Spin-polarization anisotropy in bent tungsten diselenide nanoribbons and excitonic states*

Spin-polarization anisotropy in bent tungsten diselenide nanoribbons and excitonic states*

Hong Tang, Santosh Neupane, Li Yin, Jason M. Breslin, and Adrienn Ruzsinszky

Department of Physics, Temple University, Philadelphia, PA 19122

 

A WSe2 monolayer shows many interesting properties due to its spin-orbit coupling induced spin splitting in bands around the Fermi level and the spin-valley configuration [1]. In this work, we studied the WSe2 nanoribbons under different bending curvatures and doping with density functional theory and their optical absorption and excitonic states with many-body perturbation GW and BSE (Bethe-Salpeter equation) methods. We show that the WSe2 nanoribbons can exhibit an enhanced SOC effect and a spatially varying spin polarization in bands around the Fermi level under bending [2]. The spin-polarization can show an anisotropy (or asymmetry) in those nearly degenerate bands, leading to a controllable magnetism with bending.  Electron or hole doping to the nanoribbon suggests a potential application in compact and controllable magnetic nanodevices and spintronics. The optical absorption spectrum of the nanoribbon presents a large tunability with bending within the near infrared region of about 0.4 to 1.5 eV, showing an enhanced absorption at a large bending condition. The exciton states generally show mixed or various spin configuration in the electron and hole pairs, potentially useful for applications in spin-based quantum information processes.   

 

*Work supported by Office of Science, Department of Energy, DE-SC0021263

1 .  Xiao-Xiao Zhang, Ting Cao, Zhengguang Lu, Yu-Chuan Lin, Fan Zhang, Ying Wang, Zhiqiang Li, James C. Hone, Joshua A. Robinson, Dmitry Smirnov, Steven G. Louie and Tony F. Heinz, Magnetic brightening and control of dark excitons in monolayer WSe2, Nature Nanotechnology volume 12, pages883–888 (2017).

2.   Hong Tang, Santosh Neupane, Li Yin, Jason M. Breslin, and Adrienn Ruzsinszky, Spin-polarization anisotropy in bent tungsten diselenide nanoribbons and excitonic states, arXiv    ????