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MA: Fachverband Magnetismus
MA 4: Electron Theory of Magnetism and Correlations
MA 4.7: Vortrag
Montag, 17. März 2025, 11:00–11:15, H19
Tuning the order of a deconfined quantum critical point — Anika Goetz2, •Natanael C. Costa1, and Fakher Assaad2 — 1Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil — 2Institut für Theoretische Physik und Astrophysik, Universitat Würzburg, Würzburg, Germany
We consider a Su-Schrieffer-Heeger model in the assisted hopping limit where direct electron hopping is subdominant. At fixed electron-phonon coupling and in the absence of Coulomb interactions the model shows a deconfined quantum critical point between a (0,π) valence bond solid in the adiabatic limit and a quantum antiferromagnetic (AFM) at high phonon frequencies. Here we show that by adding terms to the model that reinforce the AFM phase, thereby lowering the critical phonon frequency, the quantum phase transition becomes strongly first order. Our results does not depend on the symmetry of the model. In fact by adding a Hubbard-U term to the model lowers the O(4) symmetry to SU(2), such that the DQCP we observe has the same UV symmetries as other models that account for the same quantum phase transitions.
Keywords: Deconfined quantum phase transition; Antiferromagnetism; Valence bond solid; Su-Schrieffer-Heeger model; Quantum Monte Carlo