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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.

Superconductivity is the transmission of current with no resistive losses, and is one of the most active areas of condensed matter physics research.

Superconductivity was first observed by Kamerlingh Onnes in 1911 when he discovered that the resistivity of mercury went to zero at 4.2K. Since that first discovery, superconductivity has been found in a wide variety of material classes, from pure elements to complex structures like cuprates, organometallics, and heavy fermions. The current record for high temperature superconductivity is close to 150K, which is found in a cuprate compound at high pressure.

Important outstanding questions in superconductivity research remain the origination of the pairing mechanism for unconventional superconductors, and whether room temperature superconductivity is possible.

There are many web resources for superconductivity. General introductions to the topic may be found in the following web sites: Hyperphysics: http://hyperphysics.phy-astr.gsu.edu/hbase/solids/scond.html Wikipedia: http://en.wikipedia.org/wiki/Superconductivity

The current research edge of the field may be found on the arXiv preprint server, which has an entire subsection devoted to superconductivity research: http://arxiv.org/list/cond-mat.supr-con/recent

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Is an electron a superconductor?

A superconductor has zero resistance. What about an electron in a vacuum? Could this simple system be considered superconducting?
Alex
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Intuitive reasons for superconductivity

Superconductivity I read in a book "Physics - Resnik and Halliday" the explanation of Type-I Superconductors {cold ones} that: The Electrons that make up current at super-cool temperatures move in coordinated pairs. One of the electrons in a pair…
The-Ever-Kid
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What is the RC time constant in a superconductor?

In conventional conductors, the RC time constant is the time required to charge or discharge a capacitor through a resistor by ≈ 63.2 percent of the difference between the initial value and final value: $$\tau = R \cdot C $$ However, in a…
travisbartley
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Why do superconductors have a maximum current density?

If superconductors have no resistance, what prevents you making the cross-section as small as you can handle, if there will be no power dissipated anyhow? Is there a limit on the magnetic field that the superconductor can contain, if there is no…
hifkanotiks
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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 above temperature is the maximum critical…
Pie86
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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-temperature superconductivity (HTS). Is there any HTS…
leongz
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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 / normal? Would this be gradual across the wire,…
sci-guy
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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_{-k\downarrow}^{\dagger}\right)…
smheidrich
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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 superconducting order parameters. Where does this phase…
ChickenGod
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London penetration depth

Which type two s-wave superconductor has the smallest London penetration depth? What is l_lamda ?
user2553
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Why do Cooper pairs not bump into other particles?

I sort of get how they get formed and how it works but why do they not bump into other particles? and do the spins have to do with this?
user106621
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Pairing symmetry / superconducting gap symmetry

I'm not (yet :-) ) an expert on superconductors, but one term I keep hearing all the time is that of the symmetry of the gap, which can be s-wave, p-wave, d-wave etc. What exactly is the symmetry this refers to? I guess "something" will have…
Lagerbaer
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Supercurrent dynamics

I was trying to explain the dynamics of a DC current in a superconductor -- for example, a ring -- and was asked, essentially, Cooper pairs are the charge carriers, are all in the same state, and cannot scatter. Well how do they "change direction"…
Tejas Guruswamy
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Can a very small piece of material be superconducting?

The existing theory of superconducting seems to be based on statistical mechanics. Can an ultrasmall piece of material, like a quantum dot with very few atoms (like a small molecule), be superconducting? For example, can a cubic of 3 * 3 * 3 = 27…
jw_
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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 effect, expulsion of magnetic fields from the…
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