What are Cooper pairs in BCS theory?

In condensed matter physics, a Cooper pair or BCS pair (Bardeen–Cooper–Schrieffer pair) is a pair of electrons (or other fermions) bound together at low temperatures in a certain manner first described in 1956 by American physicist Leon Cooper.

How do Cooper pairs explain superconductivity?

The classical (or BCS) theory of superconductivity states that, below a specific critical temperature, the fermionic electrons in a metal pair up to create bosons called Cooper pairs. These bosons form a phase-coherent condensate that can flow through a material without scattering – the result being superconductivity.

What is superconductor PPT?

Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature. This power-point presentation include. 1. Introduction to Superconductors. 2.

How is Cooper pair formed?

Cooper Pair Formation These pairs are known as Cooper pairs and are formed by electron-phonon interactions – an electron in the cation lattice will distort the lattice around it, creating an area of greater positive charge density around itself.

How do Cooper pairs work?

Cooper pairs are a pair of electrons with opposite spins that are loosely bound at absolute temperatures due to electron-lattice interactions. Their condensation to bosonic states at low temperatures is believed to be the reason behind superconductivity.

How do Cooper pairs move?

Physically, the Cooper pair is more resistant to vibrations within the lattice as the attraction to its partner will keep it ‘on course’ – therefore, Cooper pairs move through the lattice relatively unaffected by thermal vibrations (electron-phonon interactions) below the critical temperature.

What are Type 1 and Type 2 superconductors?

Type-I superconductors are generally pure metals. Type-II superconductors are generally alloys and complex oxides of ceramics. BCS theory can be used to explain the superconductivity of type-I superconductors. BCS theory cannot be used to explain the superconductivity of type-II superconductors.

What is Meissner effect PDF?

1. The Meissner Effect. When a material makes the transition from the normal to superconducting state, it actively excludes magnetic fields from its interior; this is called the Meissner effect.