Questions tagged [superconductivity]
Superconductivity is the transmission of current with no resistive losses, and is one of the most active areas of condensed matter physics research.
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Relation between p+ip wave Superconductor and Moore-Read State
I am quite interested in the understanding of the relation between p_ip wave superconductor(SC) and the Moore-Read(MR) state.
They share many similar properties, for example, p+ip SC has majorana as ...
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Can superconductors undergo a BKT transition?
In the article by Kosterlitz and Thouless (1973) they write in the abstract: "This type of phase transition (BKT) cannot occur in a superconductor for reasons that are given". Later in the paper they ...
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What is Robert B. Laughlin saying about quantum field theory?
Robert B. Laughlin, A Different Universe states the following concerning the relationship between superconductivity and quantum field theory. I do not understand why he says "the microscopic ...
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Where does the phase difference come from in a Josephson Junction?
When you separate two superconductors by a thin insulating film, a current $I(t)=I_0 \sin{\theta(t)}$ flows between the superconductors, where $\theta$ is the phase difference between the ...
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How does a phonon cause two electrons to attract each other and form a cooper pair?
We know that like charges repel each other. But my professor claimed that two electrons can attract each other as well. What he said was that due to screening an electron travelling at some speed won'...
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Are photons inside the media massive? If yes, why there is no Meissner effect?
We all know in vacuum travels with speed $c$, hence its rest mass has to be 0. In the media the light speed $v<c$. Then the photon renormalized by the medium (call it "quasi-photon" if ...
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What do massive photons have to do with superconductivity?
I keep reading that the idea of massive photons leads to an explanation of the Meissner effect but I fail to see how photons are involved with the repulsion of fields inside a superconductor.
How ...
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Gapless superconductivity
I don't understand what is meant by "gapless superconductors". As far as I know, the superconducting gap is necessairy for both zero resistance and the Meissner effect, the two hallmarks of ...
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What is the Difference Between a Type-1 and a Type-2 Superconductor?
As the title says, I was wondering what the difference was between a Type-1 and a Type-2 Superconductor. Especially in terms of the Coherent Length and Penetration Depth of a Magnetic Field - and how ...
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Difference between Charge Density Wave (CDW) and Superconductivity?
I am struggling to see the difference between these two mechanisms.
If they are both electron-phonon mediated and both distort the lattice then why don't Cooper pairs form at the CDW transition ...
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Topology and Superconductor Symmetry Breaking
I read an article today on stack exchange titled "Superconductor Symmetry Breaking". The 2016 Nobel Prize was awarded for research on topological phase transitions in the study of superconductors and ...
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BCS theory: where did all the bosons go?
After perusing BCS theory, I am perplexed by a seeming inconsistency. On the one hand, at the motivational level, it introduces bound, hence bosonic, Cooper pairs, which justify condensation ...
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Electric charge conservation in a superconductor
In a superconductor, $U(1)$ gauge symmetry is spontaneously broken. But $U(1)$ gauge symmetry is responsible for conservation of electric charge. Then it appears to me that the electric charge ...
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Alternative to Cooper pairing in superconductivity
BCS theory, in which electrons form Cooper pairs, has been successful in explaining conventional superconductivity. Physicists have adopted similar pairing mechanism in an attempt to explain high-...
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How to understand the "condensation" of Cooper pair in BCS theory?
Condensation
First of all ,what I understand about "condensation" is that: there exists macroscopic occupation in one or more than one states, i.e. there exists a state $|i\rangle$ with ...
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BCS state with well-defined particle number - interpretation?
It's common knowledge (and has been discussed in other questions on this site) that the standard BCS ground state $ \left|\Psi_{BCS}\right\rangle = \prod_k \left( u_k + v_k c_{k\uparrow}^{\dagger} c_{-...
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Maximum electron-phonon coupling SC temperature
In many articles and web pages I found people claiming that the maximum critical temperature for superconductivity in the BCS framework is about 40K.
Sometime, more accurate writers report that the ...
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If increasing applying energy to an atom excites electrons, why does electrical conductivity decrease as temperature increases?
Applying energy to an atom makes the electrons jump up to higher energy levels. This is known as excitation. Electrons on higher energy levels are easier to remove from an atom than those on lower ...
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What symmetry class does 1D spinless $p$-wave superconductor belongs to?
$Z_{2}$ topological invariant exist for Kitaev model.
What symmetries does it conserve? And to what symmetry class it belongs to?
The hamiltonian for kitaev model can be written as
$$
H=\sum_k \...
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Superconducting wire with temperature gradient
If you have a piece of wire that is a superconductor (say Niobium), and you hold the temperature at one end above $T_c$, and the other end below $T_c$ -- would you have a state of both superconducting ...
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When was the first time that superconducting quasiparticles were called Majorana fermions?
Since a number of years, the field of superconductivity has a growing obsession with Majorana fermions. I wonder how far back we can go: When was the first time that superconducting quasiparticles ...
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Superconductivity in graphene with spin orbital coupling, is it proper to let the order parameter on two sub-lattice equal?
I am reading this article: Edge superconducting correlation in the attractive-U Kane-Mele-Hubbard model.
Considering just the first part of the article, where a negative-U Hubbard model with the ...
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Why is the AdS/CFT approach to superconductors rarely cited in condensed matter publications? [closed]
Let me put things into perspective by comparing with other applications of string theory. Nowadays review papers written by cosmologists about inflation models often discuss string theory scenarios ...
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London theory, an electromagnetic description?
Currently I'm reading "Introducton to Solid-State Physics" by Charles Kittel, 8th edition and about superconductivity. I'm having a bit of trouble getting the whole plot, because as far as I'm ...
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How can Cooper pairs form in zero temperature, if there are no phonons?
Phonons behave like Bosons, so they have a Bose Einstein distribution. If you take the zero temperature limit, the distribution vanishes. So at zero temperature there are basically no phonons (up to ...
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First-principles calculation of the critical temperature of a superconductor
Special materials become (conventional) superconductors at a specific temperature, referred to as the critical temperature.
Are there any techniques for calculating from first principles whether a ...
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Seiberg-Witten theory and Superconductivity
There seems to have some (deep) relation between Seiberg-Witten theory and superconductivity. e.g. this Witten paper.
Q: Could someone introduce the relations between the twos both physically in ...
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Why are Topological Superconductors hard to make?
Topological insulators (TI) have already been made in lab. Topological superconductors (TSC), being close cousins of TI, seem harder to make.
Why is that?
It seems that materials in connection with ...
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Can superconductivity be understood to be a result of quantum entanglement?
I've been trying to find out what causes superconductivity. I have seen a lot about what characterizes it (e.g the Meissner effect). But I haven't found much on the root cause.
The closest I have ...
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What do we know about the strength of the electron-phonon coupling in high-temperature superconductors?
I would like to clarify the situation of the electron-phonon coupling in high-temperature superconductors (or considering only the cuprates). The main question is what do we know about the strength of ...
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