scholarly journals Holographic approach of the spinodal instability to criticality

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Maximilian Attems
Keyword(s):  
Surface Tension ◽  
Critical Point ◽  
Single Phase ◽  
Transverse Pressure ◽  
First Order Phase Transition ◽  
Holographic Approach ◽  
Spinodal Instability ◽  
First Order Phase ◽  
Gauge Gravity ◽  
Gravity Duality

Abstract A smoking gun signature for a first-order phase transition with negative speed of sound squared $$ {c}_s^2 $$ c s 2 is the occurrence of a spinodal instability. In the gauge/gravity duality it corresponds to a Gregory-Laflamme type instability, which can be numerically simulated as the evolution of unstable planar black branes. Making use of holography its dynamics is studied far from and near a critical point with the following results. Near a critical point the interface between cold and hot stable phases, given by its width and surface tension, is found to feature a wider phase separation and a smaller surface tension. Far away from a critical point the formation time of the spinodal instability is reduced. Across softer and harder phase transitions, it is demonstrated that mergers of equilibrated peaks and unstable plateaux lead to the preferred final single phase separated solution. Finally, a new atypical setup with dissipation of a peak into a plateau is discovered. In order to distinguish the inhomogeneous states I propose a new criterium based on the maximum of the transverse pressure at the interface which encodes phase-mixed peaks versus fully phase separated plateaux.

Structure and Dielectric Properties of Ce and Ca Co-Doped BaTiO3 Ceramics

2016 ◽  
Vol 680 ◽  
pp. 184-188 ◽  
Author(s):  
Da Yong Lu ◽  
Dan Dan Han ◽  
Qiao Li Liu ◽  
Yan Dong Wang ◽  
Xiu Yun Sun
Keyword(s):  
Phase Transition ◽  
Dielectric Properties ◽  
Single Phase ◽  
Ceramic Structure ◽  
Co Doping ◽  
Valence States ◽  
First Order Phase Transition ◽  
First Order Phase ◽  
Diffuse Phase ◽  
Co Doped

Structure and dielectric properties of 5 % Ce and Ca co-doped BaTiO3 ceramics were investigated. The site occupations and valence states were studied using XRD, Raman spectroscopy, SEM, EPR and dielectric measurements. The Ba/Ti ratio has dramatic effects on ceramic structure and properties. Two single-phase ceramics with Ba/Ti = 1 and 0.937 have tetragonal and cubic structure, showing diffuse phase transition and first-order phase transition behaviors, respectively. The former exhibit the site occupations of mixed Ca2+/Ce3+ at Ba sites and Ca2+/Ce4+ at Ti sites. Ce ions have priority over Ca2+ ions in entering Ti sites as Ce4+ when co-doping in BaTiO3, which will impede Ca2+ ions to be incorporated completely into Ti sites.

What favors and disfavors the critical point of QCD?

Open Physics ◽  
2012 ◽  
Vol 10 (6) ◽  
Author(s):  
Kenji Fukushima
Keyword(s):  
Phase Transition ◽  
Critical Point ◽  
Chemical Potential ◽  
Qcd Critical Point ◽  
First Order Phase Transition ◽  
Model Predictions ◽  
Model Independent ◽  
Model Setup ◽  
Effective Models ◽  
First Order Phase

AbstractResults from chiral effective models suggest the existence of the so-called QCD critical point. These model predictions are highly dependent on the model setup and there is no universal argument for its existence and location. I discuss why a first-order phase transition is generally favored in models at low temperature T and high chemical potential µ, which will explain why the model results are unreliable about the critical point. I propose a useful way to reinterpret the model results as a liquid-gas-type phase transition like that of nuclear matter. This picture provides us with a fairly model-independent description of the QCD critical point not relying on detailed phase structures.

THE SPECTRUM OF THE $\mathcal{T}$-MATRIX AND THE SURFACE TENSION IN THE SU(3) GAUGE THEORY

1992 ◽  
Vol 03 (05) ◽  
pp. 947-960 ◽  
Author(s):  
T. TRAPPENBERG
Keyword(s):  
Phase Transition ◽  
Surface Tension ◽  
Gauge Theory ◽  
Finite Size ◽  
Temperature Phase ◽  
Finite Size Effects ◽  
First Order ◽  
First Order Phase Transition ◽  
Temperature Phase Transition ◽  
First Order Phase

The transfer matrix method to describe finite size effects due to tunneling are worked out for Z(2)- and Z(3)-symmetric models. We used this method to extract the surface tension σ in the SU(3) gauge theory at the finite temperature phase transition on lattices with an extent T=2 in the euclidean time direction. We also discuss if the confined phase completely wets the deconfined phase at this first order phase transition.

scholarly journals Locating the QCD Critical Point Using Holographic Black Holes

Proceedings ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 40
Author(s):  
Israel Portillo
Keyword(s):  
Black Holes ◽  
Critical Point ◽  
Chemical Potential ◽  
Transition Line ◽  
Qcd Critical Point ◽  
First Order ◽  
Qcd Phase Diagram ◽  
Baryonic Chemical Potential ◽  
First Order Phase Transition ◽  
First Order Phase

It has been shown that holographic black holes, constructed to mimic the equation of state of QCD computed on the lattice at finite temperature and zero density, display critical behavior at large baryonic chemical potential. In this proceedings, we discuss the mapping of holographic black holes into the QCD phase diagram and the emergence of the critical point and the first order phase transition line.

scholarly journals Impurity effect on hysteric magnetoconductance: holographic approach

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Kyung Kiu Kim ◽  
Keun-Young Kim ◽  
Sang-Jin Sin ◽  
Yunseok Seo
Keyword(s):  
Time Reversal ◽  
Spontaneous Magnetization ◽  
Surface States ◽  
Weak Localization ◽  
Impurity Effect ◽  
Dimensional System ◽  
Holographic Approach ◽  
Gauge Gravity ◽  
Similar Phase ◽  
Gravity Duality

Abstract In this paper we study a hysteric phase transition from weak localization phase to hysteric magnetoconductance phase using gauge/gravity duality. This hysteric phase is triggered by a spontaneous magnetization related to ℤ2 symmetry and time reversal symmetry in a 2+1 dimensional system with momentum relaxation. We derive thermoelectric conductivity formulas describing non-hysteric and hysteric phases. At low temperatures, this magnetoconductance shows similar phase transitions of topological insulator surface states. We also obtain hysteresis curves of Seebeck coefficient and Nernst signal. It turns out that our impurity parameter changes magnetic properties of the dual system. This is justified by showing increasing susceptibility and the spontaneous magnetization with increasing impurity parameter.

scholarly journals Crossing a large-N phase transition at finite volume

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Yago Bea ◽  
Oscar J. C. Dias ◽  
Thanasis Giannakopoulos ◽  
David Mateos ◽  
Mikel Sanchez-Garitaonandia ◽  
...  
Keyword(s):  
Phase Transition ◽  
Finite Volume ◽  
Linear Time ◽  
Essential Feature ◽  
Stable States ◽  
Strongly Coupled ◽  
Large N ◽  
First Order Phase Transition ◽  
Spinodal Instability ◽  
First Order Phase

Abstract The existence of phase-separated states is an essential feature of infinite-volume systems with a thermal, first-order phase transition. At energies between those at which the phase transition takes place, equilibrium homogeneous states are either metastable or suffer from a spinodal instability. In this range the stable states are inhomogeneous, phase-separated states. We use holography to investigate how this picture is modified at finite volume in a strongly coupled, four-dimensional gauge theory. We work in the planar limit, N → ∞, which ensures that we remain in the thermodynamic limit. We uncover a rich set of inhomogeneous states dual to lumpy black branes on the gravity side, as well as first- and second-order phase transitions between them. We establish their local (in)stability properties and show that fully non-linear time evolution in the bulk takes unstable states to stable ones.

The Critical Point Drying Method Applied to Scanning Electron Microscopy of L-929 Cells

1970 ◽  
Vol 28 ◽  
pp. 278-279
Author(s):  
Charles TurnbiLL ◽  
Delbert E. Philpott
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Surface Tension ◽  
Critical Point ◽  
Freeze Drying ◽  
Attractive Alternative ◽  
Crystal Formation ◽  
Critical Point Drying ◽  
Time Required ◽  
Scanning Electron

The advent of the scanning electron microscope (SCEM) has renewed interest in preparing specimens by avoiding the forces of surface tension. The present method of freeze drying by Boyde and Barger (1969) and Small and Marszalek (1969) does prevent surface tension but ice crystal formation and time required for pumping out the specimen to dryness has discouraged us. We believe an attractive alternative to freeze drying is the critical point method originated by Anderson (1951; for electron microscopy. He avoided surface tension effects during drying by first exchanging the specimen water with alcohol, amy L acetate and then with carbon dioxide. He then selected a specific temperature (36.5°C) and pressure (72 Atm.) at which carbon dioxide would pass from the liquid to the gaseous phase without the effect of surface tension This combination of temperature and, pressure is known as the "critical point" of the Liquid.

Morphological studies of linear (AB)n multiblock copolymers and their blends

1992 ◽  
Vol 50 (1) ◽  
pp. 384-385
Author(s):  
Richard J. Spontak ◽  
Steven D. Smith ◽  
Arman Ashraf
Keyword(s):  
Electron Microscopy ◽  
Microphase Separation ◽  
Multiblock Copolymers ◽  
First Order ◽  
Morphological Studies ◽  
Transmission Electron ◽  
First Order Phase Transition ◽  
Covalently Bonded ◽  
Total Molecular Weight ◽  
First Order Phase

Block copolymers are composed of sequences of dissimilar chemical moieties covalently bonded together. If the block lengths of each component are sufficiently long and the blocks are thermodynamically incompatible, these materials are capable of undergoing microphase separation, a weak first-order phase transition which results in the formation of an ordered microstructural network. Most efforts designed to elucidate the phase and configurational behavior in these copolymers have focused on the simple AB and ABA designs. Few studies have thus far targeted the perfectly-alternating multiblock (AB)n architecture. In this work, two series of neat (AB)n copolymers have been synthesized from styrene and isoprene monomers at a composition of 50 wt% polystyrene (PS). In Set I, the total molecular weight is held constant while the number of AB block pairs (n) is increased from one to four (which results in shorter blocks). Set II consists of materials in which the block lengths are held constant and n is varied again from one to four (which results in longer chains). Transmission electron microscopy (TEM) has been employed here to investigate the morphologies and phase behavior of these materials and their blends.

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