van Waas

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Extraction of the self-energy and Eliashberg spectral function from angle-resolved photoemission spectroscopy

Thomas P. van Waas
Universite catholique de Louvain, Belgium

The talk will also be broadcast on Zoom:

https://hu-berlin.zoom-x.de/j/65312382601?pwd=UzGKC7rqv7ZoLkQMlDr4QhCKDJfopx.1

Abstract:

Angle-resolved photoemission spectroscopy (ARPES) is an experimental technique that provides access to the electron spectral function, defined in terms of the non-interacting dispersion and the electron self-energy. According to Matthiessen’s rule, the electron self-energy is the sum of interactions with impurities, other electrons, and phonons. From the latter contribution, the maximum-entropy method can be used to extract the Eliashberg electron-phonon coupling spectral function, which is a measure of the coupling strength of the phonon spectrum. We have embedded the maximum-entropy method in a Bayesian inference loop to fully quantify the spectral function, to be released in our novel Python package xARPES. In this talk, I showcase the features of xARPES with the 2-dimensional electron liquid on the surface of SrTiO₃ and with Li-doped graphene. In addition, I introduce a direct 2D fitting approach that offers improved numerical scaling and counteracts energy resolution issues, as demonstrated with MoTe₂.