Superdiamagnetism (or perfect diamagnetism) is a phenomenon occurring in certain materials at low temperatures, characterised by the complete absence of magnetic susceptibility and the exclusion of the interior magnetic field. Superdiamagnetism is a feature of superconductivity. It was identified in 1933, by Walter Meissner and Robert Ochsenfeld (the Meissner effect). A phenomenon (plural: phenomena) is an observable event, especially something special (literally something that can be seen from the Greek word phainomenon = observable). ... Cryogenics is the study of very low temperatures or the production of the same, and is often confused with cryobiology, the study of the effect of low temperatures on organisms, or the study of cryopreservation. ... In electrical engineering, the magnetic susceptibility is the degree of magnetization of a material in response to an applied magnetic field. ... A high-temperature superconductor levitating above a magnet (with boiling liquid nitrogen underneath) demonstrates the Meissner effect. ... 1933 (MCMXXXIII) was a common year starting on Sunday (link will take you to calendar). ... Walter Meißner was born in Berlin in 1882, where he studied machine construction and physics, promoting with Max Planck. ... Robert Ochsenfeld was a German physicist born on 18 May 1901 in Helberhausen. ... Meissner effect Diagram of the Meissner effect. ...

Superdiamagnetism established that the superconductivity was a stage of phase transition. Superconducting magnetic levitation is due to the Superdiamagnetism (which repels a permanent magnet) and flux pinning, which stops the magnet from sliding away. In physics, a phase transition, (or phase change) is the transformation of a thermodynamic system from one phase to another. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Flux pinning is the phenomenon where a magnets lines of force (called flux) become trapped or pinned inside a superconducting material. ...

Superdiamagnetism : Magnetic field lines, represented as arrows, are excluded from a superconductor when it is below its critical temperature.

Diagram of the meissner effect, showing mag field lines, Made by Jaguar2k in paint (yes i know). ...

Theory

Fritz London and Hien London developed the theory that the exclusion of magnetic flux is brought about by electrical "screening currents" that flow at the surface of the superconducting metal and which generate a magnetic field that exactly cancels the externally applied field inside the superconductor. These screening currents are generated whenever a superconducting metal is brought inside a magnetic field. This may be understood from the fact that a superconductor has zero electrical resistance (so the "eddy currents" induced by motion of the metal inside a magnetic field will not decay). Fritz, at the Royal Society in 1935, stated that the thermodynamic state would be described by a single wave function. Fritz Wolfgang London (March 7, 1900–March 30, 1954) was a Jewish German-American physicist for whom the London force is named. ... Magnetic flux, is a measure of quantity of magnetism, taking account of the strength and the extent of a magnetic field. ... Hot metal work from a blacksmith Look up Metal in Wiktionary, the free dictionary. ... Current flowing through a wire produces a magnetic field (B, labeled M here) around the wire. ... 1935 (MCMXXXV) was a common year starting on Tuesday (link will take you to calendar). ...

Screening currents also appear in a situation where an initially normal conducting metal is placed inside a magnetic field, as soon as the metal is cooled below the transition temperature (such that it becomes superconducting). This expulsion of magnetic field on cooling down the metal cannot be explained any more by merely assuming zero resistance and is called the Meissner effect. It shows that the superconducting state does not depend on the history of preparation (only on the present values of temperature, pressure and magnetic field), and therefore is a true thermodynamic state. Meissner effect Diagram of the Meissner effect. ...

See also

• Diamagnetism
• Superfluidity
• Superconductivity
• Timeline of low-temperature technology

Brugmans (in 1778) was the first person to observe that certain materials were repelled by magnetic fields. ... Superfluidity is a phase of matter characterised by the complete absence of viscosity. ... A high-temperature superconductor levitating above a magnet (with boiling liquid nitrogen underneath) demonstrates the Meissner effect. ... Timeline of low-temperature technology c. ...

In physics, magnetism is one of the phenomena by which materials exert an attractive or repulsive force on other materials. ... Brugmans (in 1778) was the first person to observe that certain materials were repelled by magnetic fields. ... Paramagnetism is the tendency of the atomic magnetic dipoles to align with an external magnetic field. ... Superparamagnetism is a phenomenon by which magnetic materials may exhibit a behavior similar to paramagnetism at temperatures below the Curie or the Neel temperature. ... Ferromagnetism is a phenomenon by which a material can exhibit a spontaneous magnetization, and is one of the strongest forms of magnetism. ... In materials that exhibit antiferromagnetism, the spins of magnetic electrons align in a regular pattern with neighboring spins pointing in opposite directions. ... In physics, a ferrimagnetic material is one in which the magnetic moment of the atoms on different sublattices oppose as in antiferromagnetism but the opposing moments are unequal and a spontaneous magnetization remains. ... Metamagnetism is a physical state of matter characterized by a superlinear increase of magnetization over a narrow range of applied magnetic field. ... A spin glass is a disordered material exhibiting high magnetic frustration. ...

References

• Shachtman, Tom, "Absolute Zero: And the Conquest of Cold". Houghton Mifflin Company, December 1999. ISBN 0395938880