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VERSION:2.0
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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-3410
DTSTART:20141023T150000Z
DTEND:20141023T160000Z
DTSTAMP:20260419T161613Z
LAST-MODIFIED:20141013T194334Z
LOCATION:Chamberlin 5310
SUMMARY:New Topological Excitations and Melting Transitions in Quantum
  Hall Effect\, R. G. Herb Condensed Matter Seminar\, Yuli Lyanda-Gelle
 r\, Purdue University
DESCRIPTION:Topology and symmetry define states of matter and their re
 sponses to external forces. How solids melt and become fluids\, or how
  insulators become conductors is often controlled by excitations rathe
 r than by the ground state of systems. Non-trivial topology of excitat
 ions can alter the responses. Topological excitations are notoriously 
 difficult to predict since they cannot be obtained as a perturbation o
 f the ground state. In this talk I will report the discovery of a new 
 type of topological excitations that arise in two-dimensional electron
  systems in a magnetic field. We investigate Landau level filling fact
 ors between integer and half-integer\, which exhibit the re-entrant in
 teger quantum Hall effect (RIQHE) with vanishing longitudinal resistan
 ce and the Hall resistance quantized to a nearest integer at lowest te
 mperatures. I will show that charge excitations in the RIQHE regime ar
 e topologically non-trivial finite size textures of electron density w
 ith charge-dependent symmetry. These topological textures explain unus
 ual strain dependence of resistivity. At low temperatures\, the textur
 es form a crystal\, whose melting leads to metal-insulator transition.
URL:https://www.physics.wisc.edu/events/?id=3410
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