Quantum phase transition, O(3) universality class, and phase diagram of the spin-(1)/(2) Heisenberg antiferromagnet on a distorted honeycomb lattice: A tensor renormalization-group study

The spin-(1)/(2) Heisenberg antiferromagnet on the distorted honeycomb (DHC) lattice is studied by means of the tensor renormalization-group method. It is unveiled that the system has a quantum phase transition of second order between the gapped quantum dimer phase and a collinear Neel phase at the critical point of coupling ratio alpha(c) similar or equal to 0.54, where the quantum critical exponents nu similar or equal to 0.69(2) and gamma similar or equal to 1.363(8) are obtained. The quantum criticality is found to fall into the O(3) universality class. A ground-state phase diagram in the field-coupling ratio plane is proposed, where the phases such as the dimer, semiclassical Neel, and polarized phases are identified. A link between the present spin system to the boson Hubbard model on the DHC lattice is also