P-A Colloquium: Probing Exotic States of Interacting 2D Electron Systems

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Speaker:  Mansour Shayegan, Princeton University

Title:  Probing Exotic States of Interacting 2D Electron Systems

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Refreshments at 3:30 pm in 1400 BPS.

Date: Thu, 11 Oct 2018, 4:10 pm – 5:10 pm
Type: Colloquium
Location: 1415 BPS Bldg.

Abstract:
There has been a surge of recent interest in the physics of interacting 2D electrons in a large perpendicular magnetic field when they occupy a half-filled Landau level. The long ago pro­posed composite fer­mion (CF) pic­ture, in which two mag­netic flux quanta are bound to each elec­tron to form a CF, explains many properties of the system. These in­clude the com­pressible (metallic) behavior of the 2D system at filling factor ν = ½, the exist­ence of a Fermi con­tour with a well-defined Fermi wave vec­tor, and the presence of frac­tional quan­tum Hall states as the filling deviates from ν = ½. In this talk, I will high­light the results of sev­eral recent experi­ments, per­formed on very high mobility 2D elec­tron and hole systems confined to GaAs/AlGaAs quan­tum wells, that probe CFs via measuring the geomet­ric reso­nance of their cyclo­tron orbit diameter with the period of an im­posed, uni­directional den­sity modula­tion.