关键词: 二硫化钼/
非共振圆偏振光/
电子结构/
自旋/谷霍尔电导
English Abstract
Electronic structure and spin/valley transport properties of monolayer MoS2 under the irradiation of the off-resonant circularly polarized light
Zhang Xin-Cheng,Liao Wen-Hu,
Zuo Min
1.College of Physics, Mechanical and Electrical Engineering, Jishou University, Jishou 416000, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant Nos. 11664010, 11264013), the Hunan Provincial Natural Science Foundation of China (Grant Nos. 2017JJ2217, 12JJ4003), the Scientific Research Fund of Hunan Provincial Education Department of China (Grant No. 14B148), and the Research Program of Jishou University, China (Grant Nos. JGY201763, Jdy16021).Received Date:28 January 2018
Accepted Date:05 March 2018
Published Online:20 May 2019
Abstract:The new-type monolayer semiconductor material molybdenum disulfide (MoS2) is direct band gap semiconductor with a similar geometrical structure to graphene, and as it owns superior physical features such as spin/valley Hall effect, it should be more excellent than graphene from the viewpoint of device design and applications. The manipulation of the spin and valley transport in MoS2-based device has been an interesting subject in both experimental and theoretical researches. Experimentally, the photoninduced quantum spin and valley Hall effects may result in high on-off speed spin and/or valley switching based on MoS2. Theoretically, the off-resonant electromagnetic field induced Floquet effective energy should modulate effectively the electronic structure, spin/valley Hall conductance as well as the spin/valley polarization of the MoS2, through the virtual photon absorption and/or emission processes. Utilizing the low energy effective Hamilton model from the tight-binding approximation and Kubo linear response theorem, we theoretically investigate the electronic structure and spin/valley transport properties of the monolayer MoS2 under the irradiation of the off-resonant circularly polarized light in the present work. The band gaps around the K and K' point of the Brillouin region for monolayer MoS2 proves to increase linearly and decrease firstly and then increase, respectively with the increase of external off-resonant right-circularly polarized light induced effective coupling energy, and decrease firstly and then increase and increase linearly with the increase of left-circularly polarized light induced effective coupling energy, therefore, the interesting transition of semiconducting-semimetallic-semiconducting may be observable in monolayer MoS2. Furthermore, the spin and valley Hall conductance of the monolayer MoS2 for the case without off-resonant circularly polarized light are 0 and 2e2/h, respectively, and they will convert into -2e2/h and 0 when the absolute value of the off-resonant circularly polarized light induced effective coupling energy is in a range of 0.79-0.87 eV. Finally, the spin polarization for monolayer MoS2 increases up to a largest value and changes from positive to negative and/or negative to positive at the vicinity of the effective coupling energy ±0.79 eV of the off-resonant right/left circularly polarized light, while the valley polarization should increase firstly and then decrease with the off-resonant circularly polarized light, and goes up to 100% in the range of 0.79-0.87 eV of the absolute value for effective coupling energy. Therefore, the external off-resonant circularly polarized electromagnetic field should be an effective means in manipulating the electronic structure, spin/valley Hall conductance and spin/valley polarization of the monolayer MoS2, the two-dimensional MoS2 may be tuned into a brand bandgap material with excellent spin/valley and optoelectrical properties.
Keywords: MoS2/
off-resonant light/
electronic structure/
spin/valley Hall conductance
