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Technologies based on magnetic skyrmions such as novel computational devices that can operate at high speed or low energy consumption have been proposed by many researchers.Recently, synthetic antiferromagnetic (SyAF) structures have been proposed to increase the stability and mobility of skyrmions by reducing or eliminating the skyrmion Hall effect. Here, we numerically study the current-induced dynamics of skyrmions on SyAF bilayer structures.We demonstrate the effective control and manipulation of SyAF skyrmions, including the directional displacement and alignment. Besides, we design SyAF skyrmion-based logic gates such as the AND, OR, XOR and NOT gates. Our design provides guidance for future development of spintronic computing devices that use topological nanoscale spin textures as information carriers.

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We report a p24 (HIV disease biomarker) detection assay using an MgO-based magnetic tunnel junction (MTJ) sensor and 20-nm magnetic nanoparticles. The MTJ array sensor with sensing area of 890 × 890 μm2 possessing a sensitivity of 1.39 %/Oe was used to detect p24 antigens. It is demonstrated that the p24 antigens could be detected at a concentration of 0.01 μg/ml. The development of bio-detection systems based on magnetic tunnel junction sensors with high-sensitivity will greatly benefit the early diagnosis of HIV.

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Skyrmion-based devices are promising candidates for non-volatile memory and low-delay time computation. Many skyrmion-based devices execute operation by controlling skyrmion trajectory, which can be impeded by the skyrmion Hall effect. Here, the design of skyrmionbased arithmetic device built on synthetic antiferromagnetic (SyAF) structures are presented, where the structure can greatly suppress skyrmion Hall effect. In this study, the operations of skyrmion-based half adder, full adder and XOR logic gate are executed by introducing geometric notches and tilted edges, which can annihilate or diverge skyrmion. Performance of these skyrmion-based devices are evaluated, where the delay time and energy-delay product of the single-bit full adder are 1.95 ns and 2.50 × 10 −22 Js , which are only 12% and 79% of the previously proposed skyrmion-based adder. This improvement is significant in the construction of ripple-carry adder and ripple-carry adder-subtracter. Therefore, our skyrmion-based SyAF arithmetic device are promising candidate to develop high-speed spintronic devices.