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.

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  1. G

    B Why is my small Bi-2223 superconductor not levitating or locking above magnets?

    I am a supervisor for a student's high school project. He has acquired a small superconductor of Bi-2223, specifically this one: https://shop.can-superconductors.com/hts-demo-parts/11-superconducting-bi-2223-bar The superconductor is just a couple of centimeters long and a few millimeters wide...
  2. StanislavD

    A Decay of supercurrents connected to non-superconducting zones?

    This question is more complicated than it seems, most physicists cannot answer it unambiguously and there is no experiments to the issue. Imagine, a persistent supercurrent flows in a SC aluminum ring. Then we connect the SC aluminum ring (without solder) to an aluminum wire, the second end of...
  3. BWV

    Room temperature superconductor paper published

    This paper is circulating around fintwit , has not been replicated, but does it pass a smell test? https://arxiv.org/abs/2307.12008 The First Room-Temperature Ambient-Pressure Superconductor Sukbae Lee, Ji-Hoon Kim, Young-Wan Kwon
  4. sol47739

    I Can Superconductors Reach Relativistic Speeds and Emit Synchrotron Photons?

    How are currents injected into a superconductor? And can you regulate the velocity of the current afterwards? Since the magnetic field can’t penetrate? What would happen if you tried to make the Cooper pairs approach relativistic speeds? Would the superconductor stop being in its...
  5. sol47739

    I Superconductors and moving/accelerating charges

    How do one get the electrons to move inside a superconductor? Since I have understood superconductors repel magnetic fields due to the Meissner effect, or is that when the charges already are moving within the superconductor? If so how did we get them o move from the beginning? Can you make...
  6. SBrownJC

    EE: How to heat a magnet with a wire while levitating a superconductor?

    Hi I'm doing my extended essay (like a research paper) for the IB and I'm having a bit of trouble with my setup and data process. The plan for my experiment goes something like this: I have a magnet wrapped in wire strapped to a battery and a superconductor in liquid nitrogen. After levitating...
  7. Faizan Samad

    I Why does doping make resonating valence bonds (singlet pairs) mobile?

    I know in RVB theory that neighbouring Copper atoms form singlet pairs via the superexchange "force". Upon doping with holes, these neutral singlet RVB pairs become mobile and charged and are able to superconduct. I know that the resonating valence bonds are in the copper 3d(x^2-y^2) orbital and...
  8. VictorMedvil

    A What Superconductor Can Have The Highest Magnetic Field Strength?

    Hello, I asked a question about superconductors in 2020 and I was now wondering what superconducting chemical/material can have the highest magnetic field strength before the superconductivity is destroyed by it? Secondly, What the is maximum magnetic field strength of said material in Tesla per...
  9. patric44

    Gibbs free energy for superconductor in intermediate state

    hi guys I am trying to derive the Gibbs free energy for a superconductor in the intermediate state , the book(Introduction to Superconductivity by A.C. Rose-Innes) just stated the equation as its : $$ G(Ha) = Vgs(0)+\frac{V\mu_{o}H_{c}}{2n}[H_{a}(2-\frac{H_{a}}{H_{c}})-H_{c}(1-n))] $$ I am not...
  10. A

    A Superconductor ring: shielding currents in different directions

    In this photo you see on the right-hand side that the outer wall current is negative and the inner wall current is positive. That is, they are directed in different directions. But if the applied magnetic field is in the z direction as shown, then shouldn't they both be in the same direction do...
  11. B

    Superconductor Flux pinning/Meissner effect with electromagnets?

    I was reading about high temperature superconductors expelling magnetic fields (Meisner effect). I was curious if this only works with permanent magnets or is there similar effects with electromagnets. I assume since the magnetic waves would be similar there would be a similar reaction, but...
  12. A

    A Superconductor in a hollow cylinder -- two different end states. Why?

    When a magnetic field is applied to a SC during cool down, the field goes through the hole of the hollow cylinder. When the cool down first takes place and then later a magnetic field is applied, the magnetic field does not go through the hole of the hollow cylinder but rather is expelled to the...
  13. N

    I What happens to the temperature of a superconductor?

    Consider the following setup: Stationary magnet and Superconductor are fixed and Moving magnet is allowed to move freely in the horizontal direction. Assume the superconductor as Type I superconductor. Following figure shows the Horizontal Force acting on Moving Magnet vs Distance curve...
  14. dRic2

    I Electric field inside a Superconductor

    I was reading chapter 3 of this book https://blackwells.co.uk/bookshop/product/Superconductivity-by-James-Arnett/9780198507567, which is a brief introduction to superconductivity. It is stated that inside a superconductor the Electric filed is always zero. This is deduced from the equation...
  15. K

    AC superconductor transmission

    For underground AC transmission, the line charging current prevents the lines from exceeding 100 km due to the close proximity and high capacitance between the line and ground. If the line was made with superconducting material, I think the same distance limitation applies (assuming same power...
  16. Dante Meira

    Can a superconductor "repel" an electromagnet due to the Meissner effect?

    A superconductor with little or no magnetic field within it is said to be in the Meissner state. The Meissner state breaks down when the applied magnetic field is too strong. But what happens if an electromagnet that is at first "turned off" is suddenly "turned on", in the close proximity of a...
  17. pangru

    Physics Career in cuprate high temperature superconductor physics

    Hello, I am interested in physics of cuprate high temperature superconductors (Cuprate_SC) However, I heard that it is "out-of-dated" topic in solid state physics and almost impossible to find group/foundation to do research in this field. I am doing PhD right now and I consider moving...
  18. F

    What is the maximum current in a superconductor loop?

    If we put an emf equal constant onto a superconductor loop(we consider the resister of emf equal zero), then what is the maximum of current in the loop?
  19. cynth

    A Electronic band structure of iron superconductor BaFe2As2

    how can I determinate the electronic structure of a multiband system? for example in the case of the superconductor BaFe2As2 , the electronic properties are as known dominated by 5 Fe d states at the fermi energy, so 5 bands cross the Fermi level and form 5 Fermi surface sheets (if we consider...
  20. K

    I Equation for levitation forces between the magnets and superconductor

    How can I measure the levitation forces between the magnets and a type-II superconductor (YBCO superconductor)?
  21. I

    Why does a magnet above a superconductor stop spinning?

    I got the opportunity a while ago to play around with a magnet floating above a superconductor cooled with liquid Nitrogen. The magnet was a little cube, and I spun it with a pair of tweezers. I was surprised at how quickly it stopped spinning, it seemed to stop much quicker than could be...
  22. .Scott

    B Superconductor at 250K, 170GPa

    I have actually been outside when the temperatures dipped below 250K. Although the pressure wasn't 170GPa. The discovery is being reported in arXiv here: https://arxiv.org/abs/1812.01561 PDF: https://arxiv.org/ftp/arxiv/papers/1812/1812.01561.pdf It looks like most of the work was done out...
  23. Raihan amin

    Superconductor in an external magnetic field

    Homework Statement A superconducting spherical shell of radius R is placed in a uniform magnetic field ##\vec{B_0}## 1)Find the magnetic field everywhere outside the shell 2)the sutface current density Homework Equations Inside the shell the net magnetic field is 0, and at the surface also...
  24. YoungPhysicist

    I Space docking using the Meissner effect

    Just a random thought: IF a strong rare Earth magnet and a superconductor like YBCO can perform meissner effect that holds them both in place, is it possible to make that in a larger scale, like in space? I was thinking that since space's temperature is almost 0K, it can cool down...
  25. li dan

    I Stress problem between superconductor and wire

    In superconducting state, If the superconductor and the guide line are stationary, will the force between the the guide line and the superconductor change when they are close to or far away from the magnet?
  26. li dan

    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 indicating position? Or is there no change in the intensity of the magnetic field that belongs to...
  27. S

    Phase transitions in a superconductor

    Homework Statement The phase transition to a superconducting state moves to lower temperatures as the applied magnetic field, H, increases. The magnetic moment, M, for a system of volume V is given by: $$M=-\frac{HV}{4\pi}$$ for ##H<H_C(T)## (superconducting) and $$M=0$$ ##H>H_C(T)## (normal)...
  28. R

    Why does the Japanese Maglev train use superconducting magnets

    My little home made air-core solenoid makes 1.5T, why is it that superconducting electromagnets often aren't stronger than one would expect. Take the japanese maglev train for example: http://www.supraconductivite.fr/en/index.php?p=applications-trains-maglev-more According to this article the...
  29. B

    B What does the levitating frog feel?

    If you were suspended inside and iron armor between an electromagnet and the ground it is obvious that you would feel your weight against that armor, but when a frog is suspended by diamagnetic levitation I understand that it feels weightlessness. If this is correct, that means that if it were...
  30. DeathbyGreen

    A Zero Energy Wavefunctions in 1D superconductor

    \bf{Setup} Hi! I am trying to derive the wavefunctions of the zero energy solutions of the Schrodinger equation in a 1D p-wave superconductor (Kitaev model). I am starting with the Hamiltonian $$ \begin{equation} H = \left[\begin{array}{cc} \epsilon_k & \Delta^{\ast}_k\\ \Delta_k & -\epsilon_k...
  31. John Morrell

    How are Superconducting Coils charged?

    Superconductors can be used to store energy in the form of magnetic fields, because the current in a superconductor can persist indefinitely. In fact, some large power grids are already using this as a way to regulate power flow in the grid. My question is how are the coils "charged"? How do we...
  32. John Morrell

    I Limits to Superconductor Energy Storage?

    I'm just starting to learn about the physics behind Faraday's laws and magnetic flux and it's gotten me thinking a lot about superconductors. I know that you can store energy in a superconductor in the form of magnetic fields since a current in a superconducting loop will persist indefinitely...
  33. G

    Self inductance of a superconductor

    Hi. Superconductors can be made hover above or even below magnets. As far as I know, this can be interpreted as an extreme form of Lenz's law: Eddy currents on the surface of the superconductor create an opposing force that is able to cancel gravity since the currents aren't affected by...
  34. I

    Other Superconductor book for starter?

    I got interested in this superconductor stuff a few week ago and I just want to learn more about this. So any book or ebook recommendation about superconductor ? especially for starter ? Note: I'm a new engineering student
  35. D

    I Superconductor momentum conservation

    I often hear that a superconductor can hold a current indefinitely, I have a thought experiment which relates to this claim. Consider a closed square loop of superconducting wire, this wire carries some current. Will the electrons in the circuit transfer momentum and energy to the metal lattice...
  36. S

    Relativistic electron Moving through toroidal superconductor

    I understand the electron in the situation to be rapidly accelerated away from the torroid. If this is true, my question is: Will the electron emmit radiation following the synchrotron formula? Also, would the radiation travel through the torroid?
  37. Electron Spin

    Quantum obstacle course changes material from superconductor to insulator

    "a material to conduct an electrical current with zero resistance" ? Is this not ohm's law to a logical extreme?, or am I missing something?
  38. Johnny_Sparx

    A Numerical Solution for Complex PDE (Ginzburg-Landau Eqn.)

    I am looking to numerically solve the (complex) Time Domain Ginzburg Landau Equation. I wish to write a python simulator to observe the nucleation of fluxons over a square 2D superconductor domain (eventually 3D, cubic domain). I am using a fourth order Runge Kutta solver for this which I made...
  39. D

    I Difference between Zero-Field Cooling and Field Cooling

    I am currently doing a experimental project work on superconductors. I am supposed to study properties of FeTeSe. I am having trouble understanding the difference between Zero-Field Cooling and Field Cooling. In both cases, I am measuring magnetization with varying temperature (from lower to...
  40. Z

    A Does a type I superconductor have to be single crystal?

    Does a type I superconductor has to be single crystal? If not, is there any change in its Tc when it becomes polycrystal? Thanks.
  41. F

    Superconductor structure and contents

    Hi. What are superconductor ions? Are they naturally occurring ions inside the lattice structure of a superconductor when it's manufactured or are they ions introduced artificially to a superconductor's lattice ? And do the ions have spin?
  42. F

    Organic Superconductor: Advantages Over Conventional & High Tc

    What is the advantages of organic superconductor rather than konvensional and high Tc superconductor? Thanks
  43. S

    Creating YBCO: Melting Down and Doping for Superconductivity

    Once synthesized, can YBCO be melted down to add more material or change the doping and still result in a functional superconductor?
  44. T

    What effect would one expect if the Critical Temperature is

    The measurement of electrical resistance as a function of the superconductor's temperature yields fundamental insights into its properties. The Critical Temperature, Critical Current Density, and the Critical Magnetic Field, can all be obtained through variations of a basic experiment. I would...
  45. T

    Buy Small Superconductors Online | Explore the World of Superconductivity

    Hello, I have been looking at superconductors lately and was wondering if there was anywhere I could get a small superconductor online. I realize for it to actually conduct it must be incredibly cold, but I was wondering where I could get a metal that allows for superconduction.
  46. C

    Where can I get a cheap ceramic (hi temp.) superconductor?

    I used to have one for demonstration...need to find a current source ...maybe a small 1 inch diameter disk...or preferably a ring. Any sources? Thx.
  47. I

    Force on a superconducting cube

    Hi everyone, I need some help to look if I did these calculations right.Let us assume a three dimensional magnetic field: ##\vec{B}(x,y,z) = B_x(x,y,z)\hat{x} + B_y(x,y,z)\hat{y} + B_z(x,y,z)\hat{z}## The equation for the force on a superconducting particle in a magnetic field is given by...
  48. B

    Gibbs and Helmholtz energies of a superconductor

    Hello, I consider an ideal superconductor with the gibbs-energy $$ d G=-SdT + VdP - \mu_0 M V dH$$ and helmholtz energy $$ dF = -SdT -P dV + \mu_0 V H dM$$ Assuming, that in the normal state the magnetization is too small, so that G_n(H) = G_n(H=0) and at the transition point H_c the...