Spin in 2D Electronics

Saroj Dash, Chalmers University of Technology

June 30, 2020

Engineering 2D materials heterostructures by combining the best of different layers in one ultimate unit can offer a plethora of opportunities in condensed matter physics. Here, we demonstrated electronic creation, transport, and control of spin polarization in 2D materials heterostructures at room temperature. While large-area CVD graphene is shown to be an excellent medium for long-distance spin communication and fabrication of spin circuits [1,2], the insulating CVD h-BN has shown a substantial tunnel spin polarization up to 65% [3]. Furthermore, by inducing spin-orbit coupling and spin absorption effects, we demonstrated an electrical gate control of spin-polarization and spin lifetime in graphene/MoS2 heterostructures [4].

The induction of proximity induced spin-orbit coupling and magnetic exchange interactions in graphene can provide a new electronic state of mater. Recently, we combined graphene with topological insulators  in van der Waals heterostructures to demonstrate the emergence of a strong proximity-induced spin-orbit coupling in graphene [5], consequently giving rise to a giant and gate-tunable spin galvanic effects at room temperature [6]. Using graphene in heterostructure with a layered magnetic insulator CrGeTe, we also demonstrated proximity induced magnetic exchange interaction in graphene [7].

The electrical creation of spin polarization in topological materials is promising for applications in spin-orbit and quantum technologies. By utilizing the electronic band structures of the topological Weyl semimetals and Rashba spin-orbit materials, we demonstrated significant charge-spin conversion effects up to room temperature. We reported a substantial charge-spin conversion effect in Weyl semimetal candidate WTe2 [8,9] and Rashba material BiTeBr [10], and show its application for spin injection into graphene at room temperature. These findings demonstrate all-electrical spintronic devices at room temperature in van der Waals heterostructure, which can be essential building blocks in future device architectures.

[1] Nature Communications 6, 6766 (2015).
[2] Carbon 161, 892-899 (2020).
[3] Scientific Reports 6, 21168 (2016).
[4] Nature Communications 8, 16093 (2017).
[5] Science Advances 4:eaat9349 (2018).
[6] arXiv:1910.06760 (2019).
[7] 2D Materials 7 015026 (2020).
[8] Physical Review Research 2 (1), 013286 (2020).
[9] arXiv:1910.06225 (2019).
[10] Nano Letter (2020). https://doi.org/10.1021/acs.nanolett.0c00458.