Finite size effects on helical edge states in a quantum spin-Hall system.
The hallmark of the spin-Hall insulator is the presence of gapless edge states of different spins moving in opposite directions. Through analytical solutions in a model calculation for a strip of finite width, we find that edge states on the two sides can couple together to produce a gap in the spectrum, destroying the quantum spin-Hall effect. The application of a magnetic field can however modify and even remove the gap by shifting the momenta of the edge states relative to each other.
Zhou
Bin
B
Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
Lu
Hai-Zhou
HZ
Chu
Rui-Lin
RL
Shen
Shun-Qing
SQ
Niu
Qian
Q