Low-symmetry topological materials for large charge-to-spin interconversion : the case of transition metal dichalcogenide monolayers
Vila Tusell, Marc (Universitat Autònoma de Barcelona. Departament de Física)
Hsu, Chuang-Han (National University of Singapore. Department of Electrical and Computer Engineering)
Garcia, José H. (Institut Català de Nanociència i Nanotecnologia)
Benítez, L. Antonio (Institut Català de Nanociència i Nanotecnologia)
Waintal, Xavier (Université Grenoble Alpes. Commissariat à l'énergie atomique et aux énergies alternatives)
Valenzuela, Sergio O. (Institut Català de Nanociència i Nanotecnologia)
Pereira, Víctor M. (National University of Singapore. Centre for Advanced 2D Materials and Graphene Research Centre)
Roche, Stephan (Institut Català de Nanociència i Nanotecnologia)

Data:	2021
Resum:	The spin polarization induced by the spin Hall effect (SHE) in thin films typically points out of the plane. This is rooted on the specific symmetries of traditionally studied systems, not in a fundamental constraint. Recently, experiments on few-layer MoTe2 and WTe2 showed that the reduced symmetry of these strong spin-orbit coupling materials enables a new form of canted spin Hall effect, characterized by concurrent in-plane and out-of-plane spin polarizations. Here, through quantum transport calculations on realistic device geometries, including disorder, we predict a very large gate-tunable SHE figure of merit λsθxy≈1-50 nm in MoTe2 and WTe2 monolayers that significantly exceeds values of conventional SHE materials. This stems from a concurrent long spin diffusion length (λs) and charge-to-spin interconversion efficiency as large as θxy≈80%, originating from momentum-invariant (persistent) spin textures together with large spin Berry curvature along the Fermi contour, respectively. Generalization to other materials and specific guidelines for unambiguous experimental confirmation are proposed, paving the way toward exploiting such phenomena in spintronic devices. These findings vividly emphasize how crystal symmetry and electronic topology can govern the intrinsic SHE and spin relaxation, and how they may be exploited to broaden the range and efficiency of spintronic materials and functionalities.
Ajuts:	European Commission 881603 European Commission 824140 Ministerio de Ciencia e Innovación SEV-2017-0706 Agencia Estatal de Investigación PID2019-111773RB-I00
Nota:	Altres ajuts: M.V. acknowledges support from "La Caixa" Foundation. ICN2 is funded by the CERCA Programme/Generalitat de Catalunya.
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Coupling materials ; Fundamental constraints ; Interconversions ; New forms ; Out-of-plane ; Spin-orbit couplings ; Spin-polarization ; Thin-films ; Topological materials ; Transition metal dichalcogenides (TMD)
Publicat a:	Physical Review Research, Vol. 3, issue 4 (Dec. 2021) , art. 43230, ISSN 2643-1564

DOI: 10.1103/PhysRevResearch.3.043230

9 p, 750.9 KB

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