title: Observation of monolayer valence band spin-orbit effect and induced quantum well states in MoX2.
abstract: Transition metal dichalcogenides [corrected] have attracted much attention recently due to their potential applications in spintronics and photonics because of the indirect to direct band gap transition and the emergence of the spin-valley coupling phenomenon upon moving from the bulk to monolayer limit. Here, we report high-resolution angle-resolved photoemission spectroscopy on MoSe2 single crystals and monolayer films of MoS2 grown on highly ordered pyrolytic graphite substrate. Our experimental results resolve the Fermi surface trigonal warping of bulk MoSe2, and provide evidence for the critically important spin-orbit split valence bands of monolayer MoS2. Moreover, we systematically image the formation of quantum well states on the surfaces of these materials, and present a theoretical model to account for these experimental observations. Our findings provide important insights into future applications of transition metal dichalcogenides in nanoelectronics, spintronics and photonics devices as they critically depend on the spin-orbit physics of these materials.
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Nasser
authors.initials: N
authors.lastname: Alidoust
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Guang
authors.initials: G
authors.lastname: Bian
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Su-Yang
authors.initials: SY
authors.lastname: Xu
authors.affiliation: Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Raman
authors.initials: R
authors.lastname: Sankar
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Madhab
authors.initials: M
authors.lastname: Neupane
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Ilya
authors.initials: I
authors.lastname: Belopolski
authors.affiliation: Condensed Matter and Materials Division, Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: Dong-Xia
authors.initials: DX
authors.lastname: Qu
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94305, USA.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Denlinger
authors.affiliation: Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Fang-Cheng
authors.initials: FC
authors.lastname: Chou
authors.affiliation: Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: M Zahid
authors.initials: MZ
authors.lastname: Hasan