# Tag Info

## New answers tagged superconductivity

3

What are phonons? Phonons aren't particles like electrons or protons are, phonons are quasi particles, these type of particles are just used to describe excitations of a field: in phonons case, phonons are used to describe elementary lattice vibrations which have certain frequency. Electron-Phonon Interaction: Basically Cooper pairs are just pairs of ...

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Introduction: Superconductivity is phenomenon when certain materials electrical resistance drops sharply to zero when their temperature is lowered below it's critical temperature ($T_c$), There are two types of superconductors $\mathrm{Type\text{ }I}$ and $\mathrm{Type\text{ }II}$. Type I Superconductors: In $\mathrm{Type\text{ }I}$ superconductors ...

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The induced current will flow in such a way that the flux produced will tend to cancel the change in flux. According to traditional classical electrodynamics, the magnetic field does not do any work and it is the electric field and the charge carriers which do the work and ultimately limit Faraday's law in extreme cases.

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A fermion is just a particle of half-integer spin. Being a lepton for a particle is a matter of definition of global symmetries of the theory. This means that a lepton can in principle be both a fermion or a boson, although all known leptons are fermions (electron, muon, tau and their neutrinos). One example of bosonic lepton is the weak triplet Higgs ...

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A fermion is any particle, elementary or composite, that obeys Fermi-Dirac (as opposed to Bose-Einstein) statistics relating to how identical particles behave when you swap two of them. Due to an important but complicated result, this is taken to amount to having half-integer spin. A lepton is one type of elementary particle with spin 1/2. The only leptons ...

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A fermion is any particle characterized by Fermi–Dirac statistics and obeying the Pauli exclusion principle. So for example quarks are fermions, as are Helium-3 atoms. A fermion does not have to be an elementary particle. I'm not even sure that it has to be spin $\tfrac{1}{2}$, though I can't think of any fermions that aren't. A lepton is a spin ...

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The Standard Model includes 12 elementary known as fermions that respect the Pauli exclusion principle. They include six quarks (up, down, charm, strange, top, bottom), and six leptons (electron, electron neutrino, muon, muon neutrino, tau, tau neutrino) (ref) All leptons are fermions, but not all fermions are leptons.

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The short answer is that BCS theory is derived bottom-up from quantum mechanics (you assume that there is some local attractive interaction between electrons, and perform a mean field approximation), while the older Ginzburg-Landau theory is derived top-down from thermodynamics (you assume that superconductivity can be described by some order parameter, and ...

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This is actually exactly the same question I was asking myself a while ago, and it took me quite some time to figure it out. What I ended up doing was: diagonalise the BdG Hamiltonian in Mathematica solve the expressions for the eigenvalues for $\kappa$ neglect terms proportional to $\kappa^2$, $\kappa \Delta$ in the expressions for the eigenvectors, ...

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Can someone help provide me with an argument why the electric field must be zero in a perfect conductor? It's not clear exactly what you're looking for. In a sense, any argument attempting to prove that the electric field must be zero in a perfect conductor will beg the question. For example, here's an excerpt from "Electromagnetics for High-Speed ...

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That's probably (one of) the biggest open question in condensed matter physics. High-T superconductivity is microscopically not well understood. Apparently, reduced dimensionality (CuO2 sheets in YBCO), interplay with magnetism (ground state tends to be antiferro magnetic), quantum fluctuations of spins, and other exotic concepts are parts of their ...

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The electrical field $\mathbf{E}$ is an external field, which "drags" the conductor electrons through the conductor "lattice". The conductivity $\sigma$ describes the resistance of the "lattice". When the resistance is zero, a non zero current can exist in the conductor without necessity to support it with an external field. If $\mathbf{E}$ is non zero, the ...

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