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SUMMARY:CM Seminar: Signature of preformed pairs in angle-resolved photoemission spectroscopy\, Janez Bonca\, University of Ljubljana
DESCRIPTION:Speaker: Janez Bonca\, University of Ljubljana \nTime: 10:00-11:00am \nLocation: BRIM 311 \nAbstract: We use density matrix renormalization group (DMRG) and variational exact diagonalization (VED) to calculate the single-electron removal spectral weight for the Hubbard-Holstein model at low electron densities. Tuning the strength of the electron-phonon coupling and of the Hubbard repulsion allows us to contrast the results for a liquid of polarons versus a liquid of bipolarons. The former shows spectral weight up to the Fermi energy\, as expected for a (uncorrelated) metal. The latter has a gap in its spectral weight\, set by the bipolaron binding energy\, although this is also a (strongly correlated) metal. This difference suggests that angle-resolved photoemission spectroscopy could be used to identify liquids of pre-formed pairs. Furthermore\, we show that the liquid of bipolarons is well approximated by an ensemble of bosons that are hard-core in momentum space\, filling the states inside the Fermi sea but otherwise non-interacting [1]. We have also generalized the calculation to allow for a finite optical phonon dispersion. The spectral function is significantly influenced by the dispersion\, particularly in systems with strong electron-phonon coupling. The sign of the curvature of the phonon band plays a crucial role in the distribution of spectral weight [2]. \nReferences \n• [1] K. Kovaˇc\, A. Nocera\, A. Damascelli\, J. Bonˇca\, and M. Berciu\, to appear in PRL\, arXiv:2409.14490 \n• [2] K. Kovaˇc and J. Bonˇca\, arXiv:2410.11537
URL:https://qmi.ubc.ca/event/cm-seminar-signature-of-preformed-pairs-in-angle-resolved-photoemission-spectroscopy-janez-bonca-university-of-ljubljana/
LOCATION:BRIM 311\, 2355 East Mall\, Vancouver\, British Columbia\, V6T 1Z4\, Canada
CATEGORIES:CM Seminar
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