We argue that the S=1 /2 kagome antiferromagnet undergoes a quantum phase transition when the Dzyaloshinskii-Moriya coupling is increased. For D Dc the system is in a moment-free phase, and for D Dc the system develops antiferromagnetic long-range order. The quantum critical point is found to be Dc 0.1J using exact diagonalizations and finite-size scaling. This suggests that the kagome compound...

The influence of a local anisotropy of random orientation on a ferromagnetic phase transition is studied for two cases of anisotropy axis distribution. To this end a model of a random anisotropy magnet is analyzed by means of the field theoretical renormalization group approach in two loop approximation refined by a resummation of the asymptotic series. The one-loop result of Aharony indicating...

This paper deals with a three-dimensional mixture model describing materials undergoing phase transition with thermal expansion. The problem is formulated within the framework of generalized standard solids by the coupling of the momentum equilibrium equation and the flow rule with the heat transfer equation. A global solution for this thermodynamically consistent problem is obtained by using a...

We develop a general framework for reasoning about distances between transition systems with quantitative information. Taking as starting point an arbitrary distance on system traces, we show how this leads to natural definitions of a linear and a branching distance on states of such a transition system. We show that our framework generalizes and unifies a large variety of previously considered...

In a general model for square-wave bursting oscillations, we examine the fast transition between the slowly varying quiescent and active phases. In this type of bursting, the transition occurs at a saddle-node (SN) bifurcation point of the fast-variable subsystem when the slow variable is taken to be the bifurcation parameter. A critical case occurs when the SN bifurcation point is also a stead...

We develop a weakly nonlinear theory of the Kuramoto transition in an ensemble of globally coupled oscillators in presence of additional time-delayed coupling terms. We show that a linear delayed feedback not only controls the transition point, but effectively changes the nonlinear terms near the transition. A purely nonlinear delayed coupling does not effect the transition point, but can reduc...

We have studied the 3-flavor, finite temperature, QCD phase transition with staggred fermions on an Nt = 4 lattice. By studying a variety of quark masses we have located the critical point, mc, where the first order 3-flavor transition ends as lying in the region 0.32 ≤ mc ≤ 0.35 in lattice units.

In a recent Letter Hamacher, Stolze, and Wenzel [1] studied the disordered spin-1=2 antiferromagnetic XXZ chain H ˆ J X Lÿ1 iˆ1 ‰ i …S x i S x i‡1 ‡ S y i S y i‡1 † ‡ S z i S z i‡1 Š (1) with i independent identically distributed random variables uniformly distributed over the interval ‰1 ÿ W; 1 ‡ WŠ, with the parameter W controlling the strength of the disorder. The authors claim that for < 1 ...

The phase transition in the q -state Potts model with homogeneous ferromagnetic couplings is strongly first order for large q, while it is rounded in the presence of quenched disorder. Here we study this phenomenon on different two-dimensional lattices by using the fact that the partition function of the model is dominated by a single diagram of the high-temperature expansion, which is calculat...

The “crumpling” transition, between rigid and crumpled surfaces, has been object of much discussion over the past years. The common lore is that such transition should be of second order. However, some lattice versions of the rigidity term on fixed connectivity surfaces seem to suggest that the transition is of higher order instead. While some models exhibit what appear to be lattice artifacts,...