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arXiv · 1710.04668

Deconfined Quantum Critical Point on the Triangular Lattice

Chao-Ming Jian·Alex Thomson·Alex Rasmussen·Zhen Bi·Cenke Xu
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Abstract

We first propose a topological term that captures the "intertwinement" between the standard "$\sqrt{3} \times \sqrt{3}$" antiferromagnetic order (or the so-called 120$^\circ$ state) and the "$\sqrt{12}\times \sqrt{12}$" valence solid bond (VBS) order for spin-1/2 systems on a triangular lattice. Then using a controlled renormalization group calculation, we demonstrate that there exists an unfine-tuned direct continuous deconfined quantum critical point (dQCP) between the two ordered phases mentioned above. This dQCP is described by the $N_f = 4$ quantum electrodynamics (QED) with an emergent PSU(4)=SU(4)/$Z_4$ symmetry only at the critical point. The topological term aforementioned is also naturally derived from the $N_f = 4 $ QED. We also point out that physics around this dQCP is analogous to the boundary of a $3d$ bosonic symmetry protected topological state with on-site symmetries only.

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Chao-Ming Jian, Alex Thomson, Alex Rasmussen, Zhen Bi, Cenke Xu. 2017-10-12. Deconfined Quantum Critical Point on the Triangular Lattice. https://doi.org/10.1103/physrevb.97.195115

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