BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Physics-TWaP
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-4246
DTSTART:20161208T160000Z
DURATION:PT1H0M0S
DTSTAMP:20201030T200918Z
LAST-MODIFIED:20161201T023709Z
LOCATION:Chamberlin 5310
SUMMARY:Universal transport at the edge: Disorder\, interactions\, and
topological protection\, R. G. Herb Condensed Matter Seminar\, Matthe
w Foster\, Rice University
DESCRIPTION:Topological insulators and superconductors provide condens
ed matter realizations of the holographic principle: a topological pro
perty of the bulk translates into an anomalous time-reversal symmetry
at the material surface. This symmetry underlies "topological protecti
on" of the edge or surface states. Protection from disorder effects (A
nderson localization) is particularly nontrivial\, because surfaces ar
e low dimensional. While this was previously understood for noninterac
ting models of edge and surface states\, the more complicated problem
of combined disorder and interaction effects had not been addressed un
til recently. I will discuss two different examples of universal edge
or surface transport that arise in the presence of both. First\, I wil
l consider the edge states of 2D topological insulators with Rashba sp
in-orbit coupling (RSOC). With RSOC\, disorder induces a backscatterin
g term in the edge theory. We have shown that transport remains perfec
tly ballistic in a model that incorporates this term and interactions.
The solution involves a mapping to spin 1/2 moment that executes perf
ect adiabatic evolution in a random magnetic field. [1] Second\, I wil
l discuss the surface states of 3D topological superconductors\, and e
xplain why we predict universal surface thermal and (if conserved) spi
n conductivities. The solution combines various nonperturbative and/or
exact methods including conformal field theory\, the Finkel'stein non
-linear sigma model\, and numerics. [2\,3] I will also show how disord
er enhances topological protection for surface states of recently intr
oduced [4] model spin-3/2 topological superconductors\, which may have
applications to ultracold atoms or Half-Heusler compounds.

\n

\nRefs:

\n[1] H.-Y. Xie\, H. Li\, Y.-Z. Chou\, and M. S. Foster\
, PRL 116\, 086603 (2016)

\n[2] H.-Y. Xie\, Y.-Z. Chou\, and M. S.
Foster\, PRB 91\, 024203 (2015)

\n[3] M. S. Foster\, H.-Y. Xie\,
and Y.-Z. Chou\, PRB 89\, 155140 (2014)

\n[4] W. Yang\, Yi Li\, an
d C. Wu\, PRL 117\, 075301 (2016)

\n
URL:https://www.physics.wisc.edu/twap/?id=4246
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