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Spin Wave Logic Devices
Published in Evgeny Y. Tsymbal, Igor Žutić, Spintronics Handbook: Spin Transport and Magnetism, Second Edition, 2019
Alexander Khitun, llya Krivorotov
In conclusion, Boolean-type spin wave logic devices provide an alternative approach to logic circuit construction by exploiting the intrinsic non-linearity of magnetic materials. In contrast to spin-FETs, most magnonic devices do not require highly efficient spin injection, and room temperature–operating prototypes have been demonstrated. Non-volatility is the main advantage inherent in all spin wave device schemes, which may potentially eliminate the need for static power consumption. The future success of spin wave logic is mainly tied to the realization of the most energy-efficient mechanism for local magnetization control. The development and use of multiferroic materials is a promising approach capable of scaling down energy per magnetization reversal to the attojoule level. At the same time, the use of nanomagnets for information storage implies certain limits on the operation speed, which is restricted by the time required for magnetization reversal. It is unlikely that devices based on ferromagnets will be able to compete with CMOS in speed. Nevertheless, magnetic logic circuits can provide higher functional throughput or perform the same data processing tasks with lower energy consumption than CMOS by implementing complex logic functions and/or reconfigurability.
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Published in Sarhan M. Musa, ®, 2018
Shin-Liang Chin, Flack Timothy
Cowburn [19] and Allwood et al. [20] showed that nano-magnetic materials can be used to construct magnetic logic gates. Just like the conventional electronic logic gates, these magnetic logic gates perform basic logic operations such NAND, NOT, and NOR but instead of using electronic charge they use magnetization. One such way to achieve this is by using nano-magnetic dots [21] and the cellular automata architecture [22]. There have also been proposals to use domain wall motions in carefully designed magnetic nanowires as magnetic logic gates. In many of these researches, a popular finite difference micromagnetics simulation software called OOMMF [23] is used to verify the experimental results.
Recent advances in two-dimensional ferromagnetism: strain-, doping-, structural- and electric field-engineering toward spintronic applications
Published in Science and Technology of Advanced Materials, 2022
Sheng Yu, Junyu Tang, Yu Wang, Feixiang Xu, Xiaoguang Li, Xinzhong Wang
Additionally, the electric-field control of interlayer magnetism in 2D layered structure have been widely reported with regard to three aspects. First, the multiple magnetic states can be induced by external electric field as a result of different patterns of layer magnetizations without breaking the magnetism of individual layer. Second, the electric field can switch the interlayer spin states and reconfigure the spin filters, indicating a great potential for magnetic logic gate device. Lastly, electric field can also induce some novel magnetic configurations, such as Skyrmion ferromagnetism in CrI3 [125] and spiral ferromagnetism in twisted bilayer graphene [126]. Mak et al. [127] demonstrated electrostatic doping effect on the magnetic properties of bilayer CrI3 by using graphene/CrI3 vertical heterostructure. Doping can significantly modify the interlayer exchange coupling, coercive field and Tc, showing that electron/hole doping can weaken/strengthen the long-range magnetic order. The antiferromagnetic phase monotonically diminished with increasing electron doping concentration and then, totally vanished and turned into ferromagnetic phase after the elevated electron doping reaches ~2.5 × 1013 cm−2 (Figure 6(h–j)). Mak et al. [128] also demonstrated an effective regulation of magnetism via applying transverse electrical field in bilayer antiferromagnetic CrI3. They observed that the external electric field can induce a linear magnetoelectric effect as a result of interlayer potential difference. Xu et al. [129] used magneto-optical Kerr effect microscopy to study the electrostatic gate effect on the magnetism in CrI3 bilayers. They obtained electrical switching between ferromagnetic and antiferromagnetic states by applying magnetic fields near the metamagnetic transition. They also demonstrated that, due to the strong spin-layer locking, the linear gate-dependent Kerr effect signals with opposite slopes could occur with a time-reversal pair of layered antiferromagnetic states without external magnetic field. Xu et al. [130] reported the electrical switching of multiple magnetic states in four-layer CrI3 sandwiched between two bipolar graphene electrodes in a dual-gated field effect device. They also observed an effective gate-modulation on TMR from 17,000% to 57,000%, which is tentatively attributed to the combination of magnetic proximity effect at graphene/CrI3 interface and electrical field modulation on the spin-dependent tunneling as a result of Fermi level shift. San-Jose et al. [126] proposed that the relative lattice orientation between adjacent graphene layers can modulate the magnetic phases in twisted graphene bilayers. It shows a magnetic transition from lattice AFM phase to spiral FM phase for twisting graphene bilayers from 0° to a relative 120° misalignment. The vertical electric field can effectively switch the spiral FM phase and the lattice AFM phase with a relative 120° misalignment as a result of electrically tuned exchange coupling between adjacent graphene layers.