Quantum critical behavior of low-dimensional spin 1/2 Heisenberg antiferromagnets

Antonio S. T. Pires, M. E. Gouvêa

J. F. Audet, A. Fledderjohann, C. Gerhardt +3 more

Lukas Weber, Stefan Weßel

Dangling edge spins of dimerized two-dimensional spin-1 Heisenberg antiferromagnets are shown to exhibit nonordinary quantum critical correlations, akin to the scaling behavior observed in recently explored spin-1/2 systems. Based on large-scale quantum Monte Carlo simulations, we observe remarkable similarities between these two cases and examine the crossover to the fundamentally distinct behavior in the one-dimensional limit of strongly coupled edge spins. We complement our numerical analysis by a cluster mean-field theory that encompasses the qualitatively similar behavior for the spin-1 and the spin-1/2 cases and its dependence on the spatial edge spin configuration in a generic way.

Anders W. Sandvik

We present results of extensive quantum Monte Carlo simulations of the three-dimensional $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1/2$ Heisenberg antiferromagnet. Finite-size scaling of the spin stiffness and the sublattice magnetization gives the critical temperature ${T}_{\mathrm{c}}/J\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.946\ifmmode\pm\else\textpm\fi{}0.001$. The critical behavior is consistent with the classical 3D Heisenberg universality class, as expected. We discuss the general nature of the transition from quantum mechanical to classical (thermal) order parameter fluctuations at a continuous ${T}_{\mathrm{c}}>0$ phase transition.

Y. J. Kim, R. J. Birgeneau, F. C. Chou +2 more

Munehisa Matsumoto, Synge Todo, Chitoshi Yasuda +1 more