Ordering kinetics in the random-bond XY model

Variational study of the random-field XY model.

A disorder-dependent Gaussian variational approach is applied to the d-dimensional ferromagnetic XY model in a random field. The randomness yields a non extensive contribution to the variational free energy, implying a random mass term in correlation functions. The Imry-Ma low temperature result, concerning the existence (d > 4) or absence (d < 4) of long-range order is obtained in a transparen...

The XY Model on a Dynamical Random Lattice

We study the XYmodel on a lattice with fluctuating connectivity. The expectation is that at an appropriate critical point such a system corresponds to a compactified boson coupled to 2d quantum gravity. Our simulations focus, in particular, on the important topological features of the system. The results lend strong support to the two phase structure predicted on the basis of analytical calcula...

Chiral Ordering in the Four-dimensional Xy Spin Glass

Ordering kinetics in model systems with inhibited interfacial adsorption.

The Random-Bond Ising Model in 2.01 and 3 Dimensions

We consider the Ising model between 2 and 4 dimensions perturbed by quenched disorder in the strength of the interaction between nearby spins. In the interval 2 < d < 4 this disorder is a relevant perturbation that drives the system to a new fixed point of the renormalization group. At d = 2 such disorder is marginally irrelevant and can be studied using conformal perturbation theory. Combining...