Zhao, BowenTakahashi, JunSandvik, Anders W.2021-07-292021-07-292020-12-18Bowen Zhao, Jun Takahashi, Anders W Sandvik. 2020. "Multicritical Deconfined Quantum Criticality and Lifshitz Point of a Helical Valence-Bond Phase.." Phys Rev Lett, Volume 125, Issue 25, pp. 257204 - ?. https://doi.org/10.1103/PhysRevLett.125.2572041079-7114https://hdl.handle.net/2144/42805The S=1/2 square-lattice J-Q model hosts a deconfined quantum phase transition between antiferromagnetic and dimerized (valence-bond solid) ground states. We here study two deformations of this model-a term projecting staggered singlets, as well as a modulation of the J terms forming alternating "staircases" of strong and weak couplings. The first deformation preserves all lattice symmetries. Using quantum Monte Carlo simulations, we show that it nevertheless introduces a second relevant field, likely by producing topological defects. The second deformation induces helical valence-bond order. Thus, we identify the deconfined quantum critical point as a multicritical Lifshitz point-the end point of the helical phase and also the end point of a line of first-order transitions. The helical-antiferromagnetic transitions form a line of generic deconfined quantum-critical points. These findings extend the scope of deconfined quantum criticality and resolve a previously inconsistent critical-exponent bound from the conformal-bootstrap method.p. 257204en-USGeneral physicsMathematical sciencesPhysical sciencesEngineeringArticle10.1103/PhysRevLett.125.2572040000-0002-5638-4619 (Sandvik, Anders W)561995