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Abstract |
In this talk, I will present theoretical spin transport features in Quantum Materials such as MoTe2 and WTe2-based materials which have recently been the subject of great attention within the broad context of Topological Quantum Matter [1]. By focusing on the monolayer limit, using DFT-derived tight-binding models and using both efficient bulk and multi-terminal formalisms and techniques [2,3], I will first discuss the emergence of new forms of intrinsic spin Hall effect (SHE) that produce large and robust in-plane spin polarizations. Quantum transport calculations on realistic device geometries with disorder demonstrate large charge-to-spin interconversion efficiency with gate tunable spin Hall angle as large as θxy≈80%, and SHE figure of merit λs.θxy∼8-10 nm, largely superior to any known SHE material [4]. Besides, I will present our theoretical prediction of an unconventional canted quantum spin Hall phase in the monolayer Td-WTe2, which exhibits hitherto unknown features in other topological materials [5]. The low-symmetry of the structure induces a canted spin texture in the yz plane, dictating 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. Our theoretical predictions for the canted QSHE findings have just been confirmed experimentally [6], and we have also shown that a perpendicular electric field could tailor the canting angle, with a 90° coherent rotation [7]. I will finally discuss the role of entanglement between intraparticle degrees of freedom in spin transport and dynamical patterns of entanglement, as enabling novel platform for generating and manipulating quantum entanglement between internal and interparticle degrees of freedom [8].
[1] The 2020 Quantum Materials Roadmap, F. Giustino et al., J. Phys. Mater. 3 042006 (2020); [2] M. Vila et al., Phys. Rev. Lett. 124, 196602 (2020); [3] Z. Fan et al., Physics Reports 903, 1-69 (2021); [4] M. Vila et al., Phys. Rev. Research 3, 043230 (2021); [5] J.H. Garcia et al., Phys. Rev. Lett. 125 (25), 256603 (2020); [6] W. Zhao et al., Phys. Rev. X 11, 041034 (2021); [7] J.H. Garcia et al., submitted Phys Rev Lett.; [8] BG de Moraes et al., Physical Review B 102 (4), 041403 (2020). |
