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1.
Using a new rheometrical technique, which makes it possible to determine both the velocity field in steady state and the strain field in the very first instants of the flow, we show that, beyond a critical deformation, typical pasty materials (a foam and a polymeric gel) turn abruptly from a viscoelastic solidlike behavior to a steady liquidlike behavior at a shear rate larger than a critical value. 相似文献
2.
We study the mean-field static solution of the Blume-Emery-Griffiths-Capel model with quenched disorder, an Ising-spin lattice gas with random magnetic interaction. The thermodynamics is worked out in the full replica symmetry breaking scheme. The model exhibits a high temperature/low density paramagnetic phase. As temperature decreases or density increases, a phase transition to a full replica symmetry breaking spin-glass phase occurs. The nature of the transition can be either of the second order or, at temperature below a given critical value, of the first order in the Ehrenfest sense, with a discontinuous jump of the order parameter, a latent heat, and coexistence of phases. 相似文献
3.
4.
Hiroshi Koibuchi 《Physica A》2011,390(23-24):4105-4113
We study an intrinsic curvature model defined on fixed-connectivity triangulated lattices enclosing a spherical core by using the canonical Monte Carlo simulation technique. We find that the model undergoes a discontinuous transition of shape transformation between the smooth state and a collapsed state even when the core radius is sufficiently large; the transition depends on . The origin of the multitude of transitions is considered to be a degeneracy of the collapsed states. We also find that the Gaussian bond potential , which is the sum of bond length squares, discontinuously changes at the transition. The discontinuity in implies a possibility of large fluctuations of the distance between lipids, or the density of lipids, in biological membranes such as giant vesicles or liposomes enclosing some materials. 相似文献
5.
The theory of first-order phase transitions in systems where the direct formation of nuclei of a new phase is inhibited for any reason, for example, because of the extremely high elastic energy, has been constructed using the example of the silicon-silicon carbide phase transition due to the chemical reaction with carbon monoxide. It has been shown that, in this case, the phase transition occurs through an intermediate state, which significantly promotes the formation of new-phase nuclei. For the silicon-silicon carbide phase transition, such an intermediate state is the “pre-carbide” state of silicon saturated with dilatation dipoles, i.e., pairs formed by a carbon atom and a silicon vacancy that are strongly attracted to each other. The model dependence of the potential energy of systems with an intermediate phase on the reaction coordinates has been investigated. The kinetics of transformation of the intermediate state into a new phase has been described. 相似文献
6.
Bianchi A Movshovich R Oeschler N Gegenwart P Steglich F Thompson JD Pagliuso PG Sarrao JL 《Physical review letters》2002,89(13):137002
The superconducting phase transition in heavy fermion CeCoIn5 (T(c)=2.3 K in zero field) becomes first order when the magnetic field H parallel [001] is greater than 4.7 T, and the transition temperature is below T0 approximately 0.31T(c). The change from second order at lower fields is reflected in strong sharpening of both specific heat and thermal expansion anomalies associated with the phase transition, a strong magnetocaloric effect, and a steplike change in the sample volume. This effect is due to Pauli limiting in a type-II superconductor, and was predicted theoretically in the mid-1960s. 相似文献
7.
Quantum phase transitions in Mott insulators do not fit easily into the Landau-Ginzburg-Wilson paradigm. A recently proposed alternative to it is the so-called deconfined quantum criticality scenario, providing a new paradigm for quantum phase transitions. In this context it has recently been proposed that a second-order phase transition would occur in a two-dimensional spin 1/2 quantum antiferromagnet in the deep easy-plane limit. A check of this conjecture is important for understanding the phase structure of Mott insulators. To this end we have performed large-scale Monte Carlo simulations on an effective gauge theory for this system, including a Berry-phase term that projects out the S=1/2 sector. The result is a first-order phase transition, thus contradicting the conjecture. 相似文献
8.
《Physics letters. [Part B]》1987,188(3):353-358
The chiral phase transition in lattice QCD has been studied for light fermions of mass ma=0.025 on lattices of size 44 and 83×4 using the hybrid algorithm. We find evidence for a first-order chiral phase transition with a large latent heat. A comparison with 103×6 data shows violations of asymptotic scaling for Tch which are similar in magnitude to those observed in the pure gauge sector. 相似文献
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Detailed Mössbauer spectra of57Fe in the iron storage protein, ferritin, in the temperature range between 250 and 280 K reveal a first-order phase transition with a thermal hysteresis loop of 7 K width. While the temperature is raised from 90 K to 271 K, Mössbauer spectra composed of a narrow line quadrupole doublet, typical for solids, are observed. Above this temperature, each spectrum is composed of the narrow line subspectrum and a broad line subspectrum whose relative intensity increases with temperature. The intensity of the narrow line subspectrum decreases by a factor of five at the critical temperature and thus shows a large increase in the mean square displacements atT up=271 K. While decreasing the temperature, the bounded diffusive motions, expressed in the spectra by the coexistence of the narrow and broad lines, survive down toT down=264 K, where again the spectral shapes and areas undergo a discontinuous jump. The narrow line subspectrum increases in intensity and the broad line subspectrum disappears. These phenomena may be understood in terms of supercooling of the water in the free channels and in the cavity of the ferritin molecule. 相似文献
11.
C. Wiele F. Haake K. Rzażewski 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(3):405-409
We solve the superradiant laser model in two limiting cases. First the stationary low-pumping regime is considered where a
first-order phase transition in the semiclassical solution occurs. This discontinuity is smeared out in the quantum regime.
Second, we solve the model in the non-stationary regime where we find a temporally periodic solution. For a certain parameter
range well-separated pulses may occur.
Received: 19 June 1998 / Accepted: 19 October 1998 相似文献
12.
The temperature dependence of the magnetic contribution to the specific heat of the anisotropic reentrant ferromagnet Li0.475Co0.05Fe1.575Ga0.9O4 with freezing temperature T
f
=80 K is investigated. It is found that for both T<T
f
and T
T
f
right up to T∼150 K the function C
m
(T) is described by the spin-wave law T
3/2, but an anomaly, exhibiting features which are characteristic for a first-order thermodynamic phase transition, is observed
in C
m
(T
3/2) at T=T
f
.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 6, 412–415 (25 September 1996) 相似文献
13.
The mechanism of the influence of an external electromagnetic field upon the temperature of the first-order phase transition in BaTiO3 is discussed in the framework of the vibronic theory of ferroelectricity. The irradiation is shown to decrease the phase transition temperature. The results are in good agreement with the experimental findings. 相似文献
14.
《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
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16.
F. Nectoux J. Jové A. Cousson M. Pagés J. Gal 《Journal of magnetism and magnetic materials》1981,24(2):L113-L116
Mössbauer effect and susceptibility studies of the tetragonal K2NpO4 compound were performed. K2NpO4 ordered magnetically at 19.5(5) K by a first-order phase transition. The ordered moment that was derived from Heff is ≈0.6μB. From the isomer shift of the Mössbauer spectra (-57(1) mm/s rel. NpAl2) it was concluded that the ground state of the Np ion in the specified compound was a 2F Kramer's doublet. 相似文献
17.
Menghini M Fasano Y de la Cruz F Banerjee SS Myasoedov Y Zeldov E van der Beek CJ Konczykowski M Tamegai T 《Physical review letters》2003,90(14):147001
We present a systematic study of the topology of the vortex solid phase in superconducting Bi2Sr2CaCu2O8 samples with low doses of columnar defects. A new state of vortex matter imposed by the presence of geometrical contours associated with the random distribution of columns is found. The results show that the first-order liquid-solid transition in this vortex matter does not require a structural symmetry change. 相似文献
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O. Post 《Russian Journal of Mathematical Physics》2007,14(4):482-492
The aim of the present paper is to introduce a first-order approach to the abstract concept of boundary triples for Laplace
operators. Our main application is the Laplace operator on a manifold with boundary; a case in which the ordinary concept
of boundary triples does not apply directly. In our first-order approach, we show that we can use the usual boundary operators
in abstract Green’s formula as well. Another motivation for the first-order approach is to give an intrinsic definition of
the Dirichlet-to-Neumann map and intrinsic norms on the corresponding boundary spaces. We also show how the first-order boundary
triples can be used to define a usual boundary triple leading to a Dirac operator.
In memoriam Vladimir A. Geyler (1943–2007) 相似文献
20.
Under certain conditions in a dusty plasma, which is a low-temperature plasma with dust grains, the strong interaction between grains can give rise to gas-liquid-solid-state phase transitions. A study is made of ordered (liquidlike and crystalline) grain structures in various kinds of dusty plasmas: a thermal plasma at atmospheric pressure, a plasma of a dc glow discharge, and a UV radiation-driven plasma. The results of experimental observations of ordered dust structures are reported, and the characteristic features of the dust structures and the conditions for their appearance are discussed. 相似文献