Quantum Monte Carlo simulation of S=1/2 Heisenberg model with four spin interaction

Abstract

The spin S 1/2 Heisenberg model with four-spin interaction on the square lattice is studied by using quantum Monte Carlo method. When the four-spin interaction is dominant, the system has a VBS ground state. In this case, we find a finite-temperature second-order phase transition to the VBS state. The universality class of the transition is investigated. We estimate the critical exponents ν and η from the finite size scaling analysis and find ν 0.68(1) and η 0.55(2). © 2009 IOP Publishing Ltd.