Jose H. Garcia, Marc Vila, Chuang-Han Hsu, Stephan Roche, Vitor M. Pereira, Xavier Waintal, Fundación 'la Caixa', National University of Singapore, Agence Nationale de la Recherche (France), European Commission, Generalitat de Catalunya, Agencia Estatal de Investigación (España), Ministerio de Ciencia, Innovación y Universidades (España), National Research Foundation Singapore, ICN2 - Institut Catala de Nanociencia i Nanotecnologia (ICN2), Universitat Autònoma de Barcelona (UAB), National University of Singapore (NUS), Laboratory of Quantum Theory (GT), PHotonique, ELectronique et Ingénierie QuantiqueS (PHELIQS), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)
We report an unconventional quantum spin Hall phase in the monolayer WTe2, which exhibits hitherto unknown features in other topological materials. The low symmetry of the structure induces a canted spin texture in the yz plane, which dictates the spin polarization of topologically protected boundary states. Additionally, the spin Hall conductivity gets quantized (2e2/h) with a spin quantization axis parallel to the canting direction. These findings are based on large-scale quantum simulations of the spin Hall conductivity tensor and nonlocal resistances in multiprobe geometries using a realistic tight-binding model elaborated from first-principle methods. The observation of this canted quantum spin Hall effect, related to the formation of topological edge states with nontrivial spin polarization, demands for specific experimental design and suggests interesting alternatives for manipulating spin information in topological materials., M. V. acknowledges support from “La Caixa” Foundation and the Centre for Advanced 2D Materials at the National University of Singapore for its hospitality. X. W. acknowledges the ANR Flagera GRANSPORT funding. ICN2 authors were supported by the European Union Horizon 2020 research and innovation programme under Grant Agreement No. 881603 (Graphene Flagship) and No. 824140 (TOCHA, H2020-FETPROACT-01-2018). ICN2 is funded by the CERCA Programme/Generalitat de Catalunya, and is supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV2017-0706). V. M. P. acknowledges the support of the National Research Foundation (Singapore) under its Medium-Sized Centre Programme (R-723-000-001-281).