BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:4
UID:UW-Physics-Event-6568
DTSTART:20210826T150000Z
DURATION:PT1H0M0S
DTSTAMP:20260414T192100Z
LAST-MODIFIED:20210825T203827Z
LOCATION:Chamberlin 2103
SUMMARY:Imaging work and dissipation in the quantum Hall state of grap
 hene\, R. G. Herb Condensed Matter Seminar\, Arthur
DESCRIPTION:Dissipationless topologically protected states are of majo
 r interest as well as of practical importance in metrology and quantum
  information technology. Although topological protection can be robust
  theoretically\, in realistic devices it is often fragile against vari
 ous dissipative mechanisms\, which are difficult to probe directly bec
 ause of their microscopic origins. By utilizing scanning nanothermomet
 ry [1]\, we visualized and investigated microscopic mechanisms undermi
 ning the topological protection in the quantum Hall state in graphene.
  Our simultaneous nanoscale thermal and scanning gate microscopy enabl
 es to identify two distinct and spatially separated scattering process
 es. I will show how these observations reveal that the dissipation is 
 governed by a crosstalk between counter-propagating pairs of channels 
 that appear at graphene boundaries because of edge reconstruction due 
 to charge accumulation at the edges[2].
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\n 
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\nTime permitting\, 
 I will present a semi-classical transport model quantifying the effect
  of edge accumulation under moderate magnetic fields and in particular
  the strikingly high non-local voltages it generates[3]. I will discus
 s its implication for Hall measurements in particular in the case of c
 harge-neutral graphene.
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\n 
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\nReferences :
\n
\n[1] D. Halbertal
 \,et al.\, Nature 539\, 407-410(2016)
\n
\n[2] A. Marguerite\, et al.\
 , Nature 575\, 628-633 (2019)
\n
\n[3] A. Aharon-Steinberg\, et al.\, 
 Nature 593\, 528-534 (2021)
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\n
\nSemin
 ar can also be viewed virtually at:  https://uwmadison.zoom.us/j/96688
 28685
\n
URL:https://www.physics.wisc.edu/events/?id=6568
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