Condensed Matter Physics Seminar

2 p.m., Thursday, May 11, 2006
Room 1201, Physics Building

 Electrons in Flatlands: Surprises never stop

Mansour Shayegan

(Princeton University)

Abstract:  The high-mobility two-dimensional electron system, confined to a GaAs quantum well, has provided the testing ground for some of the most exciting phenomena in solid state physics. Cooled to low temperatures and subjected to a perpendicular magnetic field, this system has led to the observation of new, often completely unexpected, electronic states. Examples include the fractional quantum Hall state, charge density modulated states (striped phases), charge-flux composite Fermions, and states with unusual spin-texture (Skyrmions). In this presentation, I will talk about a rather unusual flatland, namely a modulation-doped AlAs quantum well, where the electrons occupy multiple conduction-band valleys in different parts of the Brillouin zone. The additional (valley) degree of freedom adds interesting twists and leads to new phenomena. Highlights will be the results of our spin and valley susceptibility measurements in multi-valley systems and the dominant role that interaction plays in these parameters, and our observation of “valley” Skyrmions.
Host:  Drew
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