B What exactly causes the Meissner effect

[TheCelt]

TL;DR Summary

What causes the effect when the critical temperature is reached?

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 happening at the atomic level to give rise to this effect?

 

[Michael Price]

Summary: What causes the effect when the critical temperature is reached?

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 happening at the atomic level to give rise to this effect?

Do you mean, passing through a superconducting object? There are multiple explanations, all correct.

1. surface currents, created by back EMF, create magnetic fields that exactly cancel the applied field. Just as happens in conductors, but more effectively.
2. Photons (which convey the E and B fields) acquire an effective mass inside the superconductor, which turns the EM interaction into a short range force. Hence only surface E & B fields.

https://en.m.wikipedia.org/wiki/Effective_mass_(solid-state_physics)https://en.m.wikipedia.org/wiki/Meissner_effect

 

[vanhees71]

To be more precise: Superconductivity is effectively described by the Higgs mechanism of QED in the medium. In this connection one should really talk about the "Anderson-Higgs mechanism", because Anderson had the idea for superconductivity at the same time or even before Higgs, Brout, Englert, Kibble, Guralnik, and Hagen found it as the solution for the quibble about massive weak gauge bosons, i.e., how to get a consistent gauge theory with massive gauge bosons.

https://doi.org/10.1143/PTPS.86.43

 

[Michael Price]

To be more precise: Superconductivity is effectively described by the Higgs mechanism of QED in the medium. In this connection one should really talk about the "Anderson-Higgs mechanism", because Anderson had the idea for superconductivity at the same time or even before Higgs, Brout, Englert, Kibble, Guralnik, and Hagen found it as the solution for the quibble about massive weak gauge bosons, i.e., how to get a consistent gauge theory with massive gauge bosons.

https://doi.org/10.1143/PTPS.86.43

Which is also described at the end of the wikipedia article, where the link between the London effect and the Higgs mechanism is made.