title: Intervalley scattering by acoustic phonons in two-dimensional MoS2revealed by double-resonance Raman spectroscopy.
abstract: Double-resonance Raman scattering is a sensitive probe to study the electron-phonon scattering pathways in crystals. For semiconducting two-dimensional transition-metal dichalcogenides, the double-resonance Raman process involves different valleys and phonons in the Brillouin zone, and it has not yet been fully understood. Here we present a multiple energy excitation Raman study in conjunction with density functional theory calculations that unveil the double-resonance Raman scattering process in monolayer and bulk MoS2. Results show that the frequency of some Raman features shifts when changing the excitation energy, and first-principle simulations confirm that such bands arise from distinct acoustic phonons, connecting different valley states. The double-resonance Raman process is affected by the indirect-to-direct bandgap transition, and a comparison of results in monolayer and bulk allows the assignment of each Raman feature near the M or K points of the Brillouin zone. Our work highlights the underlying physics of intervalley scattering of electrons by acoustic phonons, which is essential for valley depolarization in MoS2.
authors.affiliation: Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil.
authors.forename: Bruno R
authors.initials: BR
authors.lastname: Carvalho
authors.affiliation: Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, State College, Pennsylvania 16802, USA.
authors.forename: Yuanxi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK.|Department of Physics, King's College London, Strand, London WC2R 2LS, UK.
authors.forename: Sandro
authors.initials: S
authors.lastname: Mignuzzi
authors.affiliation: National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK.|Department of Physics, King's College London, Strand, London WC2R 2LS, UK.
authors.forename: Debdulal
authors.initials: D
authors.lastname: Roy
authors.affiliation: Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, State College, Pennsylvania 16802, USA.|Department of Chemistry, The Pennsylvania State University, University Park, State College, Pennsylvania 16802, USA.|Department of Materials Science and Engineering, The Pennsylvania State University, University Park, State College, Pennsylvania 16802, USA.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Terrones
authors.affiliation: Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil.
authors.forename: Cristiano
authors.initials: C
authors.lastname: Fantini
authors.affiliation: Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, State College, Pennsylvania 16802, USA.
authors.forename: Vincent H
authors.initials: VH
authors.lastname: Crespi
authors.affiliation: Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil.
authors.forename: Leandro M
authors.initials: LM
authors.lastname: Malard
authors.affiliation: Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 30123-970, Brazil.
authors.forename: Marcos A
authors.initials: MA
authors.lastname: Pimenta