共查询到20条相似文献,搜索用时 31 毫秒
1.
We give a heuristic argument for disorder rounding of a first-order quantum phase transition into a continuous phase transition. From both weak and strong disorder analysis of the N-color quantum Ashkin-Teller model in one spatial dimension, we find that, for N > or =3, the first-order transition is rounded to a continuous transition and the physical picture is the same as the random transverse field Ising model for a limited parameter regime. The results are strikingly different from the corresponding classical problem in two dimensions where the fate of the renormalization group flows is a fixed point corresponding to N-decoupled pure Ising models. 相似文献
2.
The phase transition lines of the symmetric Ashkin-Teller model are investigated by the generalized cluster expansion method near the ising limits. It is shown that the Ising transition is universally preserved and that the first deviation from a straight phase boundary takes place in fourth order.Work performed within the research program of the Sonderforschungsbereich 125 相似文献
3.
Using the recursion method, we study the phase transitions of the
Ashkin-Teller model on the Bethe lattice, restricting ourselves to the case of ferromagnetic interactions. The isotropic Ashkin-Teller model and the
anisotropic one are respectively investigated, and exact expressions for the free energy and the magnetization are obtained. It can be found that each of the three varieties of phase diagrams, for the anisotropic Ashkin-Teller model, consists of four phases, i.e., the fully disordered paramagnetic
phase Para, the fully ordered ferromagnetic phase Ferro, and two
partially ordered ferromagnetic phases 〈σ〉and 〈σs〉, while the phase diagram, for the
isotropic Ashkin-Teller model, contains three phases, i.e., the fully
disordered paramagnetic phase Para, the fully ordered ferromagnetic phase
Baxter Phase, and the partially ordered ferromagnetic phase 〈σs〉. 相似文献
4.
We study the interfacial adsorption phenomena of the ferromagnetic five-state Potts model on the square lattice, whose transition is of weakly first-order, by using Monte Carlo simulations and finite-size scaling theory. It is shown that the net-adsorption has a finite-size effect according to the first-order phase transition even for systems much smaller than the bulk correlation length. 相似文献
5.
We present numerical results on bubble profiles, nucleation rates and time evolution for a weakly first-order quark-hadron phase transition in different expansion scenarios. We confirm the standard picture of a cosmological first-order phase transition, in which the phase transition is entirely dominated by nucleation. We also show that, even for expansion rates much lower than those expected in heavy-ion collisions nucleation is very unlikely, indicating that the main phase conversion mechanism is spinodal decomposition. 相似文献
6.
7.
In this paper we study the 3-state Potts model on the triangular lattice which has two- and three-site interactions. Using a Peierls argument we obtain a rigorous bound on the transition temperature, thereby disproving a conjecture on the location of its critical point. Low-temperature series are generated and analyzed for three particular choices of the coupling constants; a phase diagram is then drawn on the basis of these considerations. Our analysis indicates that the antiferromagnetic transition and the transition along the coexistence line are of first order, implying the existence of a multicritical point in the ferromagnetic region. Relation of the triangularq-state Potts model with other lattice-statistical problems is also discussed. In particular, an Ashkin-Teller model and the hard-hexagon lattice gas solved by Baxter emerge as special cases in appropriate limits.Supported in part by NSF grant No. DMR 78-18808. 相似文献
8.
R. Z. Levitin E. A. Popova R. M. Chtsherbov A. N. Vasiliev M. N. Popova E. P. Chukalina S. A. Klimin P. H. M. van Loosdrecht D. Fausti L. N. Bezmaternykh 《JETP Letters》2004,79(9):423-426
Cascade of phase transitions in GdFe3(BO3)4 at 156, 37, and 9 K has been detected by specific heat measurements and further studied by Raman scattering and Nd3+ spectroscopic probe method. A weakly first-order structural phase transition at 156 K is followed by a second-order antiferromagnetic ordering phase transition at 37 K and a first-order spin-reorientational phase transition at 9 K. 相似文献
9.
Within the framework of Ginzburg–Landau theory, the effect of multiplicity correlation between the dynamical multiplicity fluctuations is analyzed for a first-order phase transition from quark–gluon plasma to hadrons.Normalized factorial correlators are used to study the correlated dynamical fluctuations. A scaling behavior is found among the factorial correlators, and an approximate universal exponent, which is weakly dependent on the details of the phase transition, is obtained. 相似文献
10.
Uwe Deininghaus 《Zeitschrift für Physik B Condensed Matter》1981,45(1):71-78
Squaric acid is a layered structure with an antiferrodistortive phase transition atT
c
=373 K. Vertex and Ising models are considered, leading to the conclusion that two-dimensional squaric acid is a realization of the2d X–Y model with a cubic anisotropy, belonging to the same universality class as the Baxter or symmetrical Ashkin-Teller model. Experimental evidence is briefly discussed. 相似文献
11.
12.
We study the quantum phase transition mechanisms that arise in the interacting boson model. We show that the second-order nature of the phase transition from U(5) to O(6) may be attributed to quantum integrability, whereas all the first-order phase transitions of the model are due to level repulsion with one singular point of level crossing. We propose a model Hamiltonian with a true first-order phase transition for finite systems due to level crossings. 相似文献
13.
Abdelilah Benyoussef Lahoussine Laanait Mohamed Loulidi 《Journal of statistical physics》1994,74(5-6):1185-1193
We analyze the low-temperature phase diagram of the Ashkin-Teller model for real values of the quadratic and quartic coupling constants. 相似文献
14.
Prosper Ndizeye Felix Hontinfinde Basile Kounouhewa Smaine Bekhechi 《Central European Journal of Physics》2014,12(5):375-382
An open ferromagnetic Ashkin-Teller model with spin variables 0, ±1 is studied by standard Monte Carlo simulations on a square lattice in the presence of competing Glauber and Kawasaki dynamics. The Kawasaki dynamics simulates spin-exchange processes that continuously flow energy into the system from an external source. Our calculations reveal the presence, in the model, of tricritical points where first order and second order transition lines meet. Beyond that, several self-organized phases are detected when Kawasaki dynamics become dominant. Phase diagrams that comprise phase boundaries and stationary states have been determined in the model parameters’ space. In the case where spin-phonon interactions are incorporated in the model Hamiltonian, numerical results indicate that the paramagnetic phase is stabilized and almost all of the self-organized phases are destroyed. 相似文献
15.
C. -E. Pfister 《Journal of statistical physics》1982,29(1):113-116
For some values of the coupling constants, a proof of the existence of two phase transitions in the Ashkin-Teller model is given. Only correlation inequalities are used. 相似文献
16.
We discuss the ground state phase transition between an antiferromagnet and a valence-bond solid in a two-dimensional spin-1/2 XY model with a four-spin interaction. This transition has been proposed as a candidate for a deconfined quantum-critical point. We analyze quantum Monte Carlo data in order to accurately characterize the transition. The central question that remains to be answered is whether the transition really is continuous, or whether it is actually weakly first-order. We present the current status of both ground state and finite-temperature calculations. Based on the results, we discuss possible scenarios for the transition, none of which is consistent with deconfined quantum-criticality. However, we argue that a deconfined quantum-critical point may be located nearby in an extended parameter space.We also discuss the staggered Ising phase obtaining in the limit of strong four-spin coupling. 相似文献
17.
Hiroshi Koibuchi 《Journal of statistical physics》2007,129(4):605-621
We have studied two types of meshwork models by using the canonical Monte Carlo simulation technique. The first meshwork model
has elastic junctions, which are composed of vertices, bonds, and triangles, while the second model has rigid junctions, which
are hexagonal (or pentagonal) rigid plates. Two-dimensional elasticity is assumed only at the elastic junctions in the first
model, and no two-dimensional bending elasticity is assumed in the second model. Both of the meshworks are of spherical topology.
We find that both models undergo a first-order collapsing transition between the smooth spherical phase and the collapsed
phase. The Hausdorff dimension of the smooth phase is H≃2 in both models as expected. It is also found that H≃2 in the collapsed phase of the second model, and that H is relatively larger than 2 in the collapsed phase of the first model, but it remains in the physical bound, i.e., H<3. Moreover, the first model undergoes a discontinuous surface fluctuations transition at the same transition point as that
of the collapsing transition, while the second model undergoes a continuous transition of surface fluctuation. This indicates
that the phase structure of the meshwork model is weakly dependent on the elasticity at the junctions.
This work was supported in part by a Grant-in-Aid for Scientific Research from Japan Society for the Promotion of Science. 相似文献
18.
We calculate the Gaussian radius parameters of the pion-emitting source in high-energy heavy-ion collisions, assuming a first-order phase transition from a thermalized quark-gluon plasma (QGP) to a gas of hadrons. Such a model leads to a very long-lived dissipative hadronic rescattering phase which dominates the properties of the two-pion correlation functions. The radii are found to depend only weakly on the thermalization time tau(i), the critical temperature Tc (and thus the latent heat), and the specific entropy of the QGP. The model calculations suggest a rapid increase of R(out)/R(side) as a function of KT if a thermalized QGP were formed. 相似文献
19.
《Nuclear Physics B》2006,732(3):426-443
We found that three types of tethered surface model undergo a first-order phase transition between the smooth and the crumpled phase. The first and the third are discrete models of Helfrich, Polyakov, and Kleinert, and the second is that of Nambu and Goto. These are curvature models for biological membranes including artificial vesicles. The results obtained in this paper indicate that the first-order phase transition is universal in the sense that the order of the transition is independent of discretization of the Hamiltonian for the tethered surface model. 相似文献