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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.
Penguin diagram: a quark changes flavor via a W or Z loop Tadpole diagram: One loop diagram with one external leg Self-interaction or oyster diagram An electron emits and reabsorbs a photon Box diagram The box diagram for kaon oscillations: Photon-photon scattering: Higgs boson production: Via gluons and top quarks: Via quarks and W or Z bosons ...
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 ...
Conversely, the (gapless) electron order present in the normal metal is also carried over to the superconductor in that the superconducting gap is lowered near the interface. The microscopic model describing this behavior in terms of single electron processes is called Andreev reflection. It describes how electrons in one material take on the ...
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.
The experiment demonstrated for the first time that superconductors were more than just perfect conductors and provided a uniquely defining property of the superconductor state. The ability for the expulsion effect is determined by the nature of equilibrium formed by the neutralization within the unit cell of a superconductor.
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 ...
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 ...