Phase transitions of a quasiperiodic Josephson-junction array in magnetic fields

Structural relaxation, self-diffusion, and kinetic heterogeneity in the two-dimensional lattice Coulomb gas

We present Monte Carlo simulation results on the equilibrium relaxation dynamics in the two-dimensional lattice Coulomb gas, where finite fractions f of the lattice sites are occupied by positive charges. In the case of high-order rational values of f close to the irrational number 1-g [g identical with (square root of 5-1)/2 is the golden mean], we find that the system exhibits, for a wide range of temperatures above the first-order transition, a glassy behavior resembling the primary relaxation of supercooled liquids. Single-particle diffusion and structural relaxation show that there exists a breakdown of proportionality between the time scale of diffusion and that of structural relaxation analogous to the violation of the Stokes-Einstein relation in supercooled liquids. Suitably defined dynamic cooperativity is calculated to exhibit the characteristic nature of dynamic heterogeneity present in the system.

Intrinsic finite-size effects in the two-dimensional XY model with irrational frustration

This study investigates in detail the finite-size scaling of the two-dimensional irrationally frustrated XY model. By means of Monte Carlo simulations with entropic sampling, we examine the size dependence of the specific heat, and find remarkable deviation from the conventional finite-size scaling theory, which reveals novel intrinsic finite-size effects. Relaxation dynamics of the system is also considered, and, correspondingly, finite-size scaling of the relaxation time is examined, again giving evidence for the intrinsic finite-size effects and suggesting a zero-temperature glass transition.