Klaus von Klitzing

Physicist — Klaus von Klitzing (Środa Wielkopolska, 1943) is a German physicist, Nobel laureate in physics in 1985. Trained and active in Germany, he now heads a Max Planck institute in Stuttgart. In 1980 he discovered the quantum Hall effect: studying the behaviour of electrons in a thin conducting layer at very low temperature and in an intense magnetic field, he observed that the Hall resistance takes on quantised values with extraordinary precision, in exact steps independent of the details of the material. This discovery revealed a new quantum state of matter and provided a resistance-measurement method so precise that it was adopted as a standard. The von Klitzing constant is now used to define the standard of electrical resistance.

Trivia

Thanks to the precision of the quantum Hall effect, since 2019 the redefinition of the International System of Units has used the von Klitzing constant to fix the ohm; the discovery came to von Klitzing after a night of measurements in a laboratory in Grenoble.

Theories and contributions

• Quantum Hall effect — At low temperatures and in an intense magnetic field, the Hall resistance is quantised: $R_H = \frac{h}{i e^2}$, with $i$ an integer.
• Von Klitzing constant — Fundamental quantum of resistance: $R_K = \frac{h}{e^2} \approx 25\,813\,\Omega$, used as a standard.

Featured in chapters

17

Linked atoms

1 linked atoms.

17 Il campo magnetico

• The Hall effect