Questions tagged [phase-transition]

A phase transition is a change in the nature of a phase or in the number of phases of a system as a result of a change in the external conditions. Examples: melting/freezing, vaporization/condensation, ferromagnetic transition, superconducting transition.

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Can Lee-Yang zeros theorem account for triple point phase transition?

Now the prominent Lee-Yang theorem (or Physical Review 87, 410, 1952) has almost become a standard ingredient of any comprehensive statistical mechanics textbook. If the volume tends to infinity, ...
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577 views

Are there classical infinite order / continuous non-symmetry breaking phase transititions besides BKT?

At the Berezinskii-Kosterlitz-Thouless (BKT) phase transition, the singular part of the free energy behaves as $\xi^{-2}$, where $\xi \propto e^{c/\sqrt{T-T_c}}$ (with $c>0$) is the correlation ...
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273 views

Demystifying jamming in many-body systems

From a theoretical point of view, what has been the most successful approach to understanding jamming phenomena? I understand there's still a lot of debate around this subject, namely whether a ...
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287 views

Research: Mott insulator and topological order

I'm an experimentalist who is mainly focusing on strongly correlated electron systems (SCES), in particular Metal-insulator (Mott) transitions in the classical example $V_2 O_3$. Recently I decided to ...
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1answer
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Melting ice: reversible or irreversible?

I am looking into whether the melting of ice (or any substance for that matter) at constant pressure and temperature is reversible or irreversible. Different sources say different things, and it may ...
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231 views

Is there a way to obtain an RG flow equation for Quantum spin systems using MERA

We restrict ourselves to ground states of translationally invariant 1d quantum systems. I understand that there is the scale invariant MERA(multiscale entanglement renormalization ansatz) which ...
7
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555 views

Could sphaleron-induced proton decay also cause vacuum decay?

I will say right away that I don't mean standard-model sphalerons, I mean the sphalerons of some extension of the standard model. The reason to even think about this is last year's paper by Frampton ...
6
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48 views

Deducing the central charge of the Ising model from the free energy

My question is inspired by Di Francesco, Mathieu, and Senechal's Conformal Field Theory problem 3.5. Namely, the problem gives the fact that the free energy per particle of the 2D classical Ising ...
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51 views

In general, do critical points of continuous phase transitions have $\beta =0$?

Consider a phenomenological modelling of a continuous phase transition, where the Lagrangian of the system is given by $$L=\frac{a}{2}\phi^2+\frac{\lambda}{4}\phi^4-h\phi.$$ Here $\phi$ is the order ...
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146 views

Quantum phase transitions in a finite lattice

Sachdev begins his book on Quantum Phase Transitions by asserting that, for a system on a finite lattice, the ground state energy of a Hamiltonian H(g) (where g is some coupling) is a smooth, analytic ...
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237 views

Kosterlitz-Thouless in the XXZ chain: instanton condensation?

The anisotropic spin-$\frac{1}{2}$ Heisenberg chain $$H = \sum_n S^x_n S^x_{n+1} + S^y_n S^y_{n+1} + \Delta S^z_n S^z_{n+1}$$ is known to have the same physics as the two-dimensional classical XY ...
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303 views

What is the different between topological order and Landau's order in a system

I have thought about topological order for a long time, but I am still confused it. Roughly speaking in my understanding, the topological state is the eigen-state of some special symmetry such time ...
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284 views

Third-order topological quantum phase transition in p+ip superfluid

A two-dimensional spinless non-relativistic p+ip superfluid undergoes a quantum phase transition between the BCS (weakly-coupled) and BEC (strongly-coupled) regimes. This transition is driven by ...
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261 views

Lattice model completely constrained by boundary data

I am dealing with a lattice model that has the peculiar property that if I specify all the spins on the boundary, by local conservation laws, the whole lattice configuration (throughout the whole ...
6
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1answer
1k views

Upper critical dimension in field theory

Is there field theory which describe a second-order phase transition without upper critical dimension? Mermin-Wagner says something about lower critical dimension but nothing about upper dimension.
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2answers
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Bose-Einstein condensation and phase transition

I would like to ask the following question for which I cannot find a definite answer in the literature. Of what ORDER is the phase transition leading to Bose-Einstein condensation for a ideal and ...
5
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1answer
63 views

What happens when ice and water are placed together at the same temperature in an isolated system?

Suppose ice and water (not necessarily of the same mass) are both at $0^{\circ}$C and placed into a perfectly insulated, sealed container so that it is filled completely. If we leave this system alone ...
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299 views

Are order parameters ultimately subjective?

I keep bumping into order parameters in scientific papers, reviews, articles, etc, but I can never get a firm grip on them. Order parameters seem terribly subjective to me. Basically the way I ...
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307 views

Renormalization, Phase transitions and order parameters

Renormalization is the phenomenon for which, once a finite number of parameters, which are the couplings with positive-mass dimension, are fixed, then it is possible to express any $n$-point ...
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131 views

How the understand the idea of spatial dependent Fermi wave vector?

Recently, I have been reading the book by Naoto Nagaosa on Quantum field theory in Strongly Correlated Electronic Systems, but I got a problem in Chapter 3.2. When he discuss the idea of Bosonization ...
5
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1answer
290 views

How to classifies the distinct "plasma" phases of matter?

How to classifies the distinct "plasma" phases of matter? and What theory classifies the distinct "plasma" phases of matter? According to Wikipedia: Plasma (from Greek πλάσμα, "anything ...
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225 views

Nature of phase transitions in Kitaev honeycomb model

Short version of my question is this : what is the nature of the phase transition in the Kitaev honeycomb model ? Longer version: Kitaev honeycomb model undergoes a phase transition from a gapped to ...
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164 views

What is the relation between pseudogap and time reversal symmetry breaking?

Some papers concerning high-$T_c$ superconductor discuss the pseudogap and time reversal symmetry breaking. My questions are: What is the characteristic of order-parameter in pseudogap? How to ...
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199 views

Topolgical insulators order parameter

For topological insulators Is there any way to define order parameter for topological phase transitions?
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936 views

Goldstone modes and Heisenberg model

The ideia is to show that, because of Goldstone modes, 2d systems are quite different from 3d ones. So, considering the Heisenberg model, I'll post here what I'm asked to and my current thoughts on ...
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315 views

From vertex function to anomalous dimension

In a $d$ dimensional space-time, how does one argue that the mass dimension of the $n-$point vertex function is $D = d + n(1-\frac{d}{2})$? Why is the following equality assumed or does one prove ...
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51 views

Minor details of Mermin-Wagner

In the proof of Mermin-Wagner (e.g., scholarpedia), there is a minor assumption that the average magnetization $m_\Lambda (h)$ converges in the thermodynamic limit $\Lambda \to \mathbb{Z}^d$ to some $...
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How did I superheat my pasta water?

Last week I had an incident in the kitchen where I almost scolded my face with hot water. What happened: I was boiling some water in one pan and a sauce with veggies and meats in another next to it. ...
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60 views

How to calculate the emergent symmetry group in deconfined quantum critical point problem like $SO(3) \times Z_4 \to SO(5)$?

In the deconfined quantum criticality literatures like https://doi.org/10.1103/PhysRevX.9.041037, some equations are usually given: $$SO(3)\times Z_{4}\to SO(5),\\U(1)\times Z_{4}\to O(4),\\SO(3)\...
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What is the difference between order and correlation?

The concepts of correlation and order are ubiquitous in statistical physics and condensed matter but I have yet to find a reference that makes an order in the confusing terminology. As far as I ...
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72 views

Quantization during phase transition

Consider a scalar field $\phi(t,\vec{x})$ in $\mathbb{R}^{1,3}$ with the following lagrangian $$ \mathcal{L} = \frac{1}{2}\partial_\mu\phi\partial^\mu\phi - V(\phi) $$ where $V(\phi)$ is such that ...
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1answer
410 views

What is the order parameter of 2D generalized $XY$ model?

I'm now studying the phase transition of 2D generalized XY model. This model considered here has a mixture with ferromagnetic and nematic-like interactions, $$\mathcal{H}=-\sum_{\langle i j\rangle}\...
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123 views

Gapless modes at the boundary between topological insulator and normal insulator

I am currently learning about topology in condensed matter physics. I think I understand most of how topological indeces come about and differences between Z and Z2 indeces and the symmetries that ...
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61 views

Why does $[H,N]=0$ violate with superfluid phase judgement $\left<b\right>=0?$

I'm working with the standard Boson Hubbard model. It's Hamiltonian is defined in Fock space and commutes with total particle number N. $$[{{\hat H}_{BH}},\hat N] = 0$$ So I can simultaneously ...
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40 views

Energy conservation in cosmological phase transitions

Let us consider a cosmic phase transition, in which fermions $\psi_f$ condense and the vacuum expectation value $|\langle \bar{\psi}_f \psi_f\rangle |$ of the resulting fermion-bilinear field gives ...
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225 views

What is the Gaussian universality class of phase transitions?

In arXiv:1705.09309 it is said that Bose-Einstein condensation in ideal gas belongs to the Gaussian universality class. What is the Gaussian universality class of phase transitions? I know that a ...
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165 views

Percolation in Ultimate Frisbee (and Rugby, American Football, Basketball etc)

Question Has anyone ever investigated weather game dynamics in certain sports ever experiences a percolation-type transition with catching probability as the driver? Details I recently started ...
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637 views

A question in Quantum Phase Transition of Transverse Ising Model

In section 1.4 quantum Ising model of Subir Sachdev's book Quantum Phase Transitions, he discusses the quantum phase transition of transverse quantum Ising Model at zero temperature (so we just focus ...
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642 views

What's the most stable crystal lattice for a collection of spherical toy magnets?

I recently found a bunch of tiny spherical toy magnets, and I've been having fun sticking them into various shapes. In two dimensions, there are only two possible packings of the magnets: a square ...
4
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302 views

Phase transitions, Landau Ginzburg theory and Symmetry reduction

On one side of critical temperature (usually for $T<T_{c}$), symmetry is reduced w.r.t the symmetry on the other (usually $T>T_{c}$) regime. I heard on the road (near a theoretical physics ...
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836 views

Does the Mermin-Wagner theorem forbid superconductivity in the 2D Hubbard-Model?

"In the 2D Hubbard model (two spatial dimensions) the Mermin-Wagner theorem does not allow a phase transition." I am quite illiterate concerning this theorem and hearsay. Does the theorem ...
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95 views

Example of critical (non-relativistic) quantum field theory in 1D?

Is there an example of a critical non-relativistic bosonic quantum field theory in 1D (no time)? So, the field theory can be describe by annihilation, $\psi(x)$, and creation operators, $\psi^\dagger(...
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Do finite sized 1D Hamiltonians have free energies which are analytic everywhere in the complex plane?

It's well known that 1D classical and quantum short-ranged Hamiltonians have free energies which are analytic/holomorphic everywhere as a function of inverse temperature $\beta=1/k_BT$ (see Araki, &...
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101 views

Hertz-Millis theory and quantum criticality

Hartz-Millis(HM) theory is a model which exhibits quantum phase transition. The HM action following Altland & Simons is given by $$ S = \frac{1}{\beta}\sum_{\omega_{n}}\int \frac{d^d q}{(2\pi)^d}\...
3
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1answer
81 views

Why does wind blowing across a bird bath cause the water to freeze even though the ambient air temp is 39 - 40 degrees F?

Frequently, after cold frontal passage, a strong NW wind blows across the open marsh and through our back yard. With ambient temps still well above freezing, the surface of the water in our concrete ...
3
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1answer
56 views

Weak localization, strong localization, and localization without a metal-insulator transition

As I begin to read literature on Anderson localization by disorder, authors are distinguishing between cases that are unfamiliar to me, namely weak localization, strong localization, and localization ...
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45 views

Physical meaning of gapped path between Hamiltonians in the same phase

I'm reading this famous paper about the classification of quantum phases, and I'm wondering about the physical meaning of the definition of phases the authors use. They say that two Hamiltonians $H_0$ ...
3
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49 views

Can a finite simple symmetry group be spontaneously broken in stages, with multiple phase transitions?

Can a finite simple symmetry group $G$ be spontaneously broken in stages, with two or more phase transitions, each one leaving a successively smaller unbroken subgroup? By simple, I mean no normal ...
3
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575 views

What's the definition of Goldstone Mode?

My question is how to define a Goldstone Mode? Initially I thought that Goldstone Mode is a consequence of spontaneous symmetry breaking, but later I learned that in Kosterlitz–Thouless transition, ...
3
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1answer
107 views

Is Landau free energy really the free energy?

I recall reading in Negele&Orland's book that Landau free energy function is not really the free energy that one obtains from the partition function $$F = -\frac{1}{\beta}\log Z.$$ Indeed, the ...

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