We report the observation of the intrinsic dampinglike spin-orbit torque (SOT) arising from the Berry curvature in metallic-magnet/CuO_{x} heterostructures. We show that a robust dampinglike SOT, an order of magnitude larger than a fieldlike SOT, is generated in the heterostructure despite the absence of the bulk spin-orbit effect in the CuO_{x} layer. Furthermore, by tuning the interfacial oxidation level, we demonstrate that the fieldlike SOT changes drastically and even switches its sign, which originates from oxygen-modulated spin-dependent disorder. These results provide important information for a fundamental understanding of the physics of the SOTs.

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This paper reports that a fine-tuning of orbital hybridization opens a door to atomic-level engineering of spin-orbit physics.

Oxide‐based memristor devices are being extensively studied as one of the most promising technologies for next generation nonvolatile memory and neuromorphic computing. However, the switching process of such devices relying on the formation and rupture of conductive filaments has not been easily controlled, and thus induces large cycle‐to‐cycle and device‐to‐device variations in resistive switching, which hinders the development of high‐performance memristors. High‐performance memristors that meet the requirements for truly electroforming‐free, highly uniform, and low‐power switching are yet to be developed. Here, a phase‐separated oxide memristor is demonstrated based on a spontaneous phase separation process to form amorphous TiO2 switching medium distributed among the crystalline CoO grains. The confinement of conductive filaments into the intergrain amorphous oxide phase effectively minimizes the stochasticity of filament formation and rupture, resulting in drastically enhanced switching uniformity. The designed microstructure also facilitates filament formation and dissolution during switching processes and leads to truly electroforming‐free switching and low switching power (simultaneous low switching voltage 0.4 V and low current 2.5 µA).

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Modern spintronics relies on the generation of spin currents through spin-orbit coupling. The spin-current generation has been believed to be triggered by current-induced orbital dynamics, which governs the angular momentum transfer from the lattice to the electrons in solids. The fundamental role of the orbital response in the angular momentum dynamics suggests the importance of the orbital counterpart of spin currents: orbital currents. However, evidence for its existence has been elusive. Here, we demonstrate the generation of giant orbital currents and uncover fundamental features of the orbital response. We experimentally and theoretically show that orbital currents propagate over longer distances than spin currents by more than an order of magnitude in a ferromagnet and nonmagnets. Furthermore, we find that the orbital current enables electric manipulation of magnetization with efficiencies significantly higher than the spin counterpart. These findings open the door to orbitronics that exploits orbital transport and spin-orbital coupled dynamics in solid-state devices.

We investigate the absorption of a spin current at a ferromagnetic-metal/Pt-oxide interface by measuring current-induced ferromagnetic resonance. The spin absorption was characterized by the magnetic damping of the heterostructure. We show that the magnetic damping of a Ni81Fe19 film is clearly enhanced by attaching Pt-oxide on the Ni81Fe19 film. The damping enhancement is disappeared by inserting an ultrathin Cu layer between the Ni81Fe19 and Pt-oxide layers. These results demonstrate an essential role of the direct contact between the Ni81Fe19 and Pt-oxide to induce sizable interface spin-orbit coupling. Furthermore, the spin-absorption parameter of the Ni81Fe19/Pt-oxide interface is comparable to that of intensively studied heterostructures with strong spin-orbit coupling, such as an oxide interface, topological insulators, metallic junctions with Rashba spin-orbit coupling. This result illustrates strong spin-orbit coupling at the ferromagnetic-metal/Ptoxide interface, providing an important piece of information for quantitative understanding the spin absorption and spin-charge conversion at the ferromagnetic-metal/metallic-oxide interface. * ando@appi.keio.ac.jp 1 A. Soumyanarayanan, N. Reyren, A. Fert, and C. Panagopoulos, Nature (London) 539, 509 (2016).