https://doi.org/10.1140/epjb/e2014-41015-8
Regular Article
Nonlinear optical conductivity of two-dimensional semiconductors with Rashba spin-orbit coupling in terahertz regime
1 School of Physics, University of
Wollongong, Wollongong, 2522
NSW,
Australia
2 Key Laboratory of Terahertz Solid
State Technology, Shanghai Institute of Microsystem and Information Technology,
Chinese Academy of Sciences, Shanghai, P.R. China
3 Institute for Superconducting and
Electronic Materials, University of Wollongong, Wollongong, 2522
NSW,
Australia
a
e-mail: c.zhang@uow.edu.au
Received:
17
November
2013
Received in final form:
20
December
2013
Published online:
3
February
2014
We reveal that two-dimensional semiconductors with Rashba spin-orbit interaction (R2DG) exhibit exceptionally strong nonlinear optical response (NOR) in the terahertz frequency regime. The spin-split of the parabolic energy band in R2DG allows strong multiple-photon process to occur via inter-subband mechanism. We show sharp multiple photon edges in the nonlinear conductivity. The edges correspond to the cut-off effect produced by the multiple-photon process. For Rashba coupling parameter of λR ≈ 10-10 eV m, electric field strength in the order of only 102 V/cm is required for the NOR to dominate over the linear response. Furthermore, the roles of the parabolic ‘free electron’ term H0 and the linear Rashba term HR on NOR of R2DG are also investigated. Although the NOR is made possible due to the presence of a finite HR, H0 does play an important role on the NOR especially in high temperature regime. H0 has rendered R2DG a strong optical nonlinearity at elevated temperature which is not found in a purely linear system such as graphene. The results suggest the possibilities of Rashba spintronic system in the application of nonlinear terahertz devices.
Key words: Solid State and Materials
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2014