HiSORセミナー
Bayesian inference study of electron-phonon interaction from angle-resolved photoemission spectroscopy
日時 2022年10月27日 （木） 16：00～17：00
場所 オンライン(Zoom形式)
講師 Thomas Petrus van Waas
(Université catholique de Louvain)
In many metals at sufficiently low temperatures, the interaction of electrons with bosons, impurities, and other electrons gives rise to a system of interacting Landau quasiparticles known as a Fermi liquid [1]. These interactions modify the electron spectral function [2] through a complex self-energy consisting of the boson, electron, and impurity contributions [3]. The spectral function is the central quantity investigated in angle-resolved photoemission spectroscopy (ARPES) [2], where predominantly the electron-phonon interaction appears as a photoemission kink [4]. Furthermore, the phonon contribution can be quantified in terms of the so-called Eliashberg function [5], describing the interaction effects of a phonon with a given frequency.
In this seminar, I will first explain how to obtain the self-energy from ARPES band maps, which requires incorporating the experimental resolution and photoemission matrix elements [6] in the analysis. Second, I will demonstrate the challenges in accurate quantification of the Eliashberg function. Employing the Maximum Entropy Method (MEM) [7] ensures that the Eliashberg function is everywhere non-negative and consequently physically meaningful. By embedding the MEM inside of a Bayesian inference framework, we have been able to quantify additional physical parameters of interest, such as the magnitudes of the electron interaction contributions and the electron bare band mass. Our results allow for extracting the Eliashberg function from ARPES in a reliable and semi-automated way. Thus, we pave the way towards quantitative comparison with electron-phonon interaction as obtained from first principles [4] in an effort that we have coined "ARPES in silico".
[1] H. Bruus & K. Flensberg, Oxford University Press (2004)
[2] A. Damascelli, Phys. Scr. T109, 61 (2004)
[3] A. Matthiessen & C. Vogt, Philos. Trans. R. Soc. 154, 167 (1863)
[4] S. Poncé et al., Comp. Phys. Commun. 209, 116 (2016)
[5] G. Grimvall, North-Holland Publishing Company, Amsterdam (1984)
[6] S. Moser, J. Electron Spectros. Relat. Phenomena 214, 29 (2017)
[7] M. Jarrell & J.E. Gubernatis, Phys. Rep. 269, 63 (1996)
問合せ先 出田真一郎、島田賢也（放射光科学研究センター）
