Spin-charge conversion in 2D semimetals

As an all-electrical scheme to generate, detect and manipulate spin current, the spin Hall effect has been heavily investigated as a primary route toward next-generation spintronic devices. Traditional spin Hall materials are mostly based on heavy metals, like Pt, W and Ta, that have strong spin-orbit coupling. However, the high symmetry and dimensionality of these materials make the control and optimization of spin Hall effect a major obstacle toward device applications.¹ Low-symmetry 2D semimetals have been emerging materials to study novel spin Hall effects and their control.² In this talk, I will present our recent progress in this regard to generate and control novel spin-charge conversion in 2D semimetals. Through transport studies, we observed a novel spin Hall effect that can generate out-of-plane spin polarization due to symmetry breaking. Furthermore, using 2D semimetal as a spin Hall layer, we achieved electrostatic control of spin-charge conversion in a broad range, which is extremely difficult for heavy metals. Finally, I will discuss how we use van der Waals heterostructures of 2D semimetal and 2D ferromagnets to achieve highly efficient interface spin transport and eventually a spin readout signal that is two orders of magnitudes higher than conventional 3D structures. Our demonstrations prove the appealing potential of 2D spin Hall crystals as building block for highly efficient spintronic devices, including memory and logic devices.



References

[1] Sinova, J.; Valenzuela, S. O.; Wunderlich, J.; Back, C. H.; Jungwirth, T., Rev. Mod. Phys. 2015, 87, 1213-1260.

[2] Song, P.; Hsu, C.-H. et al, Nat. Mater. 2020, 19, 292-298.