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Andreev reflection, named after the Russian physicist Alexander F. Andreev, is a type of particle scattering which occurs at interfaces between a superconductor (S) and a normal state material (N). It is a charge-transfer process by which normal current in N is converted to supercurrent in S.
Diagram of Andreev reflection. An electron meeting the interface between a normal conductor and a superconductor produces a Cooper pair in the superconductor and a retroreflected electron hole in the normal conductor. Legend: "N" = normal conductor, "S" = superconductor, red = electron, green = hole. Arrows indicate the spin band occupied by ...
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Phase diagram (B, T) of a type I superconductor : if B < B c, the medium is superconducting. T c is the critical temperature of a superconductor when there is no magnetic field. The interior of a bulk superconductor cannot be penetrated by a weak magnetic field, a phenomenon known as the Meissner effect. When the applied magnetic field becomes ...
These materials are type-II superconductors with substantial upper critical field H c2, and in contrast to, for example, the cuprate superconductors with even higher H c2, they can be easily machined into wires. Recently, however, 2nd generation superconducting tapes are allowing replacement of cheaper niobium-based wires with much more ...
Diagram of the Meissner effect. Magnetic field lines, represented as arrows, are excluded from a superconductor when it is below its critical temperature. In condensed-matter physics , the Meissner effect (or Meißner–Ochsenfeld effect ) is the expulsion of a magnetic field from a superconductor during its transition to the superconducting ...
Alexander Fyodorovich Andreev (Russian: Александр Фёдорович Андреев, 10 December 1939 – 14 March 2023) [1] was a Russian theoretical physicist best known for explaining the eponymous Andreev reflection. [2] Andreev was educated at the Moscow Institute of Physics and Technology, starting in 1959 and graduating ahead of ...
The size of the critical current (which can be as large as 100 amperes in a 1-mm wire) depends on the nature and geometry of the specimen and is related to whether the magnetic field produced by the current exceeds the critical field at the surface of the superconductor.