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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:4
UID:UW-Physics-Event-7907
DTSTART:20230203T213000Z
DTEND:20230203T223000Z
DTSTAMP:20260414T033220Z
LAST-MODIFIED:20230202T142856Z
LOCATION:2241 Chamberlin Hall
SUMMARY:Multi-messenger scanning probe microscopy for the investigatio
 n of electronic properties of materials.\, Physics Department Colloqui
 um\, Victor Brar\, UW Madison
DESCRIPTION:Scanning probe microscopy is an imaging technique whereby 
 a sharp tip is moved across a surface while locally measuring some mat
 erial property with a resolution that can be sub-Angstrom.   A wide ra
 nge of material properties can be studied in this way\, including surf
 ace conductance (scanning tunneling microscopy)\, physical structure (
 atomic force microscopy)\, and surface potential (Kelvin probe force m
 icroscopy).   By combining these measurement techniques\, a complete u
 nderstanding of a material's properties can be developed that relates 
 electron motion to underlying atomic structure.  In this talk I will s
 how how multiple scanning probe measurements can be performed on graph
 ene to reveal how electrons scatter off and move around in-plane poten
 tial barriers formed by charged defects. By comparing measurements of 
 the spatially varying surface potential with measurements of the elect
 ron wavefunction\, the electron dynamics can be modeled precisely\, an
 d described using a single-particle wavefunction.  As the electron tem
 perature is increased\, however\, these measurements reveal a new hydr
 odynamic phase of the electron fluid emerges with a viscosity comparab
 le to diesel fuel.  Our scanned probe measurements show that this new 
 phase exhibits a conductivity that is greater than ballistic conductan
 ce\, and that the motion of electrons around barriers resembles that o
 f water moving around pebbles in a stream. 
URL:https://www.physics.wisc.edu/events/?id=7907
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