Recent advances in two-dimensional van der Waals (2D vdW) magnet provide new platforms to study the magnetism in reduced dimensions. However, most of the studies performed to date have been...

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Spin-orbit torque (SOT) provides an efficient approach to control the magnetic state and dynamics in different classes of materials. Recent years, the crossover between two-dimensional van der Waals (2D vdW) materials and SOT opens a new prospect to push SOT devices to the 2D limit. In this mini-review, we summarize the latest progress in 2D vdW materials for SOT applications, highlighting the comparison of the performance between devices with various structures. It is prospected that the large family of 2D vdW materials and numerous combinations of heterostructures will widely extend the material choices and bring new opportunities to SOT devices in the future.

Spin orbit torques (SOTs) in ferromagnet/heavy-metal heterostructures have provided great opportunities for efficient manipulation of spintronic devices. However, deterministically field-free switching of perpendicular magnetization with SOTs is forbidden because of the global two-fold rotational symmetry in conventional heavy-metal such as Pt. Here, we engineer the interface of Pt/Ni heterostructures by inserting a monolayer MoTe2 with low crystal symmetry. It is demonstrated that the spin orbit efficiency, as well as the out-of-plane magnetic anisotropy and the Gilbert damping of Ni are enhanced, due to the effect of orbital hybridization and the increased spin scatting at the interface induced by MoTe2. Particularly, an out-of-plane damping-like torque is observed when the current is applied perpendicular to the mirror plane of the MoTe2 crystal, which is attributed to the interfacial inversion symmetry breaking of the system. Our work provides an effective route for engineering the SOT in Pt-based heterostructures, and offers potential opportunities for van der Waals interfaces in spintronic devices.

Spin mixing conductance (SMC) at the ferromagnetic/non-magnetic material (FM/NM) interface governs the transport efficiency of the spin current. A high level of SMC is crucial for efficient spin injection and spin manipulation. Here, we report a reliable way to enhance the SMC at the FM/NM interface by rare-earth doping in the NM layer. As evidenced by the decreased saturation magnetization in permalloy (Py)/Cu–Nd structures, an induced magnetism in Nd is proposed, which is likely to be antiferromagnetically coupled to Py at the interface. By changing the doping content of Nd, the Py/Cu–Nd interface can be well designed, which gives rise to an effective tuning of the SMC from 0.37 × 1015 to 16.26 × 1015 cm−2. Such a tuning effect of SMC is suppressed by inserting a Cu spacer, demonstrating the key role of the antiferromagnetically coupled interface to the improved SMC. Our results highlight the significance of rare-earth materials in spin transport, expanding the design capability of energy-efficient spintronic devices.

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In recent years, two-dimensional van der Waals (2D-vdW) magnets have been widely employed in spintronic devices since they can be reduced to the monolayer while maintaining structural integrity. In this paper, an interfacial effect of the heterostructure including the Co 60 Fe 20 B 20 (CFB) layer and Fe 3 GeTe 2 (FGT) flake is explored. At the Curie temperature (T c ) of FGT, a reduction in the magnetization of the CFB/FGT bilayer is found compared to that of CFB itself unlike at 300 K. It is possible that non-parallel magnetic moments are formed at the interface due to the strong perpendicular magnetic anisotropy (PMA) of magnetic FGT below T c . Using a ferromagnetic resonance technique, we find that both PMA and the magnetic damping of CFB are enhanced by the FGT interface. Particularly, the PMA constant K ⊥ is increased by 20.2% at 300 K, much larger than that at 150 K, which indicates that the enhancement of PMA is induced by orbital hybridization at the interface instead of the magnetic proximity effect. The exchange interaction at the interface for moments between CFB and FGT may play a minor role in the enhancement of PMA of CFB induced by FGT. Also, such a less PMA enhancement at 150 K may be blocked by the magnetic interface of FGT below T c . This research highlights that the magnetism of CFB can be modulated by the interface of FGT even at room temperature, which provides a new approach for the application of 2D-vdW magnets in spintronics.