Klemen Kovač (Author), Janez Bonča (Author)

Abstract

Using an efficient variational exact diagonalization method, we computed the electron removal spectral function within the framework of the Holstein-Hubbard model containing two electrons with opposite spins coupled to dispersive quantum optical phonons. We focus on how the interplay between the electron-phonon coupling and on-site Coulomb repulsion shapes the spectral function, a quantity directly relevant to angle-resolved photoemission spectroscopy (ARPES). Tuning the strengths of the electron-phonon coupling and the Hubbard interaction allows us to examine the evolution of the spectral properties of the system as it crosses over from a bound bipolaron to separate polarons. We find that phonon dispersion plays an important role: It substantially redistributes the spectral weight across the low- and the high-energy features and controls the emergence and the structure of distinct multiphonon continua. In regimes of strong electron-phonon coupling and low Coulomb repulsion, the spectral function exhibits a broad distribution reflecting bound bipolaronic states. Increasing the Coulomb repulsion weakens bipolaron binding, shifts the primary quasiparticle peak closer to polaronic behavior and confines the spectral weight near the Brillouin-zone center. Our results provide a framework for interpreting ARPES measurements in systems where phonon–mediated attraction competes with direct Coulomb repulsion.

Keywords

fizika kondenzirane snovi;kvantna fizika;optični fononi;polaroni;Holsteinov model;Hubbardov model;elektronsko-fononska sklopitev;condensed matter physics;quantum physics;optical phonons;polarons;Holstein model;Hubbard model;electron-phonon coupling;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UL FMF - Faculty of Mathematics and Physics
UDC: 538.9
COBISS: 229057027 Link will open in a new window
ISSN: 2469-9950
Views: 109
Downloads: 35
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Other data

Secondary language: Slovenian
Secondary keywords: fizika kondenzirane snovi;kvantna fizika;optični fononi;polaroni;Holsteinov model;Hubbardov model;elektronsko-fononska sklopitev;
Type (COBISS): Article
Pages: str. 115133-1-115133-12
Volume: ǂVol. ǂ111
Issue: ǂiss. ǂ11
Chronology: 2025
DOI: 10.1103/PhysRevB.111.115133
ID: 26057776