2,642 research outputs found
Quantum spin Hall effect induced by electric field in silicene
We investigate the transport properties in a zigzag silicene nanoribbon in
the presence of an external electric field. The staggered sublattice potential
and two kinds of Rashba spin-orbit couplings can be induced by the external
electric field due to the buckled structure of the silicene. A bulk gap is
opened by the staggered potential and gapless edge states appear in the gap by
tuning the two kinds of Rashba spin-orbit couplings properly. Furthermore, the
gapless edge states are spin-filtered and are insensitive to the non-magnetic
disorder. These results prove that the quantum spin Hall effect can be induced
by an external electric field in silicene, which may have certain practical
significance in applications for future spintronics device.Comment: 4 pages, 5 figure
Pure spin current in a two-dimensional topological insulator
We predict a mechanism to generate a pure spin current in a two-dimensional
topological insulator. As the magnetic impurities exist on one of edges of the
two-dimensional topological insulator, a gap is opened in the corresponding
gapless edge states but another pair of gapless edge states with opposite spin
are still protected by the time-reversal symmetry. So the conductance plateaus
with the half-integer values can be obtained in the gap induced by
magnetic impurities, which means that the pure spin current can be induced in
the sample. We also find that the pure spin current is insensitive to weak
disorder. The mechanism to generate pure spin currents is generalized for
two-dimensional topological insulators.Comment: 5 pages, 6 figure
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