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CATEGORIES:Theory of Condensed Matter
SUMMARY:Topological order from strong correlations in two-
dimensional lattice models - Stefanos Kourtis\, IF
W Dresden
DTSTART;TZID=Europe/London:20140508T141500
DTEND;TZID=Europe/London:20140508T151500
UID:TALK50124AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/50124
DESCRIPTION:The formation of fractional quantum-Hall (FQH) sta
tes in lattice systems without externally applied
magnetic fields -- dubbed fractional Chern insulat
ors (FCI) -- is a recent and promising theoretical
proposal that has the potential to render the FQH
effect experimentally more accessible. The paradi
gmatic FCIs are found when interacting electrons w
ith frozen spin degree of freedom populate relativ
ely flat topological bands\, with the interaction
strength being smaller than the gap to other bands
. In this talk\, I will show that this limit is ad
iabatically connected to the opposite one\, in whi
ch the interaction strength goes to infinity\, thu
s exceeding the gap to other bands. Electrons then
become extended hard-core particles\, the notion
of bands becomes meaningless and the connection to
Landau level physics of the fractional quantum-Ha
ll effect is much less obvious. FCI states are ver
y robust in this hardcore limit\, reaching up to\,
or possibly beyond\, the non-interacting topologi
cal phase transition. Strong interactions may also
give rise to competition between topological and
conventional charge order. After discussing this c
ompetition\, I will introduce a class of states in
which the FCI topological order is induced by the
presence of a charge-density wave and will presen
t numerical evidence for this coexistence. Finally
\, based on these compositely ordered states\, I w
ill provide a recipe for topological order out of
a topologically trivial band structure.
LOCATION:TCM Seminar Room\, Cavendish Laboratory
CONTACT:Dr G Moller
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