Also a handwavy explanation aimed at people who aren't familiar with a lot of the concepts of condensed matter physics. Please salt with the knowledge that current theory can't fully explain how high temperature superconductors work. And that I'm not an expert in the field.
First concept, virtual particles vs real particles. When we talk about "an electron flowing through metal" it is not actually a single electron. As it moves, the electron will move into an atom, another gets knocked out. But in aggregate it "acts like" a single particle with possibly different properties from a real electron. For example it likely has a different mass. A virtual photon will travel slower than a real one. And so on.
Virtual particles can even correspond to things that aren't particles at all! For example sound is a wave, and quantum mechanically is carried by virtual particles known as phonons. These act exactly like any other particle, even though they are actually aggregate behavior of lots of other things!
A Cooper pair is a pair of things (eg electrons) that are interacting enough that they have a lower energy together than they would apart. Electrons are fermions, with half spin. They have a variety of properties, such as the Fermi exclusion principle. A bound pair of electrons becomes a virtual particle with an integer spin. Which makes it a boson, which behaves differently.
Superconductivity happens when charge is carried by bosons.
In high temperature superconductors, it looks like the electrons are at least partially bound by interaction with phonons. The high pressures change the speed of sound, and therefore change how easily Cooper pairs form.
Everything that I said above was based on what was known a couple of years ago.
However https://phys.org/news/2019-04-mechanism-high-temperature-sup... claims that there is now a theoretical explanation for high temperature superconductors, and the best guess above doesn't seem to be the real explanation. The real explanation being that the feature/TIQ-7651_unique_schema_version
Remember what I said about particles having a different mass moving through materials? The binding together of electrons through interaction with phonons seems to depend on the mass of the electrons. When you squeeze the lattice, that mass decreases.
>In high temperature superconductors, it looks like the electrons are at least partially bound by interaction with phonons. The high pressures change the speed of sound, and therefore change how easily Cooper pairs form.
Interesting. Do we know if it possible to disrupt superconductivity with sound at just the right frequency? And the converse, has anyone tried to enhance superconductivity by using sound (i.e. increase either the critical temperature, increase the current density, etc)?
HTS will stop superconducting once a certain amount of energy is added. This energy can be in the form of heat, magnetic field, electric current, or mechanical strain. If you keep the HTS colder you can accommodate more of the other forms of energy. I do not know if sound would disrupt superconductivity but since sound is a form of energy it is very likely.
First concept, virtual particles vs real particles. When we talk about "an electron flowing through metal" it is not actually a single electron. As it moves, the electron will move into an atom, another gets knocked out. But in aggregate it "acts like" a single particle with possibly different properties from a real electron. For example it likely has a different mass. A virtual photon will travel slower than a real one. And so on.
Virtual particles can even correspond to things that aren't particles at all! For example sound is a wave, and quantum mechanically is carried by virtual particles known as phonons. These act exactly like any other particle, even though they are actually aggregate behavior of lots of other things!
A Cooper pair is a pair of things (eg electrons) that are interacting enough that they have a lower energy together than they would apart. Electrons are fermions, with half spin. They have a variety of properties, such as the Fermi exclusion principle. A bound pair of electrons becomes a virtual particle with an integer spin. Which makes it a boson, which behaves differently.
Superconductivity happens when charge is carried by bosons.
In high temperature superconductors, it looks like the electrons are at least partially bound by interaction with phonons. The high pressures change the speed of sound, and therefore change how easily Cooper pairs form.