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Interfacially asymmetric magnetic multilayers made of heavy metal/ferromagnet have attracted considerable attention in the spintronics community for accommodating spin-orbit torques (SOTs) and meanwhile for hosting chiral spin textures. In these multilayers, the accompanied interfacial Dzyaloshinskii–Moriya interaction (iDMI) permits the formation of Néel-type spin textures. While significant progresses have been made in Co, CoFeB, Co2FeAl, CoFeGd based multilayers, it would be intriguing to identify new magnetic multilayers that could enable spin-torque controllability and meanwhile host nanoscale skyrmions. In this report, first, thin films made of permanent magnet SmCo5 with perpendicular magnetic anisotropy are synthesized, in which the deterministic SOT switching, enabled by the spin Hall effect, in Pt/SmCo5/Ta trilayer is demonstrated. Further, the stabilization of room-temperature skyrmions with diameters ≈100 nm in [Pt/SmCo5/Ta]15, together with a skyrmionium-like spin texture in [Pt/SmCo5/Ir]15 multilayers is shown. Based on the material specific parameters, micromagnetic simulations are also carried out. The results confirm the presence of chiral spin textures in this new material family. Through interfacial engineering, the results thus demonstrate that rare earth permanent magnets could be a new platform for studying interfacial chiral spintronics.

Néel skyrmions are generally realized in asymmetric multilayers made of heavy metals (HMs) and ultrathin ferromagnets possessing strong interfacial Dzyaloshinskii-Moriya interactions (iDMIs). Depending on the relative strengths of iDMIs at the interfaces, various types of Néel skyrmions have been suggested, which are typified with characteristically different topological properties and current-driven dynamics. This suggests the importance of a precise quantification of their spin chiralities. In this paper, we explore the possibility of realizing Néel skyrmions in magnetic multilayers without the direct usage of standard HMs. Specifically, through depositing a thin layer of ferrimagnetic (FIM) CoTb layer on top of an antiferromagnetic (AFM) quantum material of composition Mn3Sn, the AFM exchange interaction at the asymmetric interface provides an equivalent iDMI for stabilizing FIM Néel skyrmions. Secondly, through using advanced four-dimensional Lorentz scanning transmission electron microscopy (4D LSTEM), in combination with x-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM), we can directly determine the spin chirality of FIM Néel skyrmions. The present findings not only broaden the phase space for chiral interfacial magnetism but also provide a possibility for future applications of heavy-metal-free skyrmionic devices.

The efficient generation, manipulation and detection of magnetic skyrmions are important for the development of future spintronic devices. One approach is to use electric-current-induced spin torques. Recently, thermally induced skyrmion motion has also been observed, but wider experimental evidence and its capabilities remain limited. Here we report the thermal generation, manipulation and thermoelectric detection of nanoscale skyrmions in microstructured metallic multilayers integrated with on-chip heaters. The local application of heat can facilitate a domain morphological transition and the formation of skyrmions at the device edge, where a low energy barrier exists. We observe the unidirectional diffusion of skyrmions from hot regions to cold regions, which is due to the interplay among the repulsive forces between skyrmions, thermal spin–orbit torques, entropic forces and magnonic spin torques. The thermally generated skyrmions can also be electrically detected via the Nernst voltage.

Toward low-energy-consumption spintronic devices, magnetic multilayers that host chiral spin textures, as well as efficient spin-torques, are highly promising. As compared with resistive materials, superconducting materials are optimal for constructing dissipationless electronic devices, in which the electricity is conducted without producing Joule heating. In this regard, magnetic multilayers containing superconductors are well suited for building ultra-low power spintronic devices. Following this motivation, we study the possible existence of chiral spin textures in the two-dimensional (2D) high temperature superconductor/ferrimagnet heterostructures of stacking order Bi2Sr2CaCu2O8+δ/Fe1−xTbx and stacking order Bi2Sr2CaCu2O8+δ/Co1−xTbx. Through x-ray photon-emission electron microscopy, we observe bubble-like spin textures in a wide temperature range. Based on the first-principles calculations, the important role of spin–orbit interaction from the BiO termination layer is discussed, which induces a very large interfacial Dzyaloshinskii–Moriya interaction and results in the possible existence of chiral spin textures on top of superconductors. Our work suggests that the layered high-temperature superconductor could be incorporated for stabilizing chiral spin textures and for building dissipationless spin-orbitronic devices. [ABSTRACT FROM AUTHOR]

Spectral data of the outer wall and inner capsule of Pericarpium Citri Reticulatae Viride from different regions (Anhui, Guangdong, and Sichuan) were collected with portable near infrared spectrometer. Multiple interferences in the spectra were eliminated using single and combined pretreatment methods. Pattern recognition methods such as principal component analysis (PCA), cluster independent soft pattern classification (SIMCA) and Fisher linear discriminant analysis (FLDA) were used to establish traceability models of Pericarpium Citri Reticulatae Viride origin. The results showed that spectral pretreatment could eliminate the interferences of baseline drift, background, and spectral peak overlap to a certain extent. However, the traceability analysis of the origin couldn't be achieved. Among the three pattern recognition methods, accurate traceability analysis of Pericarpium Citri Reticulatae Virid couldn't be achieved with PCA method. The whole identification rate of SIMCA model with the outer wall and inner capsule original spectra were 99.14% and 98.28%, respectively. The whole identification rates of FLDA models were both 99.57%, better than that of SIMCA models. The identification rates of SIMCA and FLDA models with appropriate spectral pretreatment were 100%. Therefore, portable near infrared spectroscopy technology combined with the supervised pattern recognition methods can achieve non-destructive traceability analysis of Pericarpium Citri Reticulatae Viride origin, expanding a new way for the traceability analysis of food and drug homologous substances origin. [ABSTRACT FROM AUTHOR]

Electrical switching of topological antiferromagnetic states in Mn3Sn thin films has been a subject of active investigation. However, dependences of switching behaviors on the film thickness, external field, and crystal orientation remain to be fully explored, which motivate the present study. In this work, (11 2 ̄ 0) -orientated Mn3Sn thin films are fabricated on sapphire substrates, in which a large anomalous Hall effect over a wide temperature range (270–400 K) can be identified. The current-induced spin–orbit torques (SOTs) are utilized to electrically manipulate the topological antiferromagnetic states in Mn3Sn/Pt bilayers. The robust SOT switching can be realized in Mn3Sn films with thicknesses up to 100 nm and with in-plane fields up to 1200 mT. Furthermore, SOT switching behaviors that are independent of the choice of crystal orientations are clearly revealed. Our results could be useful for implementing Mn3Sn films for efficient and stable antiferromagnetic spintronics. [ABSTRACT FROM AUTHOR]

In this paper, the growth of rare‐earth‐free compensated ferrimagnet (C‐FIM) Mn4N single crystalline films is reported, with perpendicular magnetic anisotropy (PMA) on the MgO(001) substrates by reactive magnetron sputtering. Subsequently, the current‐induced spin‐orbit torque (SOT) switching is experimentally demonstrated through passing currents in the Hall bar device made of Mn4N/Pt bilayer, with the thickness of Mn4N approaching 60 nm. Furthermore, the accompanied SOT efficiencies are characterized by employing the harmonic Hall voltage measurements. In particular, an enhanced effective SOT efficiency with the increased thickness of Mn4N films is observed, suggesting the existence of a bulk‐like spin torque in the present material system. The results demonstrate that the perpendicularly magnetized C‐FIM Mn4N films can provide a promising material platform for developing the rare‐earth‐free FIM spintronics devices. [ABSTRACT FROM AUTHOR]

Interfacially asymmetric magnetic multilayers made of heavy metal/ferromagnet have attracted considerable attention in the spintronics community for accommodating spin‐orbit torques (SOTs) and meanwhile for hosting chiral spin textures. In these multilayers, the accompanied interfacial Dzyaloshinskii–Moriya interaction (iDMI) permits the formation of Néel‐type spin textures. While significant progresses have been made in Co, CoFeB, Co2FeAl, CoFeGd based multilayers, it would be intriguing to identify new magnetic multilayers that could enable spin‐torque controllability and meanwhile host nanoscale skyrmions. In this report, first, thin films made of permanent magnet SmCo5 with perpendicular magnetic anisotropy are synthesized, in which the deterministic SOT switching, enabled by the spin Hall effect, in Pt/SmCo5/Ta trilayer is demonstrated. Further, the stabilization of room‐temperature skyrmions with diameters ≈100 nm in [Pt/SmCo5/Ta]15, together with a skyrmionium‐like spin texture in [Pt/SmCo5/Ir]15 multilayers is shown. Based on the material specific parameters, micromagnetic simulations are also carried out. The results confirm the presence of chiral spin textures in this new material family. Through interfacial engineering, the results thus demonstrate that rare earth permanent magnets could be a new platform for studying interfacial chiral spintronics. [ABSTRACT FROM AUTHOR]

The explosive demands of storage capacity and the von Neumann bottleneck of modern computer architectures trigger many innovations in information technology. Amongst them, nonvolatile spintronics attract considerable attentions for which can embed the computation capability into memory, enable neuromorphic, and probabilistic computing. These exciting progresses typically rely on the manipulation of the relative magnetization orientations of two magnetic layers. By extending to 3D spintronic architectures made of multiple magnetic layers (n), the exponentially increased 2n magnetic states can provide ample opportunities for implementing novel spintronic functionalities. Here, through building perpendicularly magnetized 3D spin‐orbitronic architectures – [Pt/Fe1−xTbx/Si3N4]n multilayers, it is demonstrated the electrical programing of 2n memory states via current‐induced spin–orbit torques (SOTs), and the accompanied reconfigurable multifunction in‐memory logic features in a single four‐terminal Hall device. Further, an electrical readout of these 2n states, together with the implementation of Boolean logic gates and digital circuitry such as 2–4 and 3–8 decoders, are successfully conducted. More complex logic circuits are also envisioned. The experiments thus substantiate 3D spin‐orbitronic structures as a promising platform for exponentially boosting the storage capacity and accommodating in‐memory computing that can be important for promoting the emerging 3D nanospintronics. [ABSTRACT FROM AUTHOR]