Zeeman-type spin splitting controlled by an electric field

• Main Authors: Shimotani, Hidekazu, Yuan, Hongtao, Mohammad Saeed Bahramy, Morimoto, Kazuhiro, Wu, Sanfeng, Arita, Ryotaro, Nomura, Kentaro, Yang, Bohm-Jung, Suzuki, Ryuji, Toh, Minglin, Xu, Xiaodong, Nagaosa, Naoto, Iwasa, Yoshihiro, Kloc, Christian
• Other Authors: School of Materials Science & Engineering
• Format: Article
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Materials
• Online Access: https://hdl.handle.net/10356/100839; http://hdl.handle.net/10220/16486
• Institution: Nanyang Technological University

Transition-metal dichalcogenides such as WSe2 and MoS2 have electronic band structures that are ideal for hosting many exotic spin–orbit phenomena. Here we investigate the possibility to generate and modulate a giant Zeeman-type spin polarization in WSe2 under an external electric field. By tuning the perpendicular electric field applied to the WSe2 channel with an electric-double-layer transistor, we observe a systematic crossover from weak localization to weak anti-localization in magnetotransport. Our optical reflection measurements also reveal an electrically tunable exciton splitting. Using first-principles calculations, we propose that these are probably due to the emergence of a merely out-of-plane and momentum-independent spin splitting at and in the vicinity of the vertices of the WSe2 Brillouin zone under electric field. The non-magnetic approach for creating such an intriguing spin splitting keeps the system time-reversally invariant, thereby suggesting a new method for manipulating the spin degrees of freedom of electrons.