Schrieffer (Schrieffer), J. Robert( The American physicist, Nobel Prize in Physics, 1972)
Comments for Schrieffer (Schrieffer), J. Robert
Biography Schrieffer (Schrieffer), J. Robert
genus. May 31, 1931
American physicist John Robert Schrieffer was born in g. Oak Park (Illinois), the son of John G. Schrieffer and Louise (nee Anderson) Schrieffer. In 1940. family moves to r. Manhasset (New York), and after nine years in Mr.. Yustis (Florida). After Yustisskoy high school in 1949. SH. entered the Massachusetts Institute of Technology, intending to become an electrical engineer. Two years later, he chooses a specialty and physics in 1953. received a bachelor's degree. In 1954, Mr.. it protects the University of Illinois dissertation, done under the guidance of a recognized authority in the field of solid state physics, John Bardeen, and receives a master's degree. Thesis III. was devoted to the study of electronic conductivity on the surface of the semiconductor. Upon completion of the dissertation, he joined Bardin study the phenomenon of superconductivity and the properties of matter at temperatures close to absolute zero (273 б¦ C).
In 1911, Mr.. Netherlands physicist Heike Kamerlingh Onnes discovered that some materials lose their resistance to electric current when cooled to temperatures only a few degrees above absolute zero. A new phenomenon called superconductivity, was seen as a big surprise, and it took almost 50 years before it was fully understood.
. Almost all metals when cooled become better conductors, . as the main source of electrical resistance is thermal vibrations of atoms in the metal, . scattered electron carriers of electric current cooling of the metal reduces the amplitude of oscillations and thus eliminates the obstacle the flow of electrons,
. In normal metals increased the electrical conductivity occurs gradually, . and the resistance drops to zero only at absolute zero (unachievable in practice) in the superconductor (and this is particularly surprising) all electrical resistance disappears suddenly at a certain temperature above absolute zero, the metal atoms still make the thermal fluctuations, . but current, . carrying electrons, . runs smoothly,
. Another unusual property of superconductors was discovered in 1933
. German physicist Walter Meissner. Meissner found, . that superconductors can have the perfect diamagnetism of the magnetic field is pushed out from inside the body of the superconducting, . and such a body is repelled by both poles of a magnet, . as a result of magnetic material, . placed over a superconductor, . hangs in a state of levitation,
. If a superconducting material is placed in a sufficiently strong magnetic field, then the material loses its superconductivity and becomes a normal conductor. In 1935. German physicist Fritz London suggested that superconductivity is the diamagnetic aspect of its main property. With speculations London came to the conclusion that the superconductivity is a quantum phenomenon that occurs on a macroscopic scale.
In 1950, Mr.. several American physicists studied the superconductivity in metals, . having several isotopes (isotopes commonly understood as a variety of chemical element with the same number of electrons and protons - and, . hence, . with the same chemical properties, . but with different numbers of neutrons),
. It turned out that the critical temperature at which the isotope becomes superconducting is inversely proportional to its atomic mass. Knowing, . that the atomic weight can affect the properties of the solid state only one way to change the characteristics of, . responsible for the distribution of fluctuations, . - Bardin suggested, . that superconductivity depends on the interaction of conduction electrons with vibrational motion of atoms in the metal,
. According to Bardin, the conduction electrons must communicate with each other through interaction with these oscillations.
In 1956, Mr.. one postdoctoral students in the University of Illinois Bardeen Leon H. Cooper proved that the interaction of conduction electrons with atomic vibrations leads to the formation of bound pairs of electrons. An electron moving through a crystal of metal, attracts the surrounding positively charged atoms. This slight deformation of the crystal lattice creates a momentary concentration of positive charge, which in turn attracts a second electron. Thus, two electrons are indirectly related through the mediation effect of the crystal lattice. About these electrons are said to form a Cooper pair.
W. Bardeen and tried to extend the idea of the impact of Cooper pairs of electrons on the behavior of the overwhelming majority of free electrons in the superconducting solid. SH. have wanted to abandon further attempts to find a solution, . but Bardin, . which is just at the time was to go to Sweden at a ceremony awarding him the Nobel Prize in Physics for 1956, . awarded to him for his contribution to the invention of the transistor, . persuaded W,
. reflect more a month over the issue, and this month's W. really managed to develop a statistical method, which provided a solution.
. Upon his return, three researchers Bardin Bardin, . Cooper and S., . combined efforts, . showed, . that the interaction between Cooper pairs covers many free electrons in the superconducting, . forcing them to move strictly in concert, . 'pace' As predicted by London, . superconducting electrons form a quantum state, . covering all material,
. Below the critical temperature strength of the pairing, . hold electrons in their coherent motion, . on the intensity exceeds the thermal vibrations of atoms in a metal Perturbation, . able to reject a single electron, and thus generating electrical resistance, . can not do, . without affecting all the electrons, . participating in the superconducting state,
. This event is extremely unlikely, and as a result of superconducting electrons drift coherently without energy loss. For contribution to the theory of superconductivity W. in 1957. was awarded a doctoral degree in the University of Illinois.
Bardeen - Cooper - Schrieffer (BCS) has been recognized as one of the most important achievements in theoretical physics since the inception of quantum theory. In 1958, using the BCS theory, Cooper and his colleagues predicted that the very cold liquid helium-3 (an isotope of helium, whose nucleus contains two protons and one neutron) must possess superfluidity, ie. move in an unusual state of matter characterized by the absence of viscosity and surface tension. Previously, superfluidity was observed in more conventional isotope helium-4 (whose nucleus contains two protons and two neutrons), but it was felt that there was no way in the isotopes with an odd number of nuclear particles. Superfluidity of helium-3 has been confirmed experimentally in 1962
In 1972. C. Cooper and Bardin was awarded the Nobel Prize in Physics "for their jointly created the theory of superconductivity, usually called the BCS theory '. Speaking at the presentation of the winners, Stig Lundquist, a member of the Royal Swedish Academy of Sciences, said: 'In his seminal book, you offered a full explanation of the phenomenon of superconductivity. Your theory also allows us to predict new effects and stimulate theoretical and experimental studies. Subsequent work in the field of superconductivity dramatically confirmed the widest range of applicability and validity of the basic concepts and ideas contained in your fundamental paper in 1957 '.
. BCS theory has had a profound influence on the physical theory, and the technique
. That it led to the creation of superconductors that can operate at high temperatures or in the presence of strong magnetic fields. These superconductors are crucial for the establishment of electromagnets that generate powerful magnetic fields, but consume little power. Such magnets are used in the study of thermonuclear fusion, in magnetohydrodynamics (generating an electric current passing highly ionized gas through a magnetic field), with acceleration to high energies of particles in particle physics, a magnetic suspension during movement without friction in the biological and physical studies, . related to the interaction of atoms and electrons with a strong magnetic field, when you create a compact high-power generators,
. Opening physicist from Wales, Brian D. Josephson special regimes on the borders between two superconductors (Josephson effect) led to the creation of sensors, . capable of detecting magnetic activity inside living organisms and to detect deposits of iron ore and crude oil based on their magnetic properties.,
. In 1957 ... 1958
. on the Rights of the National Science Foundation Postdoctoral students W. investigated superconductivity in the University of Birmingham (England) and the Niels Bohr Institute in Copenhagen (Denmark). Also in I960 g. He met Anne Grete Thomsen. A few months later they were married. They have two daughters and a son.
W. taught physics at the University of Chicago (1957 ... 1960), University of Illinois (1959 ... 1960), University of Pennsylvania (1962). Cornell University (1969 ... 1975) and 1975. - University of California at Santa Barbara. He is also involved in the study of magnetic properties of materials, properties of alloys and surface effects. At the University of Pennsylvania W. became one of the sponsors of the report, which established the program of Afro-American Studies. It does not hurt himself, he has on every occasion there is a ready sarcastic remark.
W. won numerous awards including the Comstock Prize of the American National Academy of Sciences (1968), . Prize Oliver Bahla in solid state physics of the American Physical Society (1968) and John Ericsson medal of the American Society of Swedish Engineers (1976),
. He is an honorary doctor of five universities, a member of the U.S. National Academy of Sciences, the American Academy of Arts and Sciences, the American Philosophical Society and the Royal Danish Academy of Arts and Sciences.