Universal Spin Diffusion Length in Polycrystalline Graphene
Cummings, Aron (Institut Català de Nanociència i Nanotecnologia)
Dubois, Simon M. M. (Université Catholique de Louvain)
Charlier, Jean Christophe (Université Catholique de Louvain)
Roche, Stephan (Institut Català de Nanociència i Nanotecnologia)

Data:	2019
Resum:	Graphene grown by chemical vapor deposition (CVD) is the most promising material for industrial-scale applications based on graphene monolayers. It also holds promise for spintronics; despite being polycrystalline, spin transport in CVD graphene has been measured over lengths up to 30 μm, which is on par with the best measurements made in single-crystal graphene. These results suggest that grain boundaries (GBs) in CVD graphene, while impeding charge transport, may have little effect on spin transport. However, to date very little is known about the true impact of disordered networks of GBs on spin relaxation. Here, by using first-principles simulations, we derive an effective tight-binding model of graphene GBs in the presence of spin-orbit coupling (SOC), which we then use to evaluate spin transport in realistic morphologies of polycrystalline graphene. The spin diffusion length is found to be independent of the grain size, and it is determined only by the strength of the substrate-induced SOC. This result is consistent with the D'yakonov-Perel' mechanism of spin relaxation in the diffusive regime, but we find that it also holds in the presence of quantum interference. These results clarify the role played by GBs and demonstrate that the average grain size does not dictate the upper limit for spin transport in CVD-grown graphene, a result of fundamental importance for optimizing large-scale graphene-based spintronic devices.
Ajuts:	European Commission 785219 European Commission 696656 Ministerio de Economía y Competitividad SEV-2017-0706
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Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Graphene ; CVD ; Polycrystalline ; Grain boundaries ; Spin relaxation ; Spintronics
Publicat a:	Nano letters, Vol. 19, Issue 10 (October 2019) , p. 7418-7426, ISSN 1530-6992

DOI: 10.1021/acs.nanolett.9b03112
PMID: 31532994

Postprint 10 p, 3.9 MB

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