Chiral tunneling modulated by a time-periodic potential on the surface states of a topological insulator.
Time-periodic perturbation can be used to modify the transport properties of the surface states of topological insulators, specifically their chiral tunneling property. Using the scattering matrix method, we study the tunneling transmission of the surface states of a topological insulator under the influence of a time-dependent potential and finite gate bias voltage. It is found that perfect transmission is obtained for electrons which are injected normally into the time-periodic potential region in the absence of any bias voltage. However, this signature of Klein tunneling is destroyed when a bias voltage is applied, with the transmission probability of normally incident electrons decreasing with increasing gate bias voltage. Likewise, the overall conductance of the system decreases significantly when a gate bias voltage is applied. The characteristic left-handed helicity of the transmitted spin polarization is also broken by the finite gate bias voltage. In addition, the time-dependent potential modifies the large-angle transmission profile, which exhibits an oscillatory or resonance-like behavior. Finally, time-dependent transport modes (with oscillating potential in the THz frequency) can result in enhanced overall conductance, irrespective of the presence or absence of the gate bias voltage.
1] Department of Physics, Hangzhou Dianzi University, Hangzhou, Zhejiang 310018, China [2] Department of Electronic and Computer Engineering, Information Storage Materials Laboratory, National University of Singapore, 1 Engineering Drive 3, Singapore 117576, Singapore.
Yuan
Y
Li
Department of Electronic and Computer Engineering, Information Storage Materials Laboratory, National University of Singapore, 1 Engineering Drive 3, Singapore 117576, Singapore.
Mansoor B A
MB
Jalil
Department of Electronic and Computer Engineering, Information Storage Materials Laboratory, National University of Singapore, 1 Engineering Drive 3, Singapore 117576, Singapore.
S G
SG
Tan
Department of Physics, Hangzhou Dianzi University, Hangzhou, Zhejiang 310018, China.
W
W
Zhao
Center for Integrated Spintronic Devices (CISD), Hangzhou Dianzi University, Hangzhou, Zhejiang 310018, China.
R
R
Bai
Department of Physics and Key Laboratory for Low-Dimensional Quantum Structures and Manipulation (Ministry of Education), Hunan Normal University, Changsha 410081, China.
G H
GH
Zhou