The study of physical properties condensed phases of matter, including solids and liquids.

learn more… | top users | synonyms

2
votes
1answer
41 views

Green Kubo formalism valid for inhomogeneous systems?

I'm interested in nano-composites and their effective properties and I use classical Molecular Dynamics as computation method. My question is: "Can I still use the Green Kubo formula to calculate ...
3
votes
0answers
29 views

Can different Floquet replicas be distinguished (within Floquet's theorem)?

According to Floquet's theorem, two quasi-energies separated by $n\hbar \omega$ represent the same state. According to this, I would think different replicas are indistinguishable experimentally. ...
0
votes
0answers
27 views

References on Josephson ring modulators

I would like some good references on Josephson junctions and, in particular, Josephson ring modulators. I know that Devoret has written a handful of papers and notes on JJs, but I am hoping to find ...
1
vote
0answers
18 views

Diamagnetic materials are very rare, compared to paramagnetic and ferromagnetic materials, right? [closed]

For a material to be diamagnetic, it should have zero intrinsic magnetic dipole. Therefore, most materials are not diamagnetic, right?
0
votes
0answers
59 views

What will a glass look like in 500 years?

The glass is in a metastable state. It is changing constantly. So what will a piece of glass look like in 500 years in room temperature?
3
votes
3answers
65 views

Relation between boiling, vapour pressure and atmospheric pressure

The boiling point of water is always defined as the temperature at which the vapour pressure of water is equal to the atmospheric pressure. How does the definition relate to why there is intense ...
1
vote
0answers
55 views

Reverse-engineering an equation of state

Suppose we have a fluid of some kind with a (let's keep it simple) barotropic equation of state: $p = p(\rho)$. Typically, I see that one starts with a function $p$ and $\textit{then}$ solves the ...
3
votes
1answer
74 views

“distinguishability” of 1D identical particles

Recently when I deal with 1D electron system, it occurred to my mind that since these electrons are not able to bypass each other during the scattering processes, we can actually label them as the ...
2
votes
0answers
39 views

2-loop $\phi^4$ at finite temperature [closed]

When evaluating diagrams that contribute to the 2-loop effective potential $V_{eff}$ in $\lambda \phi^4 $ theory at finite temperature one has to calculate diagrams of such type which equals to ...
0
votes
2answers
41 views

Translating Electronic Bands back to first Brilluoin Zone

For phonons, I understand why we can translate everything back into the first Brillouin Zone: there is a minimum wavelength defined by two lattice sites. For electrons, which are delocalized, I see ...
0
votes
0answers
11 views

Diffusive or balistic? Spread of the wave packet when localized and extended states coexist

If the lattice is perfectly periodic, then the wave packet of a particle initially located on a site spreads balistically. Namely, its size increases linearly in time. Now, introduce disorder into ...
1
vote
0answers
33 views

Reference for open XX spin chain with external magnetic field

I would like a reference on the diagonalization of an open XX spin 1/2 chain with homogenous external magnetic field. I am new to the subject and I haven't been able to find a reference for it. Edit: ...
2
votes
1answer
52 views

Soft Condensed Matter book for self study

I'm a junior undergraduate in physics & materials science. I've had half of a course in quantum mechanics taught out of Townsend's book (We've gone from beginnings of matrix mechanics to the ...
2
votes
0answers
45 views

Numerical problem with Hartree-Fock equations for dilute Bose gas

I have to solve the following set of equations self-consistently: $$\begin{align} n_c(\mathbf{r}) & = \frac{1}{g}\left[\mu - V_{\rm ext}(\mathbf{r}) - 2 g n_{T}(\mathbf{r}) \right] \\[3mm] ...
7
votes
0answers
100 views

Is there a database or a classification of High-temperature superconductors?

I was wondering if there exists a list with all (or most of) the High-$T_c$ superconductor materials. In particular I'd like to know if there are databases or review that classifies them by their ...
3
votes
1answer
60 views

Temperature dependence of magnetic domains

Does the size of magnetic domains depend on temperature ? Not able to find any papers on this subject, maybe because there is no such dependence...
0
votes
2answers
79 views

1D superconductivity does not exist even at zero temperature?

In class Professor claimed that 1D superconductivity does not exist even at zero temperature. I did a preliminary search and found papers on 1D superconductors. Did I or the Prof make a mistake or ...
-1
votes
1answer
22 views

cicumfernatial vector

Once a sheet of graphite is rolled up into a nanotube, the allowed values of k are constrained by the imposition of periodic boundary conditions along the circumferential direction. this periodic ...
1
vote
0answers
44 views

Why use coherent state path integral? What is its motivation or goal?

In almost all textbooks of quantum field theory for high energy, they insert the position and momentum eigenstate to formulate the path integral. While in condensed matter field theory, they insert ...
0
votes
0answers
34 views

Difference between three mutually complementary methods: Raman, Infra-red spectroscopy and inelastic incoherent neutron spectroscopy?

When I read the wiki on Raman spectroscopy, I found a paragraph explaining what system is suitable for using Raman and what others do not. It provide two other method as shown in title: infrared ...
0
votes
1answer
53 views

Derivation of Hartree-Fock equations using 2nd quantization [closed]

I derived the following effective Hamiltonian: $$ H_{eff} = \sum_k{ \left( \, \epsilon_k + \sum_{k_2}{\left(<k \, |<k_2 \, |\,u\,| \, k_2>|\, k> - ...
-1
votes
1answer
38 views

The Definition of Hall effect [closed]

I'm studying in Electricity course in my collage the Hall effect. What is the Hall effect in simple way please?
0
votes
1answer
39 views

Angular momentum partial components of a $k$-dependent pairing potential

I am going over this review on pairing in unconventional superconductors :http://arxiv.org/abs/1305.4609v3 which on page 21 states that for a "regular" function $U(\theta)$, partial components $U_l$ ...
0
votes
1answer
119 views

can a gapless system be a topological state?

For a gapless system without boundary (i.e. in the bulk there is gapless excitation while no clear meaning of boundary excitations like QFT), can it be a topological state? What is the property of EE ...
1
vote
1answer
40 views

What is the underlying transport mechanism of electron drift in metals?

The equations involving drift speed, mobility and conductivity, $v_d=\mu E$ and $\sigma=\mu e n$, treat electrons in a Newtonian way. This model works well in practice (at least in macro scale), but I ...
1
vote
1answer
38 views

What's the difference between charge density wave and charge ordering for superconductors

So far, my understanding is that they are the same. Charge ordering is a phase transition and the material will have charge density waves once it's in a charge ordered state...? This sounds too simple ...
0
votes
1answer
23 views

Why higher FAT level implies more signal in XPS analysis?

In XPS analysis, the FAT (Fixed Analyzer Transmission) parameter controls the electrostatic field of an emispheric analyzer, called Pass Energy $E_P$. The FWHM of a peak of signal is given by ...
1
vote
1answer
69 views

How does Galitskii's integral converge?

In V M Galitskii's 1958 paper "$\textit{Energy spectrum of a non-ideal Fermi Gas}$," he builds the following integral as part of a longer expression for the real part of the self-energy (eqn 26'). It ...
1
vote
1answer
78 views

Berry phase in the toric code model and 2D chiral $p$-wave superconductors

When we derive the exchange statistics by moving quasiparticles around a circle in the toric code model we do not mention any Berry phase contribution. Is the Berry phase contribution trivial or it ...
2
votes
0answers
40 views

Proof that magnetic Bloch waves are almost periodic in the reciprocal index

I would like to prove that the magnetic Bloch waves change by a phase factor if you shift their crystal momentum by a reciprocal lattice vector. That is, if $u_{n,\mathbf{k}}(\mathbf{r})$ is a Bloch ...
0
votes
0answers
18 views

Quasi-electron lifetime at Dirac (Weyl) point

I would like to know how one should calculate the electron lifetime with chemical potential at the Dirac point from Fermi Golden Rule: \begin{equation} ...
2
votes
2answers
49 views

Are there materials that strongly (macroscopically) vibrate under light of certain frequencies? If so why?

Picture an imperfect plane of loose particulate matter like sand or silt. Are there materials where if I shine light (not isotropically) on the plane I could get the particles to vibrate with large ...
1
vote
1answer
52 views

What is the difference between Fermi level and Fermi edge?

Just as in title: What is the difference between Fermi level and Fermi edge? My friend makes some research about XPS and he encountered this term. He knows what is Fermi level, but never heard about ...
0
votes
1answer
44 views

Is there any one lattice tight banding model (2D) hosts Dirac points as graphene does?

graphene has a two sublattice structure and it hosts two Dirac points. I wonder if there is some two dimensional lattice geometry which is simpler than honeycomb lattice, but also host Dirac points.
2
votes
0answers
38 views

Difference between a Hamiltonian and its mean-field form?

In most solid state physics text books, BCS theory is introduced in the following way: The authors introduce a mean-field parameter (based on the superconduncting pair) and upon that, they reduce the ...
1
vote
2answers
74 views

Dirac monopole of Berry curvature?

We know that there is an effective "magnetic field" in terms of Berry curvature, which leads to Luttinger's anomalous velocity, etc; and similarly there is also a "magnetic flux", which appears in ...
0
votes
0answers
43 views

Three-dimensional flat bands and how to create them?

Consider a three-dimensional non-interacting system with translational invariance. It is easy to create a two-dimensional flat band by putting this system into a uniform magnetic field. The energy ...
1
vote
0answers
43 views

Photon absorption and emission in 2nd quantization

I am looking for models which describe the interaction of matter (lets take a 1D chain of atoms) with photons, especially the emission and absorption. I would love to see the derivation of models in ...
0
votes
2answers
83 views

Why do Weyl points come in pairs in solid state system?

Quoted from "Beyond Band Insulators: Topology of Semi-metals and Interacting Phases" by Turner and Vishwanath: In 3D lattice models, Weyl points always come in pairs of opposite helicity; this ...
0
votes
0answers
27 views

Numerically evaluating momentum sums

For many-body systems, calculations often involve momentum sums, which are ultimately evaluated numerically for a finite system size $N$. The larger $N$ is, the more accurate the results. Is there ...
0
votes
0answers
30 views

Cooper Pair Breaking and Quasiparticle Excitations

My question concerns the breaking of Cooper pairs and the excitation of quasiparticles. At T = 0 all electrons are condensed in the ground state as cooper pairs. If one increases the temperature one ...
1
vote
0answers
67 views

Derivation of open boundary conditions for Non-Equilibrium Green's Function (NEGF)

It is widely claimed that the Non-Equilibrium Green's Function (NEGF) equations for the study of quantum transport have been derived from the many-body perturbation theory (MBPT). Yet the bridge ...
1
vote
0answers
42 views

Effect of doping in Superconductor

Doping an element (for example element substitution) could be lower down the critical temperature of superconductor, but i don't know the mechanism behind this, is it because more bosons need to ...
1
vote
0answers
35 views

Helium 3 atoms as fermions?

Helium atoms are composite particles so a priori their "single-particle" (in this case single atom) state is very complicated. They are nevertheless well-modeled by elementary fermions models like ...
1
vote
0answers
28 views

Twin and Detwin Crystals [closed]

Hello i would like to ask , what are twin and detwin monocrystals? what has to do with their crystalographic symmetry? any consequences ? any image also would be really helpfull! Thank you
0
votes
0answers
25 views

Rotational invariance of on-site repulsion term in Hubbard model

I'm trying to prove to myself something I assumed that was obvious: that the term $n_{\uparrow} n_{\downarrow} = \widetilde{n}_{\uparrow} \widetilde{n}_{\downarrow}$ where, $n_{\sigma} = ...
1
vote
1answer
61 views

Looking for a specific theory concerning Dark Matter [closed]

I am looking for the name of a theory positing that "empty" space itself is not empty, but has substance, and that "fabric" or "substance" is actually what we call Dark Matter. In theory, dark matter ...
3
votes
2answers
102 views

Difference between DMRG (density matrix renomalization group) and MPS (matrix product states)?

I am learning DMRG recently. I noticed there are many papers both in the DMRG approach and MPS (such as variational matrix product state (VMPS) by F.Verstraete and J.I.Cirac) approach. In my eyes, ...
2
votes
1answer
59 views

Particles, quasiparticles, and “stability”?

So I'm studying Fermi Liquid Theory, which concerns itself with quasiparticle excitations made by superpositions of single-electron wavefunctions. We create particle-like wavepackets which exist for ...
3
votes
1answer
108 views

Particle-Hole transformation in Superconductor

The Bogoliubov - de Gennes equation has a emergent particle-hole symmetry: $$ \mathcal{P}H\mathcal{P}^{\dagger} = -H\text{.} $$ My question is now what happen to the Nambu spinor: $$ ...