Simple Design of Topological State
DIPC Seminars
 Speaker

Xiao Hu (International Center for Materials Nanoarchitectonics (WPIMANA) National Institute for Materials Science (NIMS), Tsukuba, Japan)
 When

2015/07/06
14:00  Place
 Donostia International Physics Center (DIPC)
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Simple Design of Topological State
Xiao HU
International Center for Materials Nanoarchitectonics (WPIMANA)
National Institute for Materials Science (NIMS), Tsukuba, Japan
**Abstr** **act**
How simple can a useful topological system be? In this talk I try to answer
this question based on our recent work on achieving quantum spin Hall effects
by simply deforming honeycomb lattice. We observe that honeycomb lattice is
equivalent to triangle lattice of hexagons formed by six neighboring sites.
When the triangle lattice is squeezed with the hexagons fixed and C6 symmetry
preserved, a gap will be opened in the Dirac energy dispersion, and
simultaneously a pseudo spin degree of freedom will be generated in the
system. The first implementation of this idea is a topological photonic
crystal based on conventional dielectric material, such as silicon, which
carries on edge counterpropagation of electromagnetic waves with opposite
pseudo spins. In the second example, we modify the electron hopping integral
between nearestneighboring sites of honeycomb lattice in a way to build
Kekule hopping texture. It is shown that an effective spinorbit coupling
(SOC) is generated, larger than the intrinsic SOC by several orders of
magnitude, which may make helical edge currents available at high temperature.