The top 500 results for "Klitzing" are:

The quantum mechanical description of a spontaneous emission of phonons is presented to derive a critical current, which destroys the non-dissipative current in the regime of the quantum Hall effect.

Measurements of the Hall potential distribution in quantum Hall effect experiments lead to the conclusion that the current distribution within the two-dimensional system is strongly inhomogeneous and has no similarity with the calculated distribution for an ideal system.

This paper describes a recent determination of the von Klitzing constant and the fine-structure constant by comparisons of values of the ohm as defined in the International System of Units (SI), derived from the National Institute of Standards and Technology (NIST) calculable cross-capacitor, and values of the international practical unit of resistance derived from the integral quantum Hall effect. In this determination, the comparisons were made in a series of measurements lasting three years. A small difference is observed between this determination and an earlier comparison carried out in this laboratory and reported in 1988. The most recent value of the fine-structure constant based on the experimental value and theoretical expression for the magnetic moment anomaly of the electron, which has the smallest uncertainty of any value currently available, is consistent with both of these results. The new value exceeds the 1990 conventional value of the von Klitzing constant R_K-90 by slightly more than twice the relative standard uncertainty of the present measurement, which is 2.4 × 10^-8.

The von Klitzing constant R_K has been previously determined at the Bureau National de Métrologie (BNM) in 1986 and 1993. Considering the recommendation of the Comité Consultatif d'Electricité working group on the quantum Hall effect in 1988, as well as the differences between the values of the fine structure constant obtained from different methods, it appears to be particularly important that we continue to develop and improve the direct determinations of R_K.

Since 1993, the BNM calculable capacitor, comparison bridges and transfer standards have been considerably modified and the value was determined anew in 1999–2000. The result is R_K = R_K−90×(1 + 4.1 × 10⁻⁸) (1σ = 5.3×10⁻⁸)

This paper describes the different investigations, modifications and characterizations of the measurement chain elements that were carried out during the last fifteen years in order to obtain this result.

Without abstract; see full text.

Tunnelling through single and coupled GaAs quantum dots is used to analyse the electronic properties of artificial atoms and molecules. In addition we demonstrate that a strongly localized dot can be used as a spectrometer with high spatial and energy resolution for the determination of the local density of states in a disordered semiconductor.

Erratum for Europhys. Lett. 28 (2) 129-134 (1994).

The Fermi energy and the Zeeman splitting of composite fermions are measured from the temperature dependence of the electron spin polarization at v = 1/2. We demonstrate that the Zeeman splitting of composite fermions is enhanced by a factor of 2.5 due to the interaction between CFs. The latter is very sensitive on the finite width of the 2D channel. The spin polarization at v = 1/3 and v = 2/3 displays an activated behavior and the derived spin-wave gaps are compared with simultaneously measured transport values.

Measurements of the conductivity sigma _xx in the minima of the Shubnikov-de Haas oscillations on GaAs-Al_xGa_1-xAs heterostructures show that at helium temperatures a strong non-ohmic behaviour is observed with an instability in the current-voltage characteristic at electric field values of about 100 V cm^-1 at B=7T. The data are analysed on the basis of an electric-field-dependent electron temperature.

Addition gaps in the energy spectrum of a two-dimensional electron gas in a strong magnetic field due to electron-electron interaction seem to be responsible for the fractional quantum Hall effect (FQHE). The authors have analysed the structures attributed to the FQHE in the components rho _xx, rho _xy and sigma _xx of the resistivity and conductivity tensor as a function of the magnetic field at Landau filling factors up to nu =3. For the first time the values for the energy gaps at nu =⁴/₃ and nu =⁵/₃ are determined and resistivity values for the corresponding Hall plateaux are reported.