title: Nonlinear Rashba spin splitting in transition metal dichalcogenide monolayers.
abstract: Single-layer transition-metal dichalcogenides (TMDs) such as MoS2and MoSe2exhibit unique electronic band structures ideal for hosting many exotic spin-orbital orderings. It has been widely accepted that Rashba spin splitting (RSS) is linearly proportional to the external field in heterostructure interfaces or to the potential gradient in polar materials. Surprisingly, an extraordinary nonlinear dependence of RSS is found in semiconducting TMD monolayers under a gate field. In contrast to small and constant RSS in polar materials, the potential gradient in non-polar TMDs gradually increases with the gate bias, resulting in nonlinear RSS with a Rashba coefficient an order-of-magnitude larger than the linear one. Most strikingly, under a large gate field MoSe2demonstrates the largest anisotropic spin splitting among all known semiconductors to our knowledge. Based on the k·p model via symmetry analysis, we identify that the third-order contributions are responsible for the large nonlinear Rashba splitting. The gate tunable spin splitting found in semiconducting pristine TMD monolayers promises future spintronics applications in that spin polarized electrons can be generated by external gating in an experimentally accessible way.
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China. jtsun@iphy.ac.cn and College of Physical Science and Technology, Sichuan University, Chengdu 610064, China. xrchen@scu.edu.cn.
authors.forename: Cai
authors.initials: C
authors.lastname: Cheng
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China. jtsun@iphy.ac.cn.
authors.forename: Jia-Tao
authors.initials: JT
authors.lastname: Sun
authors.affiliation: College of Physical Science and Technology, Sichuan University, Chengdu 610064, China. xrchen@scu.edu.cn.
authors.forename: Xiang-Rong
authors.initials: XR
authors.lastname: Chen
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China. jtsun@iphy.ac.cn.
authors.forename: Hui-Xia
authors.initials: HX
authors.lastname: Fu
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China. jtsun@iphy.ac.cn and School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China. smeng@iphy.ac.cn.
authors.forename: Sheng
authors.initials: S
authors.lastname: Meng