Regensburg 2022 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 28: Correlated Electrons: Theory 1

TT 28.3: Vortrag

Donnerstag, 8. September 2022, 10:00–10:15, H23

Phase diagram of SU(N) antiferromagnet on a square lattice — •Jonas Schwab, Francesco Parisen Toldin, and Fakher F. Assaad — Institut für Theoretische Physik und Astrophysik and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, 97074 Würzburg, Germany

We investigate the ground state phase diagram of an antiferromagnetic, SU(N)-symmetric spin model on a square lattice, where the chosen irreducible representation of the su(N) algebra is described by a square Young tableaux with N/2 rows and 2S columns. Using approximation-free fermionic quantum Monte Carlo simulations for S ∈ {1/2, 1, 3/2} and even values of N in the range N ∈ [2, 20], we present a phase diagram for this model. Our results are in line with the seminal work of Read and Sachdev. For any value S, we find Néel order at small values of N, and disordered valence-bond solid (VBS) states at large N. The degeneracy of the VBS state, 4 for S=1/2 and 3/2 and 2 for S=1, close to the Néel state follows the lower bound obtained by analyzing monopole singularities in the large-S limit. In contrast in the large-N limit, the VBS ground state shows a four fold degeneracy for all values of S. In order to best image the dimerization patterns, so as to confirm the above, we use a pinning field approach.