What is Meissner effect: Definition and 43 Discussions

The Meissner effect (or Meissner–Ochsenfeld effect) is the expulsion of a magnetic field from a superconductor during its transition to the superconducting state when it is cooled below the critical temperature. This expulsion will repel a nearby magnet.
The German physicists Walther Meissner and Robert Ochsenfeld discovered this phenomenon in 1933 by measuring the magnetic field distribution outside superconducting tin and lead samples. The samples, in the presence of an applied magnetic field, were cooled below their superconducting transition temperature, whereupon the samples cancelled nearly all interior magnetic fields. They detected this effect only indirectly because the magnetic flux is conserved by a superconductor: when the interior field decreases, the exterior field increases. The experiment demonstrated for the first time that superconductors were more than just perfect conductors and provided a uniquely defining property of the superconductor state. The ability for the expulsion effect is determined by the nature of equilibrium formed by the neutralization within the unit cell of a superconductor.
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. Superconductors can be divided into two classes according to how this breakdown occurs.
In type-I superconductors, superconductivity is abruptly destroyed when the strength of the applied field rises above a critical value Hc. Depending on the geometry of the sample, one may obtain an intermediate state consisting of a baroque pattern of regions of normal material carrying a magnetic field mixed with regions of superconducting material containing no field.
In type-II superconductors, raising the applied field past a critical value Hc1 leads to a mixed state (also known as the vortex state) in which an increasing amount of magnetic flux penetrates the material, but there remains no resistance to the electric current as long as the current is not too large. At a second critical field strength Hc2, superconductivity is destroyed. The mixed state is caused by vortices in the electronic superfluid, sometimes called fluxons because the flux carried by these vortices is quantized. Most pure elemental superconductors, except niobium and carbon nanotubes, are type I, while almost all impure and compound superconductors are type II.

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  1. 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...
  2. M

    I General relativity - covariant superconductivity, Meissner effect

    I am doing a project where the final scope is to find an extra operator to include in the proca lagrangian. When finding the new version of this lagrangian i'll be able to use the Euler-Lagrange equation to find the laws of motion for a photon accounting for that particular extra operator. I...
  3. Narayanan KR

    Magnetic Permeability: Temperature Effects

    One more thing i forgot to add, is magnetic permeability of a metal constant irrespective of its temperature including superconducting temperature ?
  4. 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...
  5. 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...
  6. T

    B What exactly causes the Meissner effect

    I've read about the Meissner effect, it seems to suggest that a magnetic field passing through an object gets ejected/repelled (is that the right phrase to use?) from the object after said object has surpassed the critical temperature (i presume pressure as well?)... but what's actually...
  7. 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)?
  8. K

    B I formulating a research question for my Extended Essay

    Hello, I am a student in the IB Diploma course. I've decided to focus my essay on quantum locking: including superconductors (YBCO), the Meissner Effect. I have access to the materials needed to experiment with this topic (materials from quantumlevitation.com). Could anyone help me formulate an...
  9. 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...
  10. 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?
  11. 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...
  12. li dan

    Can an aircraft using a geomagnetic field generate lift?

    As shown in the figure, the aircraft includes a geomagnetic field convergence layer, which is a superconductor material. The geomagnetic field convergence layer repels the direction of changing the geomagnetic field, so that the geomagnetic field passes between the upper and lower converging...
  13. M

    Fun magnetics question with the Meissner Effect

    I was hoping I could get some help deriving a formula that shows how much current is needed to generate enough of a magnetic field to lift an X Newton mass L meters above a superconductor. ( Probably in centimeters but meters here for the sake of SI easiness ) I was helping one of my professors...
  14. G

    I Delay in normal-to-Meissner state

    If we switch a super-conductor between normal and Meissner states, using varying magnetic field, there has to be some delay from when the field exceeds the critical field to the appearance of Meissner state. Have there been any experimental measurements of this delay? What are the measured values?
  15. R

    I Superconductors and the Meissner effect

    So I am writing a paper on superconductors, and i am trying to explain the meissner effect. However i seem to be running into conflicting information. I hoping some one can help clarify. The effect happens, when a magnet creates a change in flux, causing a induced current in the...
  16. O

    Meissner effect and future application to the hoverboard -- Ideas?

    I'm working on a project of magnetic levitation of the lexus hoverboard Which is based on Meissner effect and suprconductivity and I have to look for contraint, probability, choice, and optimization in this project, i really find a little bit tough where to start this, so if anyone have any...
  17. J

    B Superconductivity & the Meissner Effect

    Hi, I am new to superconductivity and have been doing a lot of reading to try and become familiar with it. I have come across a few questions that I would be grateful is someone could answer. I am confused about the mechanism that describes the expulsion of magnetic fields from inside a...
  18. N

    Difference between Superconductivity & Ballistic Conduction

    I read in a book "Optoelectronic Integration: Physics, Technology and Applications" edited by Osamu Wada. Ballistic Conduction and Superconductivity are both electron transport that are not affected by the collisions and scatterings. Ballistic conduction or Ballistic transport occurs when the...
  19. kelvin490

    Meissner effect and levitation

    In a field less than critical field, decreasing the temperature below the critical temperature will eliminate the magnetic field inside a superconductor and increase the magnetic field around it. (Meissner effect). But does it related to levitation effect of magnet on a superconductor? What...
  20. J

    Meissner effect and conservation of momentum in magnetic levitation

    I was recently reading about the Meissner effect, in which certain superconductors are able to "exclude" any external magnetic field lines from their interior, as seen in the right half of this diagram: I understand that some superconductors exhibit a sort of imperfect Meissner effect in...
  21. G

    Meissner effect oscillator

    I came up with the following idea of a device: We have a short circuited type-2 (to allow more current) superconducting solenoid. A current is flowing through the solenoid, and it creates magnetic induction inside, B1. Inside the solenoid we place a piece of type-1 superconductor. B1<critical...
  22. C

    Superconductors and the Meissner Effect

    So I'm a little confused about the Meissner Effect. If we have both a perfect conductor and a superconductor (both above Tc) and place them in a magnetic field and lower their temperatures so they exhibit their respective properties, the magnetic field inside the perfect conductor persists...
  23. F

    The Meissner effect within a galaxy

    Is it possible that a black hole is so tightly compacted, that its individual particles are unable to move? If this is the case then wouldn't it be extremely cold; close to, or even at absolute zero? Any significant heat would be on the surface caused by friction of attracted matter. With such a...
  24. W

    Meissner Effect in a strong field?

    While studying the M. Effect, a lot of sources state: "If a superconductor is applied in a weak field", I assume the effect would work even in a strong field? Weak or strong I think the Meissner Effect will always be applied as long as the superconductor is below critical temp. Or am I...
  25. A

    Uncovering the Meissner Effect: Clarifications Needed

    I need clarifications on Meissner effect. 1. According to this theory, when any diamagnetic substance is cooled below its critical temperature, it becomes a superconductor and it expels magnetic flux from inside. Is it applicable only to a diamagnetic substance or ferromagnetic substances...
  26. P

    Understanding the Meissner Effect: Causes and Explanation

    I am trying to understand WHY the Meissner effect occurs NOT WHAT the Meissner effect is. Does it occur because below Tc eddy currents are created in the surface of the material and these oppose and cancel any internal B field. Then above Tc these do not occur and it behaves like a normal...
  27. C

    What is The real cause of meissner effect in superconductors?

    As i have learnt, the lenz's law is not the cause of the meissner effect.This can also be proved by some experiments.I was wondering what may be the real cause for the meissner effect? As i don't know the cause, i have no idea, in which part of physics i must post this query.
  28. L

    How do surface currents differ between a superconductor and normal conductor?

    What happens to the electric field of a superconductor that is different to a normal conductor when electricity is going through it anything? Why do surface currents occur on a superconductor are they normally there on a normal conductor?
  29. S

    Meissner effect and conventional zero resistivity

    why shouldn't the meissner effect occur in a non conventional zero material?
  30. X

    The Meissner Effect & Lenz's Law

    Hi, I am quite confused about how the Meissner Effect works. I know that below the critical temperature of a superconductor, it will exclude all magnetic fields going through it. But why is this so? And I also know that as a magnet is brought near the surface of a cooled superconductor...
  31. R

    Exploring Practical Applications of the Meissner Effect

    Homework Statement Does anyone know what applications has Meissner effect? I have search on the internet but I did not find much only that the effect is not really of great practical use because it only occurs with superconductors, most effectively with type 1 supercondustors which have to...
  32. C

    Meissner Effect: Levitating a Magnet & Lenz's Law

    When we see people levitate a magnet over a superconductor, Does the magnet cause electrons to flow in the superconductor and this creates a B field to hold up the magnet. Is this similar to lenz's law. And why does the stationary magnet cause electrons to flow, I thought we needed a change in...
  33. R

    Is the Meissner effect responsible for a magnet floating above a superconductor?

    Hi all .. If a permanent magnet is placed on a superconducting material before cooling to the critical temperature, will this cause the magnet to float after cooling ? if yes, where would the energy come from ? thanks
  34. I

    Meissner effect, thought experiment.

    This has been on my mind for a while now; and I really need some outside input to either expand or put this idea to rest. So this idea relies on the Meissner effect; which during the transition of a material from a natural state to a superconducting state the magnetic permeability of that...
  35. J

    Meissner effect and Lenz's Law

    Hi, really quick question. Is there a relationship between the Meissner effect (in superconductors) and Lenz's law. Also, can the Meissner effect alone explain why a magnet can levitate over a superconductor, or do I need to learn about flux trapping (which isn't required by my syllabus).
  36. L

    The Meissner Effect: What Causes Magnet Repellency?

    My question is why does the material having no electrical resistance cause it to repell a magnet? And how can it repell and attract at the same time? I don't understand how the "flux trapping effect" works. I watched this video and it got me really interested in it. Thanks.
  37. S

    Meissner Effect- magnetic focusing

    Could superconductors be used to focus a magnetic field? For instance, let's say we have a superconducting cylinder and we place a wire coil in one end. If we put current through the wire, could it be used as a more effective Gauss gun than the same coil without the superconducting cylinder?
  38. D

    Exploring the Meissner Effect: How Superconductors Defy Gravity

    Check this out: http://www.youtube.com/watch?v=c3asSdngzLs" Why is this so stable? Is i due to the Meissner effect ? I mean you can't do this with two normal magnets. (normal: Tc = 300K+) I was thinking something like since the semiconductor, or what ever it is, becomes a superconducter...
  39. W

    How Does the Meissner Effect Cause a Superconductor to Levitate?

    I have been considering a situation, where a piece of superconducting (SC) material is put onto a magnet and then cooled through SC transition. As I understand, repulsion occurs and the SC piece gets away from the magnet (is it correct?). Assuming this happens, the SC piece may shoot upwards...
  40. N

    Meissner effect and superconductor

    Hi From what I understand the Meissner effect occurs when a current is induced in a superconductor, from a magnet, giving rise to a magnetic field from the superconductor that opposes the magnet. What stops the magnet from being completely repelled away from the superconductor when it is...
  41. W

    Superconductor 'meissner effect' help

    Hi, does anyone know how superconductors will oppose a magnetic flux even if it is unchanging. Thanks
  42. N

    Meissner Effect: Levitating a Magnet Before Cooling

    I've just successfully built and tested a superconductor. I've seen the meissner effect in action but there is one thing I'm wondering. If the superconductor is cooled below its critical temperature, and the magnet is then put on top it floats, as it should. It also levitates if the magnet is...
  43. D

    The Meissner Effect: Exploring the Physics of Superconductivity

    I had to flip a coin between thermo and quantum for this one, so forgive me if the coin made the wrong decision. :) I've been thinking about the Meissner Effect. (Well, a girl's got to think about something, anyway.) Suppose you take a piece of lead and shape it into a paraboloid. Chill...