Spin-orbit and exchange proximity effects in 2d materials

DIPC Seminars

Jaroslav Fabian, University of Regensburg
Donostia International Physics Center
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Spin-orbit and exchange proximity effects in 2d materials Graphene and novel 2d materials offer new perspectives for spintronics [1]. However, graphene has no band gap, so its spintronic applications will be limited to being a highly efficient spin transfer channel. Heterostructures of graphene and two-dimensional transition-metal dichalcogenides (TMDC) are emerging as systems in which both orbital and spin properties can be controlled by gating, thus offering a materials basis for spintronic applications, such as bipolar spin devices. We have proposed that graphene on TMDCs can be used in optospintronics [2], since the direct gap of TMDCs allows optical spin orientation, with the successive transfer of spin into graphene. But these van der Waals stacks also yield interesting fundamental physics. We have recently shown that graphene on WSe2 exhibits an inverted band structure, which leads to helical edge states in graphene nanoribbons on WSe2 [3], with a bulk spin-orbit gap of about 1 meV, which is giant when compared to 24 micro eV in pristine graphene. I will also mention our most recent results the proximity effects in bilayer graphene as well as on engineering the proximity exchange in graphene and TMDCs in tunnel junctions with ferromagnetic metals [4]. 1. W. Han, R. Kawakami, M. Gmitra, and J. Fabian, Nature Nanotechnology 9, 794 (2014) 2. M. Gmitra and J. Fabian, Phys. Rev. B 92, 155403 (2015) 3. M. Gmitra, D. Kochan, P. Högl, and J. Fabian, Phys. Rev. B 93, 155104 (2016) 4. K. Zollner, M. Gmitra, T. Frank, and J. Fabian, Phys. Rev. B 94, 155441 (2016)