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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-7976
DTSTART:20221201T160000Z
DURATION:PT1H0M0S
DTSTAMP:20260422T060405Z
LAST-MODIFIED:20221020T221814Z
LOCATION:5310 Chamberlin
SUMMARY:Imaging the Breaking of Electrostatic Dams in Graphene for Bal
 listic and Viscous Fluids\, R. G. Herb Condensed Matter Seminar\,  Zac
 hary Krebs \, UW-Madison
DESCRIPTION:Under special conditions the charge carriers in a material
  can behave as a viscous fluid. In this work\, we investigate such beh
 avior by using scanning tunneling potentiometry to probe the nm-scale 
 flow dynamics of electron fluids in graphene as they pass through cons
 trictions defined by smooth and tunable in-plane p-n junction barriers
 . We observe that as the sample temperature and channel widths are inc
 reased\, the electronic fluid flow undergoes a Knudsen-to-Gurzhi trans
 ition from ballistic to viscous flow that is characterized by a channe
 l conductance that exceeds the ballistic limit\, and suppressed charge
  accumulation against the barriers. Our results are well-modeled by fi
 nite-element simulations of 2D viscous current flow\, and they illustr
 ate how Fermi liquid flow evolves with carrier density\, channel width
 \, and temperature.
URL:https://www.physics.wisc.edu/events/?id=7976
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