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Superconductor Insulator Transition
The Superconductor Insulator Transition is an example of a quantum phase transition, whereupon tuning some parameter in the Hamiltonian, a dramatic change in the behavior of the electrons occurs. The nature of how this transition occurs is disputed, and many studies seek to understand how the order parameter, \Psi =\Delta \exp(i\theta), changes. Here \Delta is the amplitude of the order parameter, and \theta is the phase. Most theories involve either the destruction of the amplitude of the order parameter - by a reduction in the density of states at the Fermi surface, or by destruction of the phase coherence; which results from the proliferation of vortices. Destruction of superconductivity In two dimensions, the subject of superconductivity becomes very interesting because the existence of true long-range order is not possible. How then is superconductivity obtained? In the 70's, Kosterlitz and Thouless (along with Berezinski) showed that a different kind of long-range orde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Phase Transition
In physics, a quantum phase transition (QPT) is a phase transition between different quantum phases (phases of matter at zero temperature). Contrary to classical phase transitions, quantum phase transitions can only be accessed by varying a physical parameter—such as magnetic field or pressure—at absolute zero temperature. The transition describes an abrupt change in the ground state of a many-body system due to its quantum fluctuations. Such a quantum phase transition can be a second-order phase transition. Quantum phase transitions can also be represented by the topological fermion condensation quantum phase transition, see e.g. strongly correlated quantum spin liquid. In case of three dimensional Fermi liquid, this transition transforms the Fermi surface into a Fermi volume. Such a transition can be a first-order phase transition, for it transforms two dimensional structure (Fermi surface) into three dimensional. As a result, the topological charge of Fermi liquid changes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hamiltonian (quantum Mechanics)
Hamiltonian may refer to: * Hamiltonian mechanics, a function that represents the total energy of a system * Hamiltonian (quantum mechanics), an operator corresponding to the total energy of that system ** Dyall Hamiltonian, a modified Hamiltonian with two-electron nature ** Molecular Hamiltonian, the Hamiltonian operator representing the energy of the electrons and nuclei in a molecule * Hamiltonian (control theory), a function used to solve a problem of optimal control for a dynamical system * Hamiltonian path, a path in a graph that visits each vertex exactly once * Hamiltonian group, a non-abelian group the subgroups of which are all normal * Hamiltonian economic program, the economic policies advocated by Alexander Hamilton, the first United States Secretary of the Treasury See also * Alexander Hamilton (1755 or 1757–1804), American statesman and one of the Founding Fathers of the US * Hamilton (other) Hamilton may refer to: People * Hamilton (name), a common ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fermi Surface
In condensed matter physics, the Fermi surface is the surface in reciprocal space which separates occupied from unoccupied electron states at zero temperature. The shape of the Fermi surface is derived from the periodicity and symmetry of the crystalline lattice and from the occupation of electronic energy bands. The existence of a Fermi surface is a direct consequence of the Pauli exclusion principle, which allows a maximum of one electron per quantum state. The study of the Fermi surfaces of materials is called fermiology. Theory Consider a spin-less ideal Fermi gas of N particles. According to Fermi–Dirac statistics, the mean occupation number of a state with energy \epsilon_i is given by :\langle n_i\rangle =\frac, where, *\left\langle n_i\right\rangle is the mean occupation number of the i^ state *\epsilon_i is the kinetic energy of the i^ state *\mu is the chemical potential (at zero temperature, this is the maximum kinetic energy the particle can have, i.e. Fermi ene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mermin–Wagner Theorem
In quantum field theory and statistical mechanics, the Mermin–Wagner theorem (also known as Mermin–Wagner–Hohenberg theorem, Mermin–Wagner–Berezinskii theorem, or Coleman theorem) states that continuous symmetries cannot be spontaneously broken at finite temperature in systems with sufficiently short-range interactions in dimensions . Intuitively, this means that long-range fluctuations can be created with little energy cost and since they increase the entropy they are favored. This is because if such a spontaneous symmetry breaking occurred, then the corresponding Goldstone bosons, being massless, would have an infrared divergent correlation function. The absence of spontaneous symmetry breaking in dimensional systems was rigorously proved by David Mermin, Herbert Wagner (1966), and Pierre Hohenberg (1967) in statistical mechanics and by in quantum field theory. That the theorem does not apply to discrete symmetries can be seen in the two-dimensional Ising model. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
David J
David John Haskins (born 24 April 1957, Northampton, Northamptonshire, England), better known as David J, is a British alternative rock musician, producer, and writer. He is the bassist for the gothic rock band Bauhaus and for Love and Rockets. He has composed the scores for a number of plays and films, and also wrote and directed his own plays, ''Silver for Gold (The Odyssey of Edie Sedgwick)'', in 2008, which was restaged at REDCAT in Los Angeles in 2011, and ''The Chanteuse and The Devil's Muse'' in 2011. His artwork has been shown in galleries internationally, and he has been a resident DJ at venues such as the Knitting Factory. David J has released a number of singles and solo albums, and in 1990 he released one of the first No. 1 hits on the then nascent Modern Rock Tracks charts, with "I'll Be Your Chauffeur". His most recent single, "The Day That David Bowie Died" entered the UK vinyl singles chart at number 4 in 2016. The track appears on his double album, ''Vaga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vadim Berezinskii
Vadim L'vovich Berezinskii (July 15, 1935 in Kyiv – June 23, 1980 in Moscow) was a Soviet physicist. He was born in Kyiv, graduated from Moscow State University in 1959, and worked in Moscow and the Landau Institute for Theoretical Physics. He is famous for having identified the role played by topological defects in the low-temperature phase of two-dimensional systems with a continuous symmetry. His work led to the discovery of the Berezinskii–Kosterlitz–Thouless transition, for which John M. Kosterlitz John Michael Kosterlitz (born June 22, 1943) is a British-American physicist. He is a professor of physics at Brown University and the son of biochemist Hans Kosterlitz. He was awarded the 2016 Nobel Prize in physics along with David Thouless ... and David J. Thouless were awarded the Nobel Prize in 2016. He also developed a technique for treating electrons in one-dimensional disordered systems and provided first consistent proof of one-dimensional localization, and pred ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Law
In statistics, a power law is a Function (mathematics), functional relationship between two quantities, where a Relative change and difference, relative change in one quantity results in a proportional relative change in the other quantity, independent of the initial size of those quantities: one quantity varies as a Exponentiation, power of another. For instance, considering the area of a square in terms of the length of its side, if the length is doubled, the area is multiplied by a factor of four. Empirical examples The distributions of a wide variety of physical, biological, and man-made phenomena approximately follow a power law over a wide range of magnitudes: these include the sizes of craters on the moon and of solar flares, the foraging pattern of various species, the sizes of activity patterns of neuronal populations, the frequencies of words in most languages, frequencies of family names, the species richness in clades of organisms, the sizes of power outages, volcanic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anatoly Larkin
Anatoly Ivanovich Larkin (russian: Анатолий Иванович Ларкин; October 14, 1932 – August 4, 2005) was a Russian theoretical physicist, universally recognised as a leader in theory of condensed matter, and who was also a celebrated teacher of several generations of theorists. Born in a small town of Kolomna in Moscow region, Larkin went on to receive his education at the Moscow Engineering Physics Institute. He worked on his PhD on the properties of plasmas under the supervision of A.B.Migdal and later received the degree of Doctor of Science (1965) for studies of superconductivity. Research at the I.V. Kurchatov Institute in Moscow (1957–66) was followed by nearly 40 years of work at the L.D.Landau Institute for Theoretical Physics in Chernogolovka, Moscow region, where he moved in 1966. During 1970–1991, he was also a professor at Moscow State University. Since 1995, Larkin was a professor of physics at the University of Minnesota and a member of W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal–insulator Transition
Metal–insulator transitions are transitions of a material from a metal (material with good electrical conductivity of electric charges) to an insulator (material where conductivity of charges is quickly suppressed). These transitions can be achieved by tuning various ambient parameters such as temperature, pressure or, in case of a semiconductor, doping. History The basic distinction between metals and insulators was proposed by Bethe, Sommerfeld and Bloch in 1928/1929. It distinguished between conducting metals (with partially filled bands) and nonconducting insulators. However, in 1937 de Boer and Evert Verwey reported that many transition-metal oxides (such as NiO) with a partially filled d-band were poor conductors, often insulating. In the same year, the importance of the electron-electron correlation was stated by Peierls. Since then, these materials as well as others exhibiting a transition between a metal and an insulator have been extensively studied, e.g. by Si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anderson's Theorem (superconductivity)
In the field of superconductivity, Anderson's theorem states that superconductivity in a conventional superconductor is robust with respect to (non-magnetic) disorder in the host material. It is named after P. W. Anderson, who discussed this phenomenon in 1959, briefly after BCS theory was introduced. One consequence of Anderson's theorem is that the critical temperature Tc of a conventional superconductor barely depends on material purity, or more generally on defects. This concept breaks down in the case of very strong disorder, e.g. close to a superconductor-insulator transition. Also, it does not apply to unconventional superconductor Unconventional superconductors are materials that display superconductivity which does not conform to either the conventional BCS theory or Nikolay Bogolyubov's theory or its extensions. History The superconducting properties of CeCu2Si2, a ty ...s. In fact, strong suppression of Tc with increasing defect scattering, thus non-validity of Ande ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superconductivity
Superconductivity is a set of physical properties observed in certain materials where electrical resistance vanishes and magnetic flux fields are expelled from the material. Any material exhibiting these properties is a superconductor. Unlike an ordinary metallic conductor, whose resistance decreases gradually as its temperature is lowered even down to near absolute zero, a superconductor has a characteristic critical temperature below which the resistance drops abruptly to zero. An electric current through a loop of superconducting wire can persist indefinitely with no power source. The superconductivity phenomenon was discovered in 1911 by Dutch physicist Heike Kamerlingh Onnes. Like ferromagnetism and atomic spectral lines, superconductivity is a phenomenon which can only be explained by quantum mechanics. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor during its transitions into the sup ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
