Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 34: Correlated Electrons: Theory 2
TT 34.9: Vortrag
Donnerstag, 8. September 2022, 17:15–17:30, H23
Competing orders in a two-dimensional Su-Schrieffer-Heeger model — •Anika Götz1, Martin Hohenadler1,2, and Fakher Assaad1,3 — 1Institut für Theoretische Physik und Astrophysik, Universität Würzburg, 97074 Würzburg, Germany — 2Independent Researcher, Josef-Retzer-Str. 7, 81241 Munich, Germany — 3Würzburg-Dresden Cluster of Excellence ct.qmat, Am Hubland, 97074 Würzburg, Germany
We study a two-dimensional Su-Schrieffer-Heeger model of electrons coupled to Einstein phonons with auxiliary-field quantum Monte Carlo simulations. By adding a symmetry-allowed interaction, the phonons can be integrated out at the expense of imaginary-time correlations of the discrete Hubbard-Stratonovich fields. Using single spin-flip updates, we investigate the phase diagram at the O(4)-symmetric point as a function of hopping t and phonon frequency ω0. For low phonon frequencies, the C4 lattice symmetry is broken by valence bond order. Depending on t, the ordering wavevector is either (π,π) or (π,0), the latter value being accompanied by a dynamically generated π-flux in each plaquette. At larger ω0, the O(4) symmetry is spontaneously broken by long-range antiferromagnetic (AFM) order. In the limit t→ 0, the model maps onto an unconstrained Z2 gauge theory coupled to fermions which is in its confined phase for the parameters considered. Whereas the (π,0)-VBS to AFM transition is a candidate for a deconfined quantum critical point, the details of the (π,0)-VBS to (π,π)-VBS and (π,π)-VBS to AFM transitions are still under investigation.