383 research outputs found
Probability-Changing Cluster Algorithm for Potts Models
We propose a new effective cluster algorithm of tuning the critical point
automatically, which is an extended version of Swendsen-Wang algorithm. We
change the probability of connecting spins of the same type, , in the process of the Monte Carlo spin update. Since we approach the
canonical ensemble asymptotically, we can use the finite-size scaling analysis
for physical quantities near the critical point. Simulating the two-dimensional
Potts models to demonstrate the validity of the algorithm, we have obtained the
critical temperatures and critical exponents which are consistent with the
exact values; the comparison has been made with the invaded cluster algorithm.Comment: 4 pages including 5 eps figures, RevTeX, to appear in Phys. Rev. Let
Magnetic properties of the spin-1/2 XXZ model on the Shastry-Sutherland lattice: Effect of long-range interactions
We study magnetic properties of the Ising-like XXZ model on the
Shastry-Sutherland lattices with long-range interactions, using the quantum
Monte Carlo method. This model shows magnetization plateau phases at one-half
and one-third of the saturation magnetization when additional couplings are
considered. We investigate the finite temperature transition to one-half and
one-third plateau phases. The obtained results suggest that the former case is
of the first order and the latter case is of the second order. We also find
that the system undergoes two successive transitions with the 2D Ising model
universality, although there is a single phase transition in the Ising limit
case. Finally, we estimate the coupling ratio to explain the magnetization
process observed in Comment: 5 pages, 6 figure
Spin-glass transition in bond-disordered Heisenberg antiferromagnets coupled with local lattice distortions on a pyrochlore lattice
Motivated by puzzling characteristics of spin-glass transitions widely
observed in pyrochlore-based frustrated materials, we investigate effects of
coupling to local lattice distortions in a bond-disordered antiferromagnet on
the pyrochlore lattice by extensive Monte Carlo simulations. We show that the
spin-glass transition temperature \TSG is largely enhanced by the
spin-lattice coupling, and furthermore, becomes almost independent of
in a wide range of the disorder strength . The critical property of the
spin glass transition is indistinguishable from that of the canonical
Heisenberg spin glass in the entire range of . These peculiar behaviors
are ascribed to a modification of the degenerate manifold from continuous to
semidiscrete one by the spin-lattice coupling.Comment: 4 pages, 3 figures, major revisions, accepted for publication in PR
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