What is Superconductor: Definition and 149 Discussions

Superconductivity is a set of physical properties observed in certain materials where electrical resistance vanishes and magnetic flux fields are expelled from the material. Any material exhibiting these properties is a superconductor. Unlike an ordinary metallic conductor, whose resistance decreases gradually as its temperature is lowered even down to near absolute zero, a superconductor has a characteristic critical temperature below which the resistance drops abruptly to zero. An electric current through a loop of superconducting wire can persist indefinitely with no power source.The superconductivity phenomenon was discovered in 1911 by Dutch physicist Heike Kamerlingh Onnes. Like ferromagnetism and atomic spectral lines, superconductivity is a phenomenon which can only be explained by quantum mechanics. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor during its transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics.
In 1986, it was discovered that some cuprate-perovskite ceramic materials have a critical temperature above 90 K (−183 °C). Such a high transition temperature is theoretically impossible for a conventional superconductor, leading the materials to be termed high-temperature superconductors. The cheaply available coolant liquid nitrogen boils at 77 K, and thus the existence of superconductivity at higher temperatures than this facilitates many experiments and applications that are less practical at lower temperatures.

View More On Wikipedia.org
Recent contents Top users
  1. E

    Explaining the Absence of Band Gaps in Superconductors

    Hi all, I am currently writing a report about superconductors, and am currently reading about how the band gap shows that single electrons are not the charge carriers responsible for superconductivity. However, I was confused when I read that electrons are fermions and as such there are no band...
  2. Alex299792458

    Can electricity in a superconductor make a magnetic field?

    So since a lot of electricity ran through a coil creates a magnetic field as sown in one of faradays most famous experiment what if the coil was a superconductor and will it improve the magnetic field and will it make one at all?
  3. S

    YBCO Phonon Frequency: Hole Doping .2, 75-70°K @ 70°K

    I was hoping someone could tell me the phonon frequency of the electrons for YBCO with hole doping of about .2 and a critical temperature of around 75-70°K at about 70°K. An answer in Hz would be preferred, or failing that, in cm-1 with the wave speed. Also, might the Kohn anomaly influence the...
  4. Eddie Sines

    What are the fine details of Type II superconductors?

    Independent research person who is working with Type II Superconductors. Would enjoy talking with fellow research people to discuss the fine details of Type II materials, specifically electrons and energy.
  5. D

    Surface Barrier in Type 2 Superconductors

    If a field line is moved into a superconductor it meets resistance. This resistance is modeled by adding an image flux thread outside the superconductor which then attracts the flux thread being moved into the superconductor. Why is this attractive force an accurate model of the resistance a...
  6. R

    Basis Atom of Superconductor

    Hi everyone, I'm trying to simulated the XRD pattern of Bi2Sr2Ca2Cu3O10, but I'm having a problem of finding the basis of atom(and their respective position). Also its JCPDS is quite hard to find, so if anyone working with this, may you provide a link or articles about my problem. Thanks...
  7. L

    Magnetic susceptibility of Superconductor

    as we know, B=0 in superconductors, because of Messner effect. B=μ0(H+M) => H=-M => χ=-1 in CGS units: B=H+4πM => H=-4πM χ=-1/4π --- question: why χ=-0.01 not χ=-1/4π for 100% superconductors? :frown::oldshy:
  8. Jackson Lee

    A question about electromagnetic induction

    Hey, guys, I encountered this and confused about it. "In a perfect conductor, an arbitrarily large current can be induced, and the resulting magnetic field exactly cancels the applied field." But I suppose, according to Faraday's law,the magnitude of emf is the rate of change of magnetic flux...
  9. T

    Gibbs Free Energy in Superconductors

    When reading some material concerning Ginzburg-Landau theory of superconductors, I got the following sentence: The appropriate thermodynamic potential for describing a superconductor in an applied magnetic field is the Gibbs free energy ##G## (natural variable ##H##) and not the Helmholtz free...
  10. A

    What can be found in the MT curves of superconductors?

    I am confused about the magnetic susceptibility vs. temperature curves (or MT) of superconductors (SCs). In the normal conduction state (I measured from 4.5K to 300K), the susceptibility curve can obey the Curie-Weiss law. But when I fitted the data via the Curie-Weiss law in a different...
  11. C

    Superconductor science fair project?

    I'm thinking of doing a science fair project having to do with a superconductor. However, the problem is that I have two things I don't understand, exactly what the science fair is asking for, but that's okay, I can always ask my teacher- And also, how I should start with this superconductor...
  12. K

    Is Superconductivity Related to the Qualities of Outer Space?

    From what i have read on super conducting materials they require extremely low temperatures and that the structure of them becomes altered so that the atoms form a sort of uniform tube instead of more like a mesh pattern. Ie the atoms do not intefere with the passage of electrons/photons...
  13. T

    Can BCS theory explain type-II superconductor?

    I know that BCS theory cannot explain high Tc superconductor. Most high Tc superconductors belong to type-II ones. Can BCS theory explain type-II conventional superconductor? How to predict high Hc2 and low Hc1 for type-II conventional superconductor in BCS theory?
  14. J

    Remotely changing superconductor levitation height

    Forgive me if some of my question sounds misguided or misinformed - I'm new to the flux pinning game. I want to be able to modify the height of a quantum locked superconductor. My original plan was to levitate the superconductor over an electromagnet and modify the current to said magnet...
  15. Salvador

    Understanding the Working of Superconductors and Ordinary Conductors - Explained

    Hi, I did a forum search on the topic , but from all the threads I went through I still have doubts about my understanding , please correct me. Both superconductors and ordinary conductors are metals or metal alloys.Both have ion lattice and electrons that are the moving , current , heat...
  16. L

    Calculating power in a superconductor

    I see in the main page an article touting a record setting 20,000 amps flowing in a superconductor. Normally, with resistance in the circuit, it is a simple matter to multiply volts times amps to come up with watts or joules/second. But in a superconductor the resistance is zero so 20,000...
  17. L

    Superconductor coherence length and penetration depth

    Homework Statement I have a lot of information about 2 different superconductor materials; indium and lead. The indium is pretty much 100% indium with no impurities, and the lead is unknown purity. I have the temperatures and magnetic fields at which they are superconducting and the...
  18. K

    High-Temperature Superconductor Transport

    I am starting to work with the high temperature superconductor BSCCO (Bi–Sr–Ca–Cu–O). I have read that the carriers of superconducting current is hole pairs. (As opposed to electron-pairs in normal superconductors) I am trying to understand how the transport would work. If I contact it with...
  19. J

    Superconductor dark matter detection?

    Sorry - a very vague question: Could a superconductor be used to detect dark matter? The dark matter might interact with electrons in the superconductor giving them some momentum. These moving electrons would constitute a supercurrent which could be measured - maybe! Perhaps the...
  20. A

    Superconductor: Magnetic Field Strength VS distance

    Hi all, Does anyone know how the magnetic field strength of a superconductor varies as distance from the outside of the superconductor? Aside from a superconductor being able to creates a stronger magnetic field than a regular dipole, does the strength still go down as 1/r^2 or does it...
  21. A

    Connect an ideal battery across two end of a superconductor?

    Hi, What will happen if I connect an ideal battery across two ends of a superconductor? Assume all contacts are ideal, lossless. Is the current infinitive?
  22. K

    Mass of a permanent magnet levitating a superconductor?

    If you were to levitate a superconductor using a permanent magnet due to the effects of the Messiner Effect, and you were then to lift the permanent magnet with your own hands, would you be lifting the mass of the permanent magnet, the mass of the permanent magnet + the mass of the...
  23. V

    Superconductor Ginzburg-Landau model

    Homework Statement Why is it that for a superconductor \alpha<0,\beta>0 in the Ginzburg-Landau model wit free energy formulation E=\int d^3x\,\, \frac{\vec B^2}{2\mu}+\frac{1}{2m}|(-i\hbar\nabla-e\vec A)\psi|^2+\alpha|\psi|^2+\beta|\psi|^4 Homework Equations E=\int d^3x\,\, \frac{\vec...
  24. M

    What materials can be used as a superconductor?

    Hey guys! I'm doing a science project on high temperature superconductors and i was just wondering, what kind of metals that can be bought will become a superconductor when put in liquid nitrogen. Liquid nitrogen of course is 63k so anything below 63 kelvins will not work, however if a metal...
  25. A

    : solenoid and superconductor questions

    URGENT: solenoid and superconductor questions Sorry I cross posted this, but I realized that general physics was probably a better place for it... I have a few questions regarding the levitation of a piece of superconductor using the field from a solenoid. In other words, I want to calculate...
  26. Y

    Amount of flux lines 'pinned' in type II superconductor

    a type II superconductor may not exhibit complete exclusion of magnetic field due to quantum vortices. It is my understanding that the magnetic field present will affect the number of vortices or fluxons present, but what is the relationship between magnetic field, and number of vortices in a...
  27. T

    Deriving the London's equation for superconductor

    The equation can be obtained from the fact that the "canonical momentum of the ground grstate of superconductor is zero", but where does this fact follow from. P.S. Jackson gives a vague reference to Kittel, which I couldn't find in his Introduction_to_solid_state/Quantum_theory_of_Solids.
  28. P

    Maximum current a superconductor can carry

    Homework Statement Niobium metal becomes a superconductor when cooled below 9 K. Its superconductivity is destroyed when the magnetic field inside the superconductor exceeds 0.100 T. Determine the maximum current a 3.00-mm-diameter niobium wire can carry and remain fully superconducting, in...
  29. T

    Understanding Resistivity in Superconductors

    What is the Resistivity of YBCO in superconductive state because it is not zero, or there would be not heat created so what is it or am I wrong? Explain to me where the heat from a current passing into a superconductor comes from.
  30. L

    Why is the magnetic field of a superconductor normally excluded?

    Why is the magnetic field of a superconductor normally excluded?
  31. L

    How Do Superconductors React to External Electric Fields?

    A magnetic field is excluded in a superconductor so what happens to its electrical counterpart? Does it also become excluded? How do superconductors respond to external electric fields?
  32. L

    How Can I Find the Chemical Hg12Ti3Ba30Ca30Cu45O125?

    Does anyone know how one might obtain a chemical called "Mercury Thallium Barium Calcium Copper-Oxide"(Hg12Ti3Ba30Ca30Cu45O125)? I searched online, but I couldn't find any vendors.
  33. X

    Superconductor that is superconductive at room temperature

    What's the possibility of developing a superconductor that is superconductive at room temperature? Developing such superconductor would be a very significant scientific advancement and will certainly change out lives.
  34. V

    Conservation of current in superconductor

    Hello, I wonder: 1-) whether the (Cooper pair) current is conserved in a superconductor? 2-) and, how I can see it mathematically? 3-) are there any differences between the London theory and the BCS theory in regard to current conservation. I would appreciate any comments on these...
  35. leviterande

    The repelling force of a superconductor how strong?

    Hi, I posted this earlier in what I thought to be the "General Physics" section, but since it got deleted and I was notified that I posted in "GD" which is (general discussion?) I realized I did this by mistake so I am sorry. -------------------------- to my question Hi, What I...
  36. H

    Superconductor in vacuum chamber - low energy consumption solution?

    Hello all, Superconductors are great, but obviously its tricky to keep them at such a low temperature for extended periods of time. This poses a problem for engineering applications. What about the feasibility of cooling the superconductor, then placing the material in a vacuum chamber...
  37. C

    Measuring resistance in a superconductor

    I am currently an intern at a superconductor lab and have been faced with a personal curiosity. I work with a device that determines the critical temperature at which the material stops superconducting. This device is composed of an electric temperature probe and two coils of wire which are...
  38. J

    Are the weak force bosons truly short ranged or do they acquire mass?

    As I understand it in a normal superconductor electromagnetic fields are extinguished by opposing fields produced by induced superconducting currents. This causes photons to only penetrate a short distance into a superconductor. I understand that one can imagine the Higgs field as a kind of...
  39. D

    Room temperature superconductor

    Theoretically, if I had my usual, cheap, room-temperature superconductor :smile:, what could I do with it?
  40. C

    Motion of cooper pairs in superconductor

    I have learned that as temperature decreases, the motion of particles in a lattice decreases.Then how can a cooper pair move so swiftly across the lattice when temperature is considerably low?Can anyone please explain?
  41. J

    Permanent magnet trapped inside a superconductor

    I was wondering what it would be like if you had a permanent magnet inside the core of a material capable of obtaining the superconducting state. And you cooled it down so that it becomes a superconductor. Assuming it didn't explode; would it just condense the magnetic field into some...
  42. B

    AC magnetic field applied to a superconductor, London Theory

    Hey all, I'm just working through the london theory of superconductors. I've dervied the london penetration depth, the distance for the amplitude to drop by a factor of 1/e... Seems simple... Now my book talks about applying a an ac magnetic field to a superconductor. How would the field...
  43. I

    Flux tubes in a Type II Superconductor

    What would happen if a magnetic field is generated inside of a Type II superconductor? Would there be flux tubes?
  44. H

    What is the role of coercivity in modeling superconductors in Opera v15?

    I am modeling a magnetic coil array in Opera v15. My current project uses a CosΘ Coil inside a Metglas cylinder (Ferromagnetic) inside a Pb cylinder (Superconducting) at 4ºK. The method used to specify the a material in Opera is to specify the Coercivity and Relative Permeability. If I had...
  45. W

    Exploring Superconductors: Effects of Broken Samples and Levitation Distance

    Hello! Me and some friends are doing a phyics project at school. The theme is superconductor. The school have a superconductor, but its broken i half (like two half moons). My question is: will this effect the result? And does the thickness matter how far above the surfice it will levitate...
  46. C

    Thermal Superconductor Design: Possible?

    Go easy on me, as I have no formal condensed matter education and just the highest undergraduate quantum physics and chemistry offered at my university. I read a lot of papers and did extra studying while taking those classes, but I'm definitely rusty on the mathematics. Feel free to give me...
  47. L

    Superconductor dust levitation in the Earth's magnetic field

    In the wake of recent metallic hydrogen news, and the fact that metallic has long been thought to be a room temperature superconductor, I began to ponder about the age old question of superconductor levitation. Now that we are no longer restricted by temperature requirements, perhaps levitation...
  48. M

    A type 2 superconductor is placed in a small magnetic field

    A flux quantum is approx. equal to 2*(10)^(-7) gauss cm*cm. A type 2 superconductor is placed in a small magnetic field which is then slowly increased till the field starts penetrating the superconductor. THe strength of the field at this point is 2/pi*(10)^(5) gauss. The penetration depth...
  49. jaketodd

    Spinning Superconductor Questions

    If someone(s) would be so kind, I have some complicated curiosities about spinning superconductors. This is not homework. What types of materials can a spinning superconductor lift? Does it only work against gravity, or can it work in any direction? Does it have to be cooled? How much...
  50. K

    Falling superconductor in a magnetic field

    Hello. Recently I have been inspired by the classic "drop a NdFeB magnet down a copper tube" demonstration, and I have been thinking about a superconductor falling in an ambient magnetic field. I want to determine the terminal velocity, if one exists. Now, I'm interested only in the effect...
Back
Top