The quantum Hall effects

Autori

• Tapash Chakraborty

Parametri

• Fisica
• Scienze Naturali
• Springer series in solid-state sciences

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The fractional quantum Hall effect (FQHE) was unexpectedly discovered in 1981 by Tsui, Stormer, and Gossard, despite the lack of theoretical predictions for new structures in magnetotransport coefficients under extreme quantum conditions. Over thirty years of research on bulk semiconductors in strong magnetic fields revealed that only the lowest Landau level is occupied, leading to a predicted monotonic resistivity variation with increasing magnetic field, influenced by scattering mechanisms. However, experimental data analysis was complicated by magnetic freeze-out effects and transitions between degenerate and nondegenerate systems. In two-dimensional electron systems, the positive background charge is well-separated, making magnetic freeze-out effects less pronounced and data analysis in the extreme quantum limit easier. Initial measurements on silicon field-effect transistors failed due to significant disorder, which localized all electrons in the lowest Landau level. This led to the development of models like spin glass and Wigner solid, alongside efforts to enhance the quality of semiconductor materials and devices, particularly in two-dimensional electron systems.

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Lingua: Tedesco

Pubblicato: 1995