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SUMMARY: Topological quantum paramagnet in quantum spin systems
DTSTART;VALUE=DATE-TIME:20171130T090000Z
DTEND;VALUE=DATE-TIME:20171130T100000Z
DTSTAMP;VALUE=DATE-TIME:20180118T000401Z
UID:indico-event-6056@cern.ch
DESCRIPTION:Topological quantum paramagnets are exotic states of matter wi
th trivial paramagnetic ground states hosting topological excitations. We
show that in the presence of spin-orbit coupling a quantum spin ladder hos
ts a topological quantum paramagnet (TQP). This phase has fractional excit
ations localized at the ends of the ladder. The excitation spectrum is top
ologically non-trivial and is characterized by a non-zero winding number.
We discuss possible experimental signatures to detect this exotic phase. A
s another example\, we show that a simple model of quantum spins on a hone
ycomb bilayer hosts a Z2 TQP in the presence of spin-orbit coupling. The Z
2 invariant is the same as that in the case of the fermionic quantum spin
Hall state. We further show that upon making one of the Heisenberg couplin
gs stronger the system undergoes a topological quantum phase transition\,
where the Z2 invariant vanishes\, to a different TQP. In this case the edg
e states are disconnected from the bulk excitations and the phase is chara
cterized by a different topological invariant. This physics is amenable to
experiments\, where an anisotropic coupling can be induced under pressure
.\n\nhttps://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6056
LOCATION: A304
URL:https://indico.tifr.res.in/indico/conferenceDisplay.py?confId=6056
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