Spin-orbit proximity phenomena and tunable spin-to-charge interconversion in van der Waals heterostructures*

The isolation of a large variety of two-dimensional materials (2DM) and their co-integration in van der Waals heterostructures has opened new avenues for innovative material design and engineering. In particular, the structural interface quality in the atomically smooth 2DMs allows us to imprint properties of interest in a chosen 2DM by proximity-induced effects. Such an approach is particularly compelling for spintronic devices, which harness their functionality from thin layers of magnetic and non-magnetic materials and their interfaces. In this talk, I will present recent experiments in which we investigate the spin dynamics in graphene-transition metal dichalcogenides heterostructures. I will show that the spin-orbit coupling in graphene can be strongly enhanced by proximity effects. As a consequence, the spin relaxation becomes highly anisotropic, with spin lifetimes that are markedly different depending on the spin orientation [1,2]. I will further demonstrate that the proximity-induced spin-orbit coupling leads to strongly enhanced spin-to-charge interconversion [3]. By performing spin precession experiments in appropriately designed Hall bars, we are able to separate the contributions of the spin Hall and the spin galvanic effects. Remarkably, their corresponding conversion efficiencies can be tailored by electrostatic gating in magnitude and sign, peaking near the graphene charge neutrality point and having a large magnitude even at room temperature.
[1] L. A. Benítez et al., Nature Phys. 14 (2018)
[2] L. A. Benítez, et al., APL Materials 7, 120701 (2019)
[3] L. A. Benítez et al., Nature Mater. 19, 170 (2020)