2023-06-28 07:59:54
Discovering a law of nature is probably the dream of every scientist. And if it is also named after the discoverer himself, the life’s work is complete. For Klaus von Klitzing, this dream suddenly came true on the night of February 5, 1980, when he was investigating the conduction behavior of electrons in thin semiconductor layers in extremely cold conditions in the high magnetic field laboratory in Grenoble.
He carefully measured, in small increments, how the electrical potential across the sample changed as a function of the strength of the applied magnetic field, and meticulously noted the results in his lab notebook. Just as he had learned as a student at the TU Braunschweig. To the surprise of the then 36-year-old physicist, who had habilitated two years previously in Würzburg and was one of the first young researchers to receive a Heisenberg fellowship, the tension did not increase linearly, as one would actually expect, but in leaps and bounds: a unmistakable sign that this is a quantum effect.
Regardless of the material and nature of the sample, the steps were always multiples of the same number. The physicist was amazed when he was able to precisely calculate its value from two well-known natural constants: Planck’s constant h and the square of the elementary charge e. The constant also had the unit ohm of electrical resistance. With the phenomenon of the quantum Hall effect discovered by Klitzing, a universal reference value for electrical resistances existed from then on.
A welcome guest in Lindau: Klaus von Klitzing at the get-together evening in the Lindau Inselhalle during the 60th Meeting of the Nobel Prize Winners in 2010. : Photo: Frank Röth
This could be measured anywhere and anytime on any semiconductor and thus reproduced much more precisely than was previously possible with standardized wire resistors. Since January 1, 1990, resistance calibrations have therefore been carried out on the basis of the internationally defined Von Klitzing constants (RK = 25,812.807 ohms).
Nobel laureate makes an impact
Klaus von Klitzing, who was born in Schroda in what is now Poland and grew up in Lower Saxony after the war, was awarded the Nobel Prize in 1985 for his discovery, which is also of great importance for microelectronics. The news was a sensation: Von Klitzing was the first German to win the Nobel Prize in Physics after 22 years, who also received the prize alone – which rarely happens.
Shortly before that, in January 1985, Klaus von Klitzing had been appointed director at the Max Planck Institute for Solid State Research in Stuttgart. There he researched, among other things, quantum effects in nanometer-sized electronic components and was a member of the board of directors of the institute after his retirement until 2018. Klitzing was very happy when he found out that his natural constant could also be used to redefine the kilogram with the help of SI units.
Manfred Lindinger Published/Updated: , Recommendations: 4 Stephan Klenner Published/Updated: , Recommendations: 27 Manfred Lindinger Published/Updated: Recommendations: 24
Right from the start, he used his fame as a Nobel Prize winner to promote basic research to politicians and business people and, above all, to get children and young people enthusiastic about physics. At times he also expressed himself politically, most recently together with other scientists in an open letter to Chancellor Scholz, in which the continued operation of the last three nuclear power plants, which have since been shut down, was called for. Today Klaus von Klitzing, who is also a member of the order “Pour le Mérite”, celebrates his eightieth birthday.
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