Francisco H. Kim | Searcharxiv

arXiv2019

Self-conjugate representation SU(3) chains

It was recently argued that SU(3) chains in the $p$-box symmetric irreducible representation (irrep) exhibit a "Haldane gap" when $p$ is a multiple of 3 and are otherwise gapless [Nucl. Phys. B $\boldsymbol{924}$, 508 (2017)]. We extend this argument to the self-conjugate irreps of SU(3) with $p$ columns of length 2 and $p$ columns of length 1 in the Young tableau ($p=1$ corresponding to the adjoint irrep), arguing that they are always gapped but have spontaneously broken parity symmetry for $p$ odd but not even.

cond-mat.str-el↗

arXiv2019

Dimensional crossover in the SU(4) Heisenberg model in the six-dimensional antisymmetric self-conjugate representation revealed by quantum Monte Carlo and linear flavor-wave theory

Using linear flavor-wave theory (LFWT) and auxiliary field quantum Monte Carlo (QMC), we investigate the properties of the SU(4) Heisenberg model on the anisotropic square lattice in the fully antisymmetric six-dimensional irreducible representation, a model that describes interacting fermions with four flavors at half-filling. Thanks to the calculations on very large systems, we have been able to convincingly demonstrate that QMC results are consistent with a small but finite antiferromagnetic moment at the isotropic point, in qualitative agreement with LFWT obtained earlier [F. H. Kim {\it{et al.}}, Phys. Rev. B {\bf 96}, 205142 (2017)], and in quantitative agreement with results obtained previously on the Hubbard model [D. Wang {\it{et al.}}, Phys. Rev. Lett. {\bf 112}, 156403 (2014)] after extrapolation to infinite $U/t$. The presence of a long-range antiferromagnetic order has been further confirmed by showing that a phase transition takes place into a valence-bond solid (VBS) phase not too far from the isotropic point when reducing the coupling constant along one direction on the way to decoupled chains.

cond-mat.str-el↗