Quantum Phase Transition, O(3) Universality Class and Phase Diagram of Spin-1/2 Heisenberg Antiferromagnet on Distorted Honeycomb Lattice: A Tensor Renormalization Group Study

TL;DR

This study uses tensor renormalization group methods to analyze the quantum phase transition and phase diagram of a spin-1/2 Heisenberg antiferromagnet on a distorted honeycomb lattice, revealing an O(3) universality class transition.

Contribution

It provides the first detailed tensor renormalization group analysis of the phase diagram and critical behavior of the DHC lattice Heisenberg model, including critical exponents and universality class.

Findings

Second-order quantum phase transition at =0.54

Critical exponents =0.69 and =1.363

Identification of dimer, Neel, and polarized phases

Abstract

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} = 0.54, where the quantum critical exponents \nu = 0.69(2) and \gamma = 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, semi-classical Neel, and polarized phases are identified. A link between the present spin system to the boson Hubbard model on the DHC lattice is also discussed.