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URL:https://www.calendrier.umontreal.ca/detail/881642-higher-order-topologi
cal-insulators-under-strong-magnetic-fields-benjamin-a-levitan-mcgill
LOCATION:Chez vous - par ZOOM\, QC\, Canada
SUMMARY:Higher-order topological insulators under strong magnetic fields -
Benjamin A. Levitan (McGill)
DESCRIPTION:Higher-order topological insulators under strong magnetic field
sBenjamin A. LevitanPhysics DepartmentMcGill Universitysuperviser: Tami Pe
reg-Barnea
\nPrésentation en anglais
\nVidéoconférence\, Zomm #: 89201
9835 (Zoom link)Lorsque demandé\, indiquer 'zéro zéro deux quatre sept
deux' en chiffre.
\nAbstract: The family tree of topological insulators ha
s blossomed vigorously since their initial prediction and discovery in the
2000s. Higher-order topological insulators are the youngest branch on thi
s tree. Like their more familiar (first-order) cousins\, these materials a
re fully-gapped insulators in the bulk. Their “higher-order” topologic
al nature is reflected in their bulk-boundary correspondence: in D spatial
dimensions\, an n-th order topological insulator will have in-gap states
localized to (D-n)-dimensional pieces of its boundary\, protected by a com
bination of symmetry and topology.
\nWe study the response of a three-dime
nsional second-order topological insulator (with one-dimensional chiral me
tallic “hinge” modes) to an applied magnetic field. We derive an effec
tive surface theory which accurately captures several key qualitative feat
ures of its underlying bulk lattice model\, including massive Dirac fermio
ns\, Landau levels\, and chiral hinge modes. We find that the full lattice
model predicts a lowest Landau level closer to zero energy than would be
expected from the surface theory. As a result\, within the surface gap\, t
here exist different regions of energy\, within which either one or two ch
iral hinge modes propagate in either direction. This directly leads to an
observable magnetotransport signature: as one scans across the surface gap
\, the differential conductance of a rectangular nanowire steps between on
e and two conductance quanta.
\nRef: B.A. Levitan and T. Pereg-Barnea\, ar
Xiv:2004.05652 [cond-mat.mes-hall]\, 2020 (with referees @ PRR)
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