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Spin–orbit torques (SOTs) provide an efficient way to electrically manipulate the magnetic order in spintronic devices. Compared with conventional ferromagnetic materials, ferrimagnetic materials have the advantages of antiferromagnetically coupled sublattices and induced ultrafast spin dynamics. In this paper, we study the current-induced magnetization switching in the ferrimagnetic Ta/GdFeCo/MgO system. Robust SOT-induced magnetization switching can be achieved at the magnetic compensation temperature point of around 70 K, where the magnetization is nearly zero and the coercivity can reach almost 3 T. The temperature dependence of the SOT efficiency is quantified by the second harmonic method, and the enhanced SOT efficiency near the magnetic compensation temperature is attributed to the negative exchange coupling between the two sublattices of CoFe and Gd. This work demonstrates the SOT switching of the nearly compensated ferrimagnet, with great potential for future magnetic interaction-free and ultrafast ferrimagnetic applications.

All 16 Boolean logic functions in a single Ta/CoFeB/MgO device with perpendicular magnetic anisotropy were experimentally demonstrated based on the spin–orbit torque (SOT) effect. Furthermore, by combining with the voltage-controlled magnetic anisotropy (VCMA) effect, a novel SOT-MTJ (magnetic tunnel junction) prototype device with the assistance of the VCMA effect was further designed to perform magnetic field-independent logic operations. The numerical simulations were carried out, demonstrating the feasibility to realize all 16 Boolean logic functions in a single three-terminal device by applying the bias voltage and current injection as input variables. This approach provides a potential way toward the application of energy efficient spin-based logic, which is beyond the current von Neumann computing architecture.

We study the impact of Mg insertion layer at the CoFeB|MgO interface on the domain wall depinning field and motion as well as other magnetic properties in a perpendicular magnetized Ta/CoFeB/Mg(wedged)/MgO structure. With the increase of the Mg layer from 0.4 nm to 0.8 nm, the field-induced domain wall moving velocity increases while the depinning field decreases. The minimum depinning field of around 10 Oe for as-grown sample and 7 Oe for annealed sample is found with a 0.8 nm Mg insertion layer, which is 2 times lower than the ones reported before. Further increase of the Mg layer leads to a lower velocity and higher depinning field. Similar phenomena happens to the magnetic properties such as the saturation magnetization and perpendicular magnetic anisotropy. Both for as-grown and annealed samples, the tendency is similar. This may be explained by the oxidation and crystallinity manipulation of the CoFeB|MgO interface. These results show an ultra-low depinning field in the Ta/CoFeB/MgO system as well as a possible way for controlling the depinning field.

Magnetic skyrmions are topologically protected spin textures that exhibit many fascinating features. As compared to the well-studied cryogenic Bloch skyrmions in bulk materials, we focus on the room-temperature Néel skyrmions in thin-film systems with an interfacial broken inversion symmetry in this article. Specifically, we show the stabilization, the creation, and the implementation of Néel skyrmions that are enabled by the electrical current-induced spin-orbit torques. Towards the nanoscale Néel skyrmions, we further discuss the challenges from both material optimization and imaging characterization perspectives.

We studied the thermal stability of perpendicular magnetic anisotropy (PMA) in Ta/Mo/CoFeB/MgO/Ta films with and without inserted Mo layers. In the absence of a Mo layer, the films show PMA at annealing temperatures below 300 °C. On the other hand, the insertion of a Mo layer preserves PMA at annealing temperatures of up to 500 °C; however, a higher annealing temperature leads to the collapse of PMA. X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM) were used to study the microstructure of the films to understand the deterioration of PMA. The XPS results show that the segregation of Ta is partly suppressed by inserting a Mo layer. Once inserted, Mo does not remain at the interface of Ta and CoFeB but migrates to the surface of the films. The HRTEM results show that the crystallization of the MgO (001) texture is improved owing to the higher annealing temperature of the Mo inserted sample. A smooth and clear CoFeB/MgO interface is evident. The inserted Mo layer not only helps to obtain sharper and smoother interfaces but also contributes to the crystallization after the higher annealing temperature of films.

We studied the thermal stability of perpendicular magnetic anisotropy (PMA) in Ta/Mo/CoFeB/MgO/Ta films with and without inserted Mo layers. In the absence of a Mo layer, the films show PMA at annealing temperatures below 300 °C. On the other hand, the insertion of a Mo layer preserves PMA at annealing temperatures of up to 500 °C; however, a higher annealing temperature leads to the collapse of PMA. X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM) were used to study the microstructure of the films to understand the deterioration of PMA. The XPS results show that the segregation of Ta is partly suppressed by inserting a Mo layer. Once inserted, Mo does not remain at the interface of Ta and CoFeB but migrates to the surface of the films. The HRTEM results show that the crystallization of the MgO (001) texture is improved owing to the higher annealing temperature of the Mo inserted sample. A smooth and clear CoFeB/MgO interface is evident. The inserted Mo layer not only helps to obtain sharper and smoother interfaces but also contributes to the crystallization after the higher annealing temperature of films. [ABSTRACT FROM AUTHOR]