Spin Transport in 2D Materials and Topological Matter – Prof. Stephan Roche, Catalan Institute of Nanoscience and Nanotechnology

October 17, 2019 @ 2:15 pm – 3:15 pm
TCM Seminar Room
Cavendish Laboratory
Bartomeu Monserrat

The physics of graphene can be strongly enriched and manipulated by harvesting the large amount of possibilities of proximity effects with magnetic insulators (including 2D magnetic layers) and strong SOC materials (TMDC, topological insulators, etc). Simultaneously, the presence of extra degrees of freedom (sublattice pseudospin, valley isospin) points towards new directions for information processing [1,2], extending the playground to valleytronics, multifunctional electronic devices or novel quantum computing paradigms harnessing all these degrees of freedom in combination with electromagnetic fields or other external fields (strain, chemical functionalization) [3,4].

Here I will present some foundations of spin transport for Dirac fermions propagating in supported graphene devices or interfaced with strong SOC materials. The role of entanglement with “valley and sublattice pseudospins” in tailoring the spin dephasing and relaxation mechanisms will be explained as well as the impact of strong SOC proximity effects on spin lifetime anisotropy, weak antilocalization and Spin Hall effect [4-7]. Recent results showing universal spin difussion length in polycrystalline Graphene and nonlocal resistance transprot phenomena in the crossover from ballistic to diffusive regimes will be also introduced [8]

[1] S. Roche et al. 2D Materials 2, 030202 (2015)
[2] D.V. Tuan et al. Nature Physics 10, 857 (2014)
[3] D.V. Tuan & S. Roche, Phys. Rev. Lett 116, 106601 (2016)
[4] A.W. Cummings, J. H. García, J. Fabian and S. Roche, Phys. Rev. Lett. 119, 206601 (2016)
[5] J.H. García, A.W. Cummings, S. Roche, Nano Lett. 17 (8), 5078–5083 (2017).
[6] K. Song et al. Nano letters 18 (3), 2033 (2018)
[7] J.H. García et al. Chem Soc. Rev 47, 3359-3379 (2018); CK Safeer, J Ingla-Aynés, F Herling, JH Garcia, M Vila, N Ontoso, et al. Nano letters 19 (2), 1074-1082 (2019); L. Benitez, W. Torres, J. Sierra, M. Timmermans, J. Garcia, S. Roche, et al. arXiv:1908.07868 (submitted to Nature Materials)
[8] A.W. Cummings, SMM Dubois, J.C. Charlier, S. Roche, arXiv:1907.12761 (Nano Letters, 10.1021/acs.nanolett.9b03112); M. Vila, J. Garcia, A.W. Cummings, C. Groth, X. Waintal and S. Roche (submitted to Phys. Rev. Lett.)