title: Evolution of the Valley Position in Bulk Transition-Metal Chalcogenides and Their Monolayer Limit.
abstract: Layered transition metal chalcogenides with large spin orbit coupling have recently sparked much interest due to their potential applications for electronic, optoelectronic, spintronics, and valleytronics. However, most current understanding of the electronic structure near band valleys in momentum space is based on either theoretical investigations or optical measurements, leaving the detailed band structure elusive. For example, the exact position of the conduction band valley of bulk MoS2 remains controversial. Here, using angle-resolved photoemission spectroscopy with submicron spatial resolution (micro-ARPES), we systematically imaged the conduction/valence band structure evolution across representative chalcogenides MoS2, WS2, and WSe2, as well as the thickness dependent electronic structure from bulk to the monolayer limit. These results establish a solid basis to understand the underlying valley physics of these materials, and also provide a link between chalcogenide electronic band structure and their physical properties for potential valleytronics applications.
authors.affiliation: Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States.|Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Hongtao
authors.initials: H
authors.lastname: Yuan
authors.affiliation: Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States.|Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.|School of Physical Science and Technology, ShanghaiTech University , Shanghai 200031, China.|CAS-Shanghai Science Research Center , 239 Zhang Heng Road, Shanghai 201203, China.
authors.forename: Zhongkai
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States.
authors.forename: Gang
authors.initials: G
authors.lastname: Xu
authors.affiliation: Physics Department, Clarendon Laboratory, University of Oxford , Parks Road, Oxford OX1 3PU, United Kingdom.|Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhou
authors.affiliation: Department of Physics, Department of Materials Science and Engineering, University of Washington , Seattle, Washington 98195, United States.
authors.forename: Sanfeng
authors.initials: S
authors.lastname: Wu
authors.affiliation: Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology , Taipei 106, Taiwan (ROC).|Electrical Engineering Institute, Ecole Polytechnique Federale de Lausanne (EPFL) , CH-1015 Lausanne, Switzerland.
authors.forename: Dumitru
authors.initials: D
authors.lastname: Dumcenco
authors.affiliation: Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States.|Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Kai
authors.initials: K
authors.lastname: Yan
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Sung-Kwan
authors.initials: SK
authors.lastname: Mo
authors.affiliation: Diamond Light Source , Didcot, Oxfordshire OX11 0BW, United Kingdom.
authors.forename: Pavel
authors.initials: P
authors.lastname: Dudin
authors.affiliation: Elettra-Sincrotrone Trieste ScPA , Trieste, Basovizza 34149, Italy.
authors.forename: Victor
authors.initials: V
authors.lastname: Kandyba
authors.affiliation: Elettra-Sincrotrone Trieste ScPA , Trieste, Basovizza 34149, Italy.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Yablonskikh
authors.affiliation: Elettra-Sincrotrone Trieste ScPA , Trieste, Basovizza 34149, Italy.
authors.forename: Alexei
authors.initials: A
authors.lastname: Barinov
authors.affiliation: Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States.|Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Zhixun
authors.initials: Z
authors.lastname: Shen
authors.affiliation: Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States.|Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Shoucheng
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology , Taipei 106, Taiwan (ROC).
authors.forename: Yingsheng
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Department of Physics, Department of Materials Science and Engineering, University of Washington , Seattle, Washington 98195, United States.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Xu
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Zahid
authors.initials: Z
authors.lastname: Hussain
authors.affiliation: Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States.|Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
authors.forename: Harold Y
authors.initials: HY
authors.lastname: Hwang
authors.affiliation: Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States.|Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.|Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Yi
authors.initials: Y
authors.lastname: Cui
authors.affiliation: School of Physical Science and Technology, ShanghaiTech University , Shanghai 200031, China.|CAS-Shanghai Science Research Center , 239 Zhang Heng Road, Shanghai 201203, China.|Physics Department, Clarendon Laboratory, University of Oxford , Parks Road, Oxford OX1 3PU, United Kingdom.|Diamond Light Source , Didcot, Oxfordshire OX11 0BW, United Kingdom.
authors.forename: Yulin
authors.initials: Y
authors.lastname: Chen
keywords: angle-resolved photoemission spectroscopy; band structure; transition metal dichalcogenides; valleytronics