Evidence of Unconventional Universality Class in a Two-Dimensional Dimerized Quantum Heisenberg Model

Abstract

The two-dimensional $J$-$J^{\prime }$ dimerized quantum Heisenberg model is studied on the square lattice by means of (stochastic series expansion) quantum Monte Carlo simulations as a function of the coupling ratio \hbox{$\alpha =J^{\prime }/J$}. The critical point of the order-disorder quantum phase transition in the $J$-$J^{\prime }$ model is determined as \hbox{${\alpha }_{\mathrm{c}}=2.5196(2)$} by finite-size scaling for up to approximately $10000$ quantum spins. By comparing six dimerized models we show, contrary to the current belief, that the critical exponents of the $J$-$J^{\prime }$ model are not in agreement with the three-dimensional classical Heisenberg universality class. This lends support to the notion of nontrivial critical excitations at the quantum critical point.

4+ pages, 5 figures, version as published

References in corpus (4)

• "Deconfined" quantum critical points
• Quantum criticality beyond the Landau-Ginzburg-Wilson paradigm
• Bose-Einstein Condensation in Magnetic Insulators
• Generalized Directed Loop Method for Quantum Monte Carlo Simulations

Cited by in corpus (1)

• Quantum Phase Transition in a Heisenberg Antiferromagnet on a Square Lattice with Strong Plaquette Interactions