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Klitzing (Klitzing), Klaus von

( German physicist, Nobel Prize in Physics, 1985)

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Biography Klitzing (Klitzing), Klaus von
genus. June 28, 1943
Olaf German physicist Klaus von Klitzing was born during the Second World War in Sroda, in the then part of Germany (near germansko-Polish border). He was the third of four children forester Bogislava von Klitzing, and Annie nee Ulbrich. Shortly after the birth to. it became clear that the military situation in Germany deteriorated, and part of the Soviet Army will soon reach the vicinity Posen (now Poznan), and the family fled to the West Klitzing. Shortly before the end of the war, in April 1945, they settled in Lyuttene. In 1948, Mr.. family moved to Oldenburg, and then in 1951. - In Essen. K. received his secondary education in the Artland-Gymnasium city Kvahenbryuna that allowed him to specialize in theoretical physics from the Technical University of Braunschweig, where he joined in 1962
In Braunschweig K. first became acquainted with the problems of semiconductor physics. Talbot developed the interest in and to the X-ray spectroscopy, and even traveled to Darmstadt, to undergo a course of programming for computers, referring to the use of computer methods in spectroscopy. But his attention was drawn to the method of measuring the luminescence. He used them to determine the lifetime of carriers in the semiconductor indium antimonide and the results obtained in the thesis, written under the guidance of F.R. Kessler in 1969. Then K. moved to the University of Wurzburg, where for some time taught the technique of the laboratory experiment medical students. Next ten years he was engaged in semiconductor research. Almost all 1975. K. held in Oxford, where at that time produced the best superconducting magnets. For K. They were of particular interest, because a strong magnetic field are an important tool for investigating the behavior of electrons in semiconductors.
In search of more powerful magnetic fields to. in 1979. leaving Wц+rzburg and goes to work in the laboratory of strong magnetic fields in Grenoble. In 1980. he receives a new appointment and becomes a professor at the Technical University in Munich. In this position he remained until 1985, when he claimed the Director of the Institute of Solid State Physics in Stuttgart, Max-Planck. The combination of low temperatures and strong magnetic fields, which he was able to study in Grenoble, has played an important role in his discoveries related to the Hall effect. This phenomenon, first observed in 1880. American physicist Edwin X. Hall, previously seen only as a very imperfect means of measuring the concentration of electrons in semiconductors. In measurements on the basis of this effect, an electric current is passed through a sample placed in a magnetic field which is applied in the perpendicular direction. In the sample there is tension in the direction perpendicular and the current and magnetic field. The magnitude of this Hall voltage is usually proportional to the magnetic field and inversely proportional to the concentration of electrons. However, the conclusions that can be done on the basis of these measurements, have, as a rule, an error of about 10%, tk. There are many different kinds of interactions between electrons and the crystal lattice of the semiconductor machines.
. In Grenoble, working in collaboration with Michael Pepper from the Cavendish Laboratory at Cambridge University and Gerhard Dordoi from research laboratories, corporations 'Siemens' in Munich, TO
. conducted experiments differ from traditional measurements mainly nature of the sample. Silicon, which To. selected for the experiment, was part of the transistor, in which the mobile electrons can move only in a very thin layer near one of the surfaces of the device. Therefore, electrons can only move in two dimensions rather than three as in the homogeneous sample. The behavior of such 'two-dimensional' electrons under the influence of the applied voltage was significantly different from the behavior of electrons in the bulk sample.
The most striking feature of the experiment to. was the Hall voltage deviation from the usually smooth behavior when changing the applied magnetic field and electron concentration. When smooth increase in the number of electrons in the two-layer Hall voltage first continuously falls down, then some time remained constant, then again dropped to the next horizontal step, etc.. Dividing the value of the Hall voltage corresponding to each such step, the amount of current passing through the sample, we obtain a value of electrical resistance. By comparing a series received by the resistance, R. noticed that they are expressed by simple fractions share the same values: the resistance in ohms 25.183. This resistance can be represented as a ratio of two fundamental constants of nature - the Planck constant, which manages all the quantum-mechanical phenomena, and the square of the electric charge of an electron.
. An important feature of the result was the high precision with which to implement this ratio
. Repeated experiments not only on samples of various shapes, but also on transistors made of different materials, the value of relationships has always been measured with an accuracy of about one ten millionth. This stability has allowed measurements to. immediately conjectured that the phenomenon now known under the name of the quantum Hall effect, could be the basis of an entirely new standard of electrical resistance. On its opening for. and his colleagues reported in August 1980. in the journal 'Fizikal Review leters' ( "Physical Review Letters").
Study, published K. in 1980, is notable for at least three respects. First, it showed that the effects of quantum theory, is most often seen in the behavior of microscopic quantities, such as individual electrons can be observed in measurements of electrical current in a laboratory scale. Secondly, the observed effect was a complete surprise for theoretical physicists for decades engaged in the study of semiconductors. Third, the quantum Hall effect was allowed to obtain the results, reproduced with such precision that they once led to the idea of a new international standard unit of electrical resistance - Ohm.
. For the discovery of the quantum Hall effect to
. was awarded the Nobel Prize in Physics 1985. In view of the Royal Swedish Academy noted that the work to. 'opened up a new area of research is vital not only for theory but for applications ... We are dealing here with a new phenomenon in quantum physics, with the phenomenon, the characteristics of which are understood only partially. "
. Accuracy and reproducibility, which can be measured by the quantum Hall effect, make it a phenomenon whose significance goes far beyond the metrology and physics of semiconductor devices
. As measured by the unit of resistance depends only on the most fundamental constants of nature, the resulting K. result is important for many other areas of physics. For example, the fine structure emission spectra of hot gases is determined by the same combination of fundamental constants, and that the quantum Hall effect. Thus, the measured Hall resistance has become cumbersome test of the correctness of theoretical calculations, the predicted values of the fine structure constant of atomic spectroscopy.
In some respects, the opening of the quantum Hall effect to. can compare with the phenomenon of superconducting tunneling predicted two decades earlier by Brian D. Josephson. Both effects make it possible to observe in a laboratory experiment, the quantum mechanical behavior, usually a limited system of atomic dimensions. Both effects led to the establishment of new absolute standards of electrical quantities - in the Josephson volt and ohm in the case of the quantum Hall effect. By Portfolio. are of particular importance, because they stimulated the study of electrons, effectively limited two-dimensional space. Many new phenomena discovered in subsequent years, and new problems arising in the physics of electronic layers, largely due to its remarkable appearance of the observations made to. in 1980
In 1971, Mr.. K. married Renate Falkenberg, and they had two sons and a daughter. In addition to the Nobel Prize he was awarded Walter-Schottky Germanskogo Physical Society (1981) and Hewlett Packard Prize of the European Physical Society (1982).


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