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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-1587
DTSTART:20091001T150000Z
DURATION:PT1H0M0S
DTSTAMP:20260313T050148Z
LAST-MODIFIED:20090818T142158Z
LOCATION:5310 Chamberlin
SUMMARY:Dephasing and disorder effects in quantum spin Hall effect\, R
 . G. Herb Condensed Matter Seminar\, Xincheng Xie\, Oklahoma State Uni
 versity
DESCRIPTION:The influence of dephasing on the quantum spin Hall effect
  (QSHE) is studied. In the absence of dephasing\, the longitudinal res
 istance in a QSHE system exhibits the quantum plateaus. We find that t
 hese quantum plateaus are robust against the normal dephasing but frag
 ile with the spin dephasing. Thus\, these quantum plateaus only surviv
 e in mesoscopic samples. Moreover\, the longitudinal resistance increa
 ses linearly with the sample length but is insensitive to the sample w
 idth. These characters are in excellent agreement with the recent expe
 rimental results [Science 318\, 766 (2007)]. In addition\, we define a
  new spin Hall resistance that also exhibits quantum plateaus. In part
 icular\, these plateaus are robust against any type of dephasing and t
 herefore\, survive in macroscopic samples and better reflect the topol
 ogical nature of QSHE.<br>
\n<br>
\nIn addition\, we also study the di
 sorder effect on the transport properties in QSHE. We confirm that at 
 a moderate disorder strength\, the initially un-quantized two terminal
  conductance becomes quantized\, and the system makes a transition to 
 the novel topological Anderson insulator (TAI). Conductances calculate
 d for the stripe and cylinder samples reveal the topological feature o
 f TAI and supports the idea that the helical edge states may cause the
  anomalous quantized plateaus. The influence of disorder is studied by
  calculating the distributions of local currents. Base on the above-me
 ntioned picture\, the phenomena induced by disorder in the quantum spi
 n Hall region and TAI region are directly explained.
URL:https://www.physics.wisc.edu/events/?id=1587
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