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Superconductor workings

by Salvador
Tags: superconductor, workings
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Salvador
#1
Apr18-14, 04:47 PM
P: 44
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 carrying parts.
In ordinary conductor the electrons have higher kinetic energy at room temperature and when current flows they hit the ion lattice and so impart some of their energy to the lattice which results as heat.
in superconductor the electrons have much lower kinetic energy so electrons form pairs and the whole current in the length of the conductor is more like a solid stream , the electron current becomes a little ion lattice like?
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Drakkith
#2
Apr18-14, 07:14 PM
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Not really. For normal metals which become superconductive at very low temperatures, the key lies in the fact that when the momentum of the electrons is low enough, they can bind together in pairs. Since it takes energy to break this bond, there is a minimum amount of work that must be done on them by any disturbance to break them apart, which forbids small disturbances like scattering from stealing energy from them.

A more accurate description involves energy states. Per wiki: http://en.wikipedia.org/wiki/Cooper_pair

Cooper originally considered only the case of an isolated pair's formation in a metal. When one considers the more realistic state of many electronic pair formations, as is elucidated in the full BCS Theory, one finds that the pairing opens a gap in the continuous spectrum of allowed energy states of the electrons, meaning that all excitations of the system must possess some minimum amount of energy. This gap to excitations leads to superconductivity, since small excitations such as scattering of electrons are forbidden.[6] The gap appears due to many-body effects between electrons feeling the attraction.
Salvador
#3
Apr19-14, 02:54 PM
P: 44
so it means that the only basic variable for superconductivity in metals is temperature which is a measure of the kinetic energy of the electrons?

is there any other know or theorized way in which the electrons could have low enough kinetic energy for Cooper pairs to form?


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