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  1. Abstract

    Despite their great promise for providing a pathway for very efficient and fast manipulation of magnetization, spin‐orbit torque (SOT) operations are currently energy inefficient due to a low damping‐like SOT efficiency per unit current bias, and/or the very high resistivity of the spin Hall materials. This work reports an advantageous spin Hall material, Pd1−xPtx, which combines a low resistivity with a giant spin Hall effect as evidenced with three independent SOT ferromagnetic detectors. The optimal Pd0.25Pt0.75alloy has a giant internal spin Hall ratio of >0.60 (damping‐like SOT efficiency of ≈0.26 for all three ferromagnets) and a low resistivity of ≈57.5 µΩ cm at a 4 nm thickness. Moreover, it is found that the Dzyaloshinskii–Moriya interaction (DMI), the key ingredient for the manipulation of chiral spin arrangements (e.g., magnetic skyrmions and chiral domain walls), is considerably strong at the Pd1−xPtx/Fe0.6Co0.2B0.2interface when compared to that at Ta/Fe0.6Co0.2B0.2or W/Fe0.6Co0.2B0.2interfaces and can be tuned by a factor of 5 through control of the interfacial spin‐orbital coupling via the heavy metal composition. This work establishes a very effective spin current generator that combines a notably high energy efficiency with a very strong and tunable DMI for advanced chiral spintronics and spin torque applications.

  2. Abstract

    Magnetic skyrmions are topologically nontrivial chiral spin textures that have potential applications in next‐generation energy‐efficient and high‐density spintronic devices. In general, the chiral spins of skyrmions are stabilized by the noncollinear Dzyaloshinskii–Moriya interaction (DMI), originating from the inversion symmetry breaking combined with the strong spin–orbit coupling (SOC). Here, the strong SOC from topological insulators (TIs) is utilized to provide a large interfacial DMI in TI/ferrimagnet heterostructures at room temperature, resulting in small‐size (radius ≈ 100 nm) skyrmions in the adjacent ferrimagnet. Antiferromagnetically coupled skyrmion sublattices are observed in the ferrimagnet by element‐resolved scanning transmission X‐ray microscopy, showing the potential of a vanishing skyrmion Hall effect and ultrafast skyrmion dynamics. The line‐scan spin profile of the single skyrmion shows a Néel‐type domain wall structure and a 120 nm size of the 180° domain wall. This work demonstrates the sizable DMI and small skyrmions in TI‐based heterostructures with great promise for low‐energy spintronic devices.