Jaarprogramma 2005-2006 | Home

Dinsdag 4 april 2006
prof. dr. C. De Morais-Smith (Instituut Theoretische Fysica, Utrecht)

The magic world of electrons in two dimensions

Low-dimensional systems are a very promising area for the discovery of novel phases that unveil the quantum aspect of nature. At zero and one dimensions, new interesting phenomena have been observed during the last decades, but it is in two dimensions (2D) that a major breakthrough occurred. In the presence of a strong perpendicular magnetic field, electrons moving in 2D will be deviated from their initial trajectory due to the action of the Lorentz force. One may thus measure a transverse resistance in this system, which increases linearly with the magnetic field. This phenomenon was discovered by Hall in 1879 and is called the classical Hall effect. At very low temperatures, however, quantum mechanics comes into play, and new phenomena are observed. The discovery of the “Integral Quantum Hall Effect” (von Klitzing, Nobel Prize 1985) has provided the basis for the most precise resistance standards. But even more remarkably, the “Fractional Quantum Hall Effect” (Tsui, Stormer, and Laughlin, Nobel Prize 1998) has yielded fractional charge, spin and statistics, thus establishing a connection with nuclear and high energy physics. Two decades after these discoveries, quantum Hall systems remain a field of research with unforeseen and surprising phenomena. In this talk, we will present some recent results in this field, as for instance, a competition between electron-solid and electron-liquid phases, as well as the self-similarity exhibited by the Hall resistance curve, in analogy with fractals.

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