Tensor-product state approach to spin- 12 square J1-J2 antiferromagnetic Heisenberg model: Evidence for deconfined quantum criticality

Abstract

The ground state phase of a spin-12 J1-J2 antiferromagnetic Heisenberg model on a square lattice around the maximally frustrated regime (J2∼0.5J1) has been debated for decades. Here we study this model using the cluster update algorithm for tensor-product states (TPSs). The ground state energies at finite sizes and in the thermodynamic limit (with finite size scaling) are in good agreement with exact diagonalization study. Through finite size scaling of the spin correlation function, we find the critical point J2c1=0.572(5)J1 and critical exponents ν=0.50(8),ηs=0.28(6). In the range of 0.572