Optical and electronic properties of 2H−MoS₂ under pressure : revealing the spin-polarized nature of bulk electronic bands
Brotons Gisbert, Mauro (Universitat de València. Departament de Física Aplicada i Electromagnetisme)
Segura, Alfredo (Universitat de València. Departament de Física Aplicada i Electromagnetisme)
Robles, Roberto (Institut Català de Nanociència i Nanotecnologia)
Canadell Casanova, Enric 1950- (Institut de Ciència de Materials de Barcelona)
Ordejon, Pablo (Institut Català de Nanociència i Nanotecnologia)
Sánchez Royo, Juan F. (Universitat de València. Departament de Física Aplicada i Electromagnetisme)

Date:	2018
Abstract:	Monolayers of transition-metal dichalcogenide semiconductors present spin-valley locked electronic bands, a property with applications in valleytronics and spintronics that is usually believed to be absent in their centrosymmetric (as the bilayer or bulk) counterparts. Here we show that bulk 2H−MoS₂ hides a spin-polarized nature of states determining its direct band gap, with the spin sequence of valence and conduction bands expected for its single layer. This relevant finding is attained by investigating the behavior of the binding energy of A and B excitons under high pressure, by means of absorption measurements and density-functional-theory calculations. These results raise an unusual situation in which bright and dark exciton degeneracy is naturally broken in a centrosymmetric material. Additionally, the phonon-assisted scattering process of excitons has been studied by analyzing the pressure dependence of the linewidth of discrete excitons observed at the absorption coefficient edge of 2H−MoS₂. Also, the pressure dependence of the indirect optical transitions of bulk 2H−MoS2 has been analyzed by absorption measurements and density-functional-theory calculations. These results reflect a progressive closure of the indirect band gap as pressure increases, indicating that metallization of bulk MoS₂ may occur at pressures higher than 26 GPa.
Grants:	European Commission 676598 Ministerio de Economía y Competitividad FIS2015-64886-C5-4-P Ministerio de Economía y Competitividad FIS2015-64886-C5-3-P Ministerio de Economía y Competitividad SEV-2015-0496 Ministerio de Economía y Competitividad TEC2014-53727-C2-1-R Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-1506
Rights:	Tots els drets reservats.
Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Published in:	Physical review materials, Vol. 2, issue 5 (May 2018) , art. 54602, ISSN 2475-9953

DOI: 10.1103/PhysRevMaterials.2.054602

Post-print 36 p, 2.4 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Catalan Institute of Nanoscience and Nanotechnology (ICN2)
Articles > Research articles
Articles > Published articles