arXiv subjects

A. Peter Young

Publications and source records attributed to A. Peter Young.

5 recordsLinked to original sources

arXiv2019

Percolation of Fortuin-Kasteleyn clusters for the random-bond Ising model

We apply generalisations of the Swendson-Wang and Wolff cluster algorithms, which are based on the construction of Fortuin-Kasteleyn clusters, to the three-dimensional $\pm 1$ random-bond Ising model. The behaviour of the model is determined by the temperature $T$ and the concentration $p$ of negative (anti-ferromagnetic) bonds. The ground state is ferromagnetic for $0 \le p 0$, our data suggest that the percolation transition is universal, irrespective of whether the ground state exhibits ferromagnetic or spin-glass order, and is in the universality class of standard percolation. This shows that correlations in the bond occupancy of the Fortuin-Kasteleyn clusters are irrelevant, except for $p=0$ where the clusters are tied to Ising correlations so the percolation transition is in the Ising universality class.

cond-mat.dis-nn↗

arXiv1997

Chaos in a Two-Dimensional Ising Spin Glass

We study chaos in a two dimensional Ising spin glass by finite temperature Monte Carlo simulations. We are able to detect chaos with respect to temperature changes as well as chaos with respect to changing the bonds, and find that the chaos exponents for these two cases are equal. Our value for the exponent appears to be consistent with that obtained in studies at zero temperature.

cond-mat↗

arXiv1997

A common Universality class for the three-dimensional Vortex Glass and Chiral Glass?

We present a Monte Carlo study of the d=3 gauge glass and the XY--spin glass models in the vortex representation. We investigate the critical behavior of these models by a scaling analysis of the linear resistivity and current-- voltage characteristics, both in the limits of zero and strong screening of the vortex-interactions. Without screening, both models show a glass transition at a finite temperature and, within the numerical accuracy, exhibit the same critical exponents: z approx 3.1 and nu=1.3 +- 0.3. With strong screening, the finite temperature glass transition is destroyed in both cases and the same exponent nu=1.05 +- 0.1 is found at the resulting zero temperature transition.

cond-mat.supr-con↗

arXiv1995

Quantum Spin Glasses in Finite Dimensions

The Ising spin glass model in a transverse field has a zero temperature phase transition driven solely by quantum fluctuations. This quantum phase transition occuring at a critical transverse field strength has attracted much attention recently. We report the progress that has been made via Monte Carlo simulations of the finite dimensional, short range model.

cond-mat↗

arXiv1994

Zero--Temperature Quantum Phase Transition of a Two--Dimensional Ising Spin--Glass

We study the quantum transition at $T=0$ in the spin-$\frac12$ Ising spin--glass in a transverse field in two dimensions. The world line path integral representation of this model corresponds to an effective classical system in (2+1) dimensions, which we study by Monte Carlo simulations. Values of the critical exponents are estimated by a finite-size scaling analysis. We find that the dynamical exponent, $z$, and the correlation length exponent, $ν$, are given by $z = 1.5 \pm 0.05$ and $ν= 1.0 \pm 0.1$. Both the linear and non-linear susceptibility are found to diverge at the critical point.

cond-mat↗