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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How does phonon cause two electrons to attract each other?
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 traveling at some speed wont ...
3
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2answers
227 views
Why does a superconductor obey particle-hole symmetry?
We normally solve the Bogoliubov-de Gennes (BdG) equations in order to compute the energy spectrum of a superconductor. The Nambu spinor is a common object that is used in formulating these equations. ...
3
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2answers
164 views
Superconducting gap, temperature dependence: how to calculate this integral?
Tinkham (page 63) states that the temperature dependence of the gap energy of a superconductor $\Delta(T)$ can be calculated using the following integral:
How can this actually be carried out? I am ...
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3answers
197 views
Induction cooker + superconductive pot
What will happen if I put a super-conductive object on an induction cooker, and turn the cooker on?
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1answer
31 views
Superconducting magnet
This is a somewhat more detailed question related to this one. The problem I want to solve is problem 1 here. What I tried:
a) From $V=-L\frac{\mathrm{d} i}{\mathrm{d} t}$, we can integrate and ...
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0answers
23 views
Superconducting solenoid [closed]
I'm trying to solve the following exercise:
A superconducting solenoid made of Ta is cooled by liquid Helium. The solenoid is made of a thin wire (diameter 1mm). The diameter of the solenoid is 3 cm, ...
6
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1answer
223 views
Relativistic drift velocity of electrons in a superconductor?
Is there a formula for the effective speed of electron currents inside superconductors?
The formula for normal conductors is:
$$ V = \frac{I}{nAq}$$
I wonder if there are any changes to this ...
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1answer
45 views
Superconducting diamagnetic sphere in uniform magnetic field
What is the size of the magnetic dipole moment $\vec m$ of a superconducting diamagnetic sphere $radius=R$ in a uniform magnetic field $\vec B_0$? Since there is no free current, we can solve for ...
3
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1answer
98 views
Flow of supercurrent in a superconductor
I have two questions one practical and one theoretical. Even though I have a decent understanding of superconductivity both phenomenological as well as theoretical (i.e. BCS), some things just slipped ...
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1answer
212 views
What is the “BCS Cooper pair condensation” as a physical phenomenon in terms of experiments?
"Thought" experiments and "numerical" experiments are allowed.
This question is motivated by the question Has BCS Cooper pair condensate been observed in experiment? ,
and by our recent research on ...
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5answers
2k views
How can Ohm's law be correct if superconductors have 0 resistivity
Ohm's law states that the relationship between current ( I ) voltage ( V ) and resistance ( R ) is
$$I = \frac{V}{R}$$
However superconductors cause the resistance of a material to go to zero, and ...
1
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1answer
62 views
Interaction strength in BCS theory
I'm looking to plot the band gap $\Delta(T)$ as a function of temperature between $T = 0$ and $T = T_c$ by numerical evaluation of the band gap equation
$$\frac{1}{\mathcal{N}(0)V} = ...
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1answer
126 views
Superconductor: What form of paramters (like London penetration depth) to use?
I am dealing with thin film and LN2 temperature, and am trying to calculate values such as the Pearl Length, but am trying to find clarification as to which value of $\lambda_L$ to use in this case. ...
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0answers
46 views
Superconductivity [duplicate]
What is the correct explanation of why superconductivity occurs in metals when they are cooled to a temperature below $T_c$?
My textbook has the following explanation:
Superconductivity is the ...
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0answers
57 views
Some questions about the edge states for time-reversal invariant topological superconductors?
Stimulated by my some recent calculations on edge states(ES) for time-reversal invariant(TRI) topological superconductors(TS) as well as many questions concerning the "edge states" in Physics ...
2
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1answer
79 views
Ginzburg-Landau model for superconductivity
Could someone kindly elaborate more on the Simple Interpretation section from this Wikipedia Article? I refer to the part on the natures of $\alpha , \beta$. Why can one assume that ...
6
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3answers
561 views
Measuring the spin of a single electron
Is it possible to measure the spin of a single electron? What papers have been published on answering this question? Would the measurement require a super sensitive SQUID, Superconductive Quantum ...
1
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1answer
91 views
What is the importance of the Fermi energy $E_F$ or the chem. potential $\mu$ for topological superconductors
A lot of effort is put into shifting the Fermi energy of a topological insulator to exactly zero which then provides some advantages when this TI is coupled with a superconductor.
I don't understand ...
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0answers
40 views
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 ...
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3answers
573 views
Shine a light into a superconductor
A type-I superconductor can expel almost all magnetic flux (below some critical value $H_c$) from its interior when superconducting. Light as we know is an electromagnetic wave. So what would happen ...
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1answer
120 views
What is a $p_x + i p_y$ superconductor? Relation to topological superconductors
I often read about s-wave and p-wave superconductors. In particular a $p_x + i p_y$
superconductor - often mentioned in combination with topological superconductors.
I understand that the overall ...
1
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0answers
59 views
How is a Majorana fermion created when a s-wave superconductors is in proximity to a topological insulator (e.g. via an antidot)
Kane and Fu proposed a few geometries how to create Majorana zero modes using a s-wave superconductor in proximity to a 3D topological insulator (TI).
-> ...
3
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1answer
78 views
Electrical energy storage in superconductors
I am a first year A-level student and I am doing a project about the possibility of storing electrical energy in a superconductor. I have researched and I am aware of the critical current density and ...
1
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1answer
67 views
What is paramagnetic current-current correlation?
I know what paramagnetism is. But first I want to know about the paramagnetic current and then the above-mentioned correlation?
Actually, I am working on a paper on superconductivity where I have ...
5
votes
1answer
180 views
A question on the doped Kitaev-Heisenberg model?
Recently, some groups have studied the effects of doping the Kitaev model on honeycomb lattice(e.g.,http://arxiv.org/abs/1109.6681 and http://arxiv.org/abs/1109.4155) and their calculations show the ...
2
votes
2answers
174 views
Has BCS Cooper pair condensate been observed in experiment?
Feshbach resonance in s-wave scattering states a BCS Cooper pair condensation at B-field just above the resonance where the scattering length a <0. Just wondering if the condensation has been ...
3
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1answer
266 views
Effects of parallel superconducting plates
Assuming the existence of virtual particle field ( zero point energy field) Casimir force is produced by 2 parallel conducting plates excluding some of the frequencies between the plates, if these 2 ...
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0answers
88 views
Superconductors for sale? [closed]
Does anyone know where I can purchase superconductors for a school presentation? I don't need a whole kit, just the disk itself. Thanks.
3
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1answer
182 views
Zero Resistance in Quantum Hall Effect and Superconductivity
What is the difference between the zero resistance of $R_{xx}$ in integer quantum Hall effect and the zero resistance in superconductivity?
4
votes
2answers
214 views
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 ...
5
votes
1answer
245 views
What does “particle number conservation” mean in condensed matter physics?
What exactly does it imply about a condensed matter system to have particle number conserved or not conserved?
For example, why does the superconducting phase break particle number conservation while ...
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0answers
46 views
Effect of strength of magnetic field on the height of a levitating superconductor?
Quantum levitation, flux pinning -- basically, when a superconductor floats above a permanent magnet, is really fascinating. But does the strength of the magnetic field influence the superconductor's ...
1
vote
2answers
188 views
What exactly is superconductivity?
Does superconductivity mean that the coulomb force or some magnetic force has gone up? I guess that it applies only to wires which get less resistance due to cooling... Is this wrong?
Also, Are there ...
8
votes
3answers
1k views
Can superconducting magnets fly (or repel the earth's core)?
If a superconducting magnet and appropriate power supply had just enough $I\cdot s$ (current $\cdot$ length) so that when it was perpendicular to the earth's magnetic field, the force of the ...
2
votes
1answer
115 views
Crystal magnetic response only skin deep?
The Hamiltonian for a single electron in a magnetic field reads
$$H=\left(\frac{{\bf p}^{2}}{2m_{e}}+q_{e}\phi\right)+\mu_{B}\left({\bf \hat{L}}+g{\bf \hat{S}}\right)\cdot{\bf ...
4
votes
2answers
239 views
Layman explanation for superconductivity?
I'm interested in reading an explanation of superconductivity, but though I have an undergraduate degree in engineering, I'm not sure I'm up to reading a detailed mathematical treatment of the theory. ...
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2answers
244 views
Superconducting Wavefunction Phase (Feynman Lectures)
In Volume 3, Section 21-5 of the Feynman lectures (superconductivity), Feynman makes a step that I can't quite follow. To start, he writes the wavefunction of the ground state in the following form ...
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0answers
90 views
Superconductor general concept questions
I was thinking about building an electric motor using superconductors and I have some general concept questions in regards to how the behavior might be different from ordinary wires.
The Meissner ...
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1answer
181 views
Faraday's law and superconductivity
According to Faraday's law of induction, volts = -Number of coils in a solenoid * change in strength of magnet / change in time. This doesn't take into account distance or speed, only time. If amps = ...
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0answers
39 views
What is meant by the quantum integrity in a superconducting loop
I encountered this in the context of using squid microscopy to test for d-wave pairing in an iron arsenide superconductor where the goal of the experiment was to detect half integer flux quantum ...
2
votes
1answer
46 views
What are virtual excitations in the context of superconductors?
In a superconductor I have read that the energy gap can be defined as the energy difference between the ground state and the virtual excitations of the system. Is this the energy required to form a ...
5
votes
2answers
296 views
How do superconducting materials float in magnetic field?
The movie Avatar got me interested in the subject, but so far I only found sophisticated articles loaded with unfamiliar words. Is there a simple way to explain how magnetic field affects ...
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0answers
40 views
How fast is an anti-quench?
Is there any evidence it is slower than a quench?
The rapid, energy-rich return of a superconducting electromagnet to the normal state is called a quench, and occurs very rapidly, perhaps almost ...
3
votes
2answers
716 views
Quantum levitation (locking) 3mm thick disk could carry 1000kg small car claim
I watched this TED presentation: http://www.ted.com/talks/boaz_almog_levitates_a_superconductor.html
It is about superconductivity and quantum levitation. It tells that super-thin, three-inch disk ...
5
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3answers
292 views
Why can't a superconductor make a DC motor self sustaining?
Superconducting wire can host a low current magnetic field. I do not know if it supports a corresponding electrical field.
Can a superconducting wire that sustains a current accelerate a DC motor? ...
4
votes
1answer
173 views
Can i use coils with compressed air to make a superconductor?
What im saying is inside pipes i am going to use compressing so that that in the places with low pressure they cool the superconducotor. is this possible? Can i use this concept to make ...
10
votes
4answers
578 views
Usage of helium in MRIs
More and more articles pop up on the shortage of helium, and on the importance of it. Its usage in MRI's spring to mind for example. I looked it up and found out that helium is used for its 'low ...
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1answer
30 views
Superconducting nanowire in a parallel magnetic field
Consider a nanoscopic wire (with radius $R$) of superconducting material. The wire lies along the $z$-axis and a magnetic field $\mathbf{H}_a = H\mathbf{e}_z$ is applied. The magnetic field is too ...
5
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2answers
172 views
Meissner Effect for Type-II Superconductors
I was wondering whether the breakdown field strength for the Meissner effect may be attributed to the Zeeman effect? I can see the latter (along with the Stark effect) to be more analogous to electron ...
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4answers
146 views
The requirements for superconductivity
Which properties are sufficient evidence for a material to be not superconducting?
I am looking for a set of statements like
If the material is semiconducting, it is not superconducting
Edit:
I ...
