Spin current effects in 2D magnets/heavy metal bilayers

Jing Shi

2D van der Waals (vdW) magnetic materials offer exciting new opportunities to study interfacial phenomena arising from or enhanced by the atomically flat interfaces. I will present our recent studies on three types of bilayer systems composed of vdW magnet and Pt: Cr₂Ge₂Te₆/Pt, Fe₃GeTe₂/Pt, and Pt/CI₃.  In each bilayer, the exfoliated vdW magnet consists of 10’s atomic layer units and the sputtered 5 nm Pt layer is either below or above the vdW magnet. In Cr₂Ge₂Te₆/Pt and Pt/CI₃, both Cr₂Ge₂Te₆ and CI₃ are insulating, we use induced magneto-transport properties in Pt to probe the spin states and magnetic domains in the insulating magnets [1-3]. Unlike these two insulating magnets, Fe₃GeTe₂ is a metallic ferromagnet which has the highest Curie temperature among all 2D vdW magnets, strong perpendicular magnetic anisotropy, and more resistive than Pt; therefore, it is an excellent 2D magnet for investigating the spin-orbit torque effects. We demonstrate that Fe₃GeTe₂/Pt has a spin-orbit torque efficiency comparable with that in the best bilayers made with 3D magnets and the Fe₃GeTe₂ magnetization can be switched with a relatively low critical current density [4]. These excellent properties show great potential of 2D materials for spintronic applications.

1. B. Niu, T. Su, et al., Nano Lett. 20, 553 (2020). DOI: 10.1021/acs.nanolett.9b04282.
2. M. Lohmann, et al., Nano Lett. 19, 2397 (2019). DOI: 10.1021/acs.nanolett.8b05121.
3. T. Su, et al., 2D Materials 7, 045006 (2020). DOI:10.1088/2053-1583/ab9dd5.
4. M. Alghamdi, M. Lohmann, et al., Nano Lett. 19, 4400 (2019). DOI: 10.1021/acs.nanolett.9b01043.