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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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Determining the position and spectral weight of Andreev states from a retarded Green Function

I'm trying to understand a result from the paper Josephson current through a correlated quantum level: Andreev states and $\pi$ junction behavior by Vecino, Martin-Rodero and Yetati (2003). ArXiv link ...
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Gauge fixing in Ginzburg-Landau simulation

I am developing a computer simulation of the Ginzburg-Landau model of superconductivity. In a few words, I have discretized the domain with finite differences and I am using Nonlinear Conjugate ...
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Does a superconductor conduct electricity at room temperature?

I know you need to cool a superconductor below a certain temperature for it to exhibit superconductivity, but do superconductors, specifically YBCO superconductors, conduct electricity normally at ...
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What are some examples of magnetocaloric materials?

I've recently become fascinated with a cryo cooling method known as "magnetic refrigeration". Here is the Wikipedia article. I was wondering if there is a list of magnetocaloric materials. ...
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Literature recommendations for superconductivity

What text books / review papers give an easy introduction to superconductivity? The literature should be suitable for Master students with some background knowledge in theoretical solid state physics ...
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Thermalizing bulk superconductors

I have been discussing with some friends whether or not (or how) bulk superconductors thermalize when placed in an environment far below their transition temperature. Suppose you have a cube of pure ...
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What is the atomic limit?

I am attempting to grasp topological superconductivity for an assignment and in trying to understand what makes a quantum system topological have came across the following paragraph; "In the case ...
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Spectral representation of a BCS gap function

I am playing with the spectral representation of a BCS gap function and I have trouble verifying causality properties. I find a divergence and I don't know what is the problem. Assume the gap ...
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spinless and time reversal symmetry breaking of p-wave pairing in topological superconductors

In the context of Majorana zero modes, I often hear that the p-wave pairing is effectively 'spinless' and time reversal symmetry broken. I understand that s-wave and p-wave refer to the spin portion ...
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How does Bohmian Mechanics explain superconductivity?

I'm looking for sources that discuss how Bohmian Mechanics explains superconductivity. Are there still Cooper pairs? Phonons? I saw one vague reference to vortices, but no details. This is my first ...
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What is the difference or connection between inverse proximity effect and triplet proximity effect in superconductors?

I know that inverse proximity effect affect the order parameter of the superconductor and that triplet proximity effect convert singlet Cooper pairs into triplets. But how is the two phenomena ...
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Is it possible to generate Ampere's force between the superconductor and the current-carrying wire?

In superconducting state, There is a current-carrying wire between the superconductor and the magnet,Is it possible to generate Ampere's force between the superconductor and the current-carrying wire?...
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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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Why in the BCS ground state the probability amplitudes are taken real?

In some references (see for example Ballentine ch. 18.5) the ground state of the BCS theory is assumed to be \begin{equation} |BCS\rangle = \prod_{\bf k} (u_{\bf k}+v_{\bf k}\hat{c}^{\dagger}_{\bf k,\...
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Reference request on Bogoliubov de Gennes (BdG) formalism

I have tried to gain an understanding about the BdG formalism by just following the calculations I found here and there of people bringing their superconducting Hamiltonians into matrix forms but I am ...
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On the magnetic field in the Meissner effect

As shown in the figure, in the Meisner effect, the magnetic field of the magnet bypasses the superconductor. My question is, does the magnetic B field belonging to the magnet increase at the arrow ...
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Energy gap in superconductors and the jump in specific heat

How the energy gap in superconductor arises, and how it is different from the semiconductor band gap? Is it true that jump in specific heat data, assures the energy gap. How to understand it ...
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What is BCS weak coupling Pauli limit?

What is BCS weak coupling Pauli limit Hp? How Hp=1.84Tc relation is derived? Please suggest suitable reference regarding that.
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What is clean limit and dirty limit?

In superconductor there has two limits, one called as clean and other one called dirty limit. But what are that meaning? What means clean and dirty? How the coherence length depends on the electron ...
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Aluminum critical current vs temperature fit

I have some data at different temperatures of Al's critical current (from 600 mK to 1.5K). Tc of Al is ~ 1.3. I am now trying to fit this data to a model to extract the theoretical critical current ...
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Does superconducting magnet prevents energy loss when hadron is being accelerated?

I read up on how synchrotron works and electron will heats up by emitting photon when it is steering(accelerating) around a bend, so more bends more heat loss. By heat I mean energy not necessarily ...
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About Supercurrent Direction in London Theory of Supercondutivity

I'm studying superconductivity starting from London's approach. After you obtain the two London's eqs you get for the static case: $\quad \nabla^2 \textbf{B}=\frac{1}{\lambda_L^2}\textbf{B}$ If ...
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How does a super current affect ductility, maleability and the mechanical properties of a superconductor?

In metals, the ductility, malleability, tensile strength and strain are all determined in part by their free electrons. I am wondering what would happen to all of these properties of a superconductor ...
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Hall effect in superconductors

In many papers on Hall effect in superconductors (in the mixed state), experimental results are plotted as magnetic field vs Hall angle. Why we need to consider the Hall angle in these cases? Can't we ...
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Why can't we have superconductors?

My book says, "Short circuiting occurs when the live wire comes in direct contact with the neutral wire, so a zero resistance path is provided to the current. A heavy current then passes through the ...
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Meissner effect

Meissner effect Why do field lines again get back to straight line after getting deflecting during superconducting state?
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BCS theory for neutral fermions

As I understand it, Cooper pairs form between two fermions and are the cause of superconductivity. I was told by a teacher that the formation of Cooper pairs and BCS theory requires both fermions to ...
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Superconductive magnet as a source of energy?

Could we charge a superconductive magnet and use it as a source of energy?
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Is there an magnetic field around ideal conductor?

Im gonna dive straight to the point: If you run some current through, say, copper wire you will get a magnetic field around it; that is how the gauss guns work. My questions are: 1) Is it possible ...
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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 would happen if a Type 1 superconducting sphere was placed over the north pole of a magnet?

This is a bit of a thought experiment but I thought it was rather interesting. I was doing research on superconductivity of Type 1 materials and how they repel magnetic flux due to the Meissner effect....
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Importance of Relative Grain Alignment in High Temperature Superconductors for High Current Applications

I'm currently studying superconductivity, and am attempting to work through a sample paper as exam preparation. Unfortunately, the lecture notes provided aren't of the highest standard and in certain ...
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Treating $-E_J \vert{\cos{(\hat{\theta}/2)}}\vert$ in the charge basis

I'm trying to write down the Hamiltonian for a Cooper pair box in the charge basis in the scenario where the Josephson potential term is not $-E_J \cos{\hat{\theta}}$, but $-E_J \vert{\cos{(\hat{\...
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Hydrogen Sulfide New Superconductor? Is It Possible For Hydrogen Sulfide?

According to a very trusted science source : https://www.zmescience.com/science/news-science/superconductivity-artic-temperatures-05342/ There is now such thing as a Hydrogen Sulfide Superconductor ...
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Temperature-pressure plot for superconducting records?

Eremets et al. (arXiv:1812.01561) and Hemley et al. (arXiv1808.07695) have reported new high-temperature record for superconductivity, as covered by MIT Tech Review and Physics Today. Not ...
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Would there be any current if an electric circuit is cooled to absolute zero?

My question is if I got a superconductor and cool it to absolute zero at least measurable by today's tool, it should have no electrical resistance but then would there be any current when there is a ...
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Tight-binding extended attractive Hubbard model for unconventional superconductivity

BCS theory suggest that the effective attraction between two electrons, due to electron-phonon coupling, is in momentum ($k-$)space. However, in literature, (real space) tight-binding Hubbard model ...
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What is 'Peak effect' in superconductivity?

I came across a phenomenon in type II superconductors called the "peak effect." To be a little more specific, it has something to do with delocalised vortices. I don't really know what is it all about....
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How is current in superconductors increased microscopically?

Imagine a superconductive ring with its current being increased by EM induction. How is current increased microscopically? I see only two possibilities: ...
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In superconductivity, does the diameter of the cable affect the current?

In the water tank analogy below, the smaller diameter pipe (B2) will drain tank A slower than the larger diameter pipe (B1) We are told that resistance has this same effect on current the bigger the ...
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Inductance in Superconductors

This is a picture I got from a question in this website, it seems totally fine, but if you try looking it gain, is the heater placed in the wrong position? Because as I know current takes the path of ...
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Does a battery 'excites' current to flow in a superconductor? [duplicate]

If yes, how is it possible since a closed circuit with no resistance means 0 voltage, how does the electrons flow initially if there's no potential difference? Any simple explanation or analogy would ...
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About the symmetry of interaction matrix element in superconductivity

In Sigrist, M. & Ueda, K. Phenomenological theory of unconventional superconductivity. Rev. Mod. Phys. 63, 239–311 (1991). There is equation 2.1 write as below $$H = \sum\limits_{{\bf{k}},{\bf{s}}...
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What are Cooper pairs in superconductivity? [duplicate]

At low temperature how does electron become Cooper pair and why can they pass through a superconductor without resistance? Please give quantum mechanical explaination.
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Why don't we have a “Cooper pair” of two holes in a superconductor?

The condensate of Cooper pairs is described by a complex scalar field (or the order parameter) which, when quantized can give rise (or is capable of creating) two types of quanta with charges opposite ...
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Is the hierarchy of Andreev bound state transmission probabilities fixed?

My question is regarding Andreev bound states and their transmission probabilities. But to make this self-contained, lets quickly recap, for which I will draw from Tosi, L., Metzger, C., Goffman, M. F....
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Do superconducter wires still have low resistance above their transition temperature?

Superconducting wires have almost zero resistance below their transistion temperature. But do they still have resistance better than other wires above that temperature?
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Derivation of BCS condensation energy

Many textbook derive BCS condensation energy as $$\begin{array}{l} {\left\langle E \right\rangle _s} - {\left\langle E \right\rangle _n}\\ = \sum\limits_{\left| {\bf{k}} \right| > {k_F}} {\left( {...
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Why is it that all metals do not become superconductor by lowering the ambient temperature?

Aluminium becomes a superconductor at a temperature below $1.91$K. But I am quite certain that all metals do not exhibit superconductivity even when the temperature is lowered to nanokelvin or below. ...
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Why does type-I superconductor behave differently than type-II as $H$ is increased?

As one increases the external magnetic field $H$ above a critical value $H_c$, a type-I superconductor abruptly changes to a normal conductor. But for type-II, the transition is not sharp but gradual ...