Correlations in Novel Quantum Materials 2022 (CNQM2022)

Bosons lost in translation

Jun 23, 2022, 4:15 PM

30m

2D5 (Max Planck Institut für Festkörperforschung)

Keynote Talk / Invited Talk Strong Correlations in Low Dimensions

Speaker

Friedrich Krien (TU Wien)

Description

Using appropriate terminology, we say more with fewer words. A useful terminology to describe two-particle electronic correlations was introduced by Hedin [1] and in the context of the spin-fermion model [2,3]. In this spirit, we show that re-expressing two-particle correlations through exchange bosons [4,5] greatly enhances the computational power of algorithms and, at the same time, gives us deeper insights into their output. Using exchange bosons, we formulate approximations that remain valid at strong coupling [6], where perturbation theory breaks down. We solve the Hubbard model on a large lattice using the parquet approach [7,8]. Finally, breaking down self-energy diagrams into bosons and their coupling to fermions provides us with an appealing explanation of the pseudogap phenomenon in cuprates [9]. The bosons, so to say, are no longer lost in translation.

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[2] P. Monthoux and D. Pines, Phys. Rev. B 47, 6069–6081 (1993).
[3] A. Abanov, A. V. Chubukov, and J. Schmalian, Advances in Physics 52, 119–218 (2003).
[4] F. Krien, A. Valli, M. Capone, Phys. Rev. B 100, 155149 (2019).
[5] F. Krien, A. Kauch, K. Held, Phys. Rev. Res. 3, 013149 (2021).
[6] V. Harkov, A.I. Lichtenstein, F. Krien, Phys. Rev. B 104, 125141 (2021).
[7] F. Krien, A.I. Lichtenstein, G. Rohringer, Phys. Rev. B 102, 235133 (2020).
[8] F. Krien, A. Kauch, Eur. Phys. J. B (2022)95:69.
[9] F. Krien, P. Worm, P. Chalupa, A. Toschi, K. Held, arXiv:2107.06529.