Quantum Monte Carlo study on the phase transition for a generalized two-dimensional staggered dimerized Heisenberg model

In order to gain a deeper understanding of the quantum criticality in the explicitly staggered dimerized Heisenberg models, we study a generalized staggered dimer model named J₀-J₁-J₂ model, which corresponds to the staggered J-J' model on square lattice and honeycomb lattice when J₁/J₀ equals 1 and 0, respectively. Using quantum Monte Carlo method, we investigate all the quantum critical points of these models with J₁/J₀ changing from 0 to 1 as a function of coupling ratio α=J₂/J₀. We extract all the critical values of the coupling ratio α_c for these models, and we also obtain the critical exponents ν, β/ν, and η using different finite-size scaling ansatz. All these exponents are not in consistent with the three-dimensional Heisenberg universality class, indicating some unconventional quantum critical points in these models.