Observation of the possible chiral edge mode in Bi1−xSbx

After the classification of topological states of matter has been clarified for non-interacting electron systems, the theoretical connection between gapless boundary modes and nontrivial bulk topological structures, and their evolutions as a function of dimensions are now well understood. However, s...

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Bibliographic Details
Published in:New journal of physics 2018-07, Vol.20 (7), p.073038
Main Authors: Sasaki, M, Ohnishi, A, Das, Nabyendu, Kim, K-S, Kim, Heon-Jung
Format: Article
Language:English
Subjects:
alloy
Bi1−xSbx alloy
bulk-edge correspondence
chiral edge mode
Chirality
dimensional hierarchy
Magnetic fields
Physics
Quantum Hall effect
Resistance
Time dependence
topological insulator
Topological insulators
Topology
transient thermoelectric voltages
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Summary:After the classification of topological states of matter has been clarified for non-interacting electron systems, the theoretical connection between gapless boundary modes and nontrivial bulk topological structures, and their evolutions as a function of dimensions are now well understood. However, such dimensional hierarchy has not been well established experimentally although some indirect evidences were reported, for example, such as the half-quantized Hall conductance via quantum Hall effect and extrapolation in the quantum-oscillation measurement. In this paper, we report the appearance of the possible chiral edge mode from the surface state of topological insulators under magnetic fields, confirming the dimensional hierarchy in three-dimensional topological insulators. Applying laser pulses to the surface state of Bi1−xSbx, we find that the sign of voltage relaxation in one edge becomes opposite to that in the other edge only when magnetic fields are applied to the topological insulating phase. We show that this sign difference originates from the chirality of edge states, based on coupled time-dependent Poisson and Boltzmann equations.
ISSN:1367-2630
DOI:10.1088/1367-2630/aad03c