Spintronic devices: a promising alternative to CMOS devices

Abstract

The field of spintronics has attracted tremendous attention recently owing to its ability to offer a solution for the present-day problem of increased power dissipation in electronic circuits while scaling down the technology. Spintronic-based structures utilize electron’s spin degree of freedom, which makes it unique with zero standby leakage, low power consumption, infinite endurance, a good read and write performance, nonvolatile nature, and easy 3D integration capability with the present-day electronic circuits based on CMOS technology. All these advantages have catapulted the aggressive research activities to employ spintronic devices in memory units and also revamped the concept of processing-in-memory architecture for the future. This review article explores the essential milestones in the evolutionary field of spintronics. It includes various physical phenomena such as the giant magnetoresistance effect, tunnel magnetoresistance effect, spin-transfer torque, spin Hall effect, voltage-controlled magnetic anisotropy effect, and current-induced domain wall/skyrmions motion. Further, various spintronic devices such as spin valves, magnetic tunnel junctions, domain wall-based race track memory, all spin logic devices, and recently buzzing skyrmions and hybrid magnetic/silicon-based devices are discussed. A detailed description of various switching mechanisms to write the information in these spintronic devices is also reviewed. An overview of hybrid magnetic /silicon-based devices that have the capability to be used for processing-in-memory (logic-in-memory) architecture in the immediate future is described in the end. In this article, we have attempted to introduce a brief history, current status, and future prospectus of the spintronics field for a novice.

Design and analysis of SHE-assisted STT MTJ/CMOS logic gates

“…a AP to P switching of the MTJ, when J SHE and J STT flow along Y and -Z directions, respectively. b For P to AP switching of the MTJ, the direction of J SHE is the same while the direction of J STT has been reversed [2] power/energy consumption and the schematic of PCSA2 is shown in Fig. 4.…”

“…Spintronics is one of the emerging areas that use the spin property of an electron in association with its charge [1,2]. It has an extra degree of freedom for computation.…”

“…[68] utilize in-plane-MTJ (i-MTJ) rather than perpendicular-MTJ (p-MTJ). The i-MTJ suffers from disadvantages such as larger size, the difficulty for scaling, and low thermal stability, as compared to p-MTJ [2,70,71]. Further only AND and OR operations can be performed using the circuit proposed in Ref.…”

“…On the contrary, when the magnetic orientation of the PL and FL is pointing in the opposite direction, then the MTJ is in the anti-parallel state (AP) and the resistance state is represented as R AP . b Generation of pure spin current in the HM due to strong spin-orbit coupling illustrating the SHE effect [2] substantial spin current [36]. Largely, SHE was believed to be arisen due to the skew scattering of s-electrons [35,74], which is also known as an extrinsic mechanism.…”

“…Accurate switching in p-MTJ can be achieved by the application of either an external magnetic field or a STT current. From the literature, it is clear that generation and maintenance of the external magnetic field is undesirable from a practical point of view due to its design complexity, reduced sensitivity, and thermal stability [2]. Hence, using STT current in conjunction with SHE is a more suitable option for precise switching in p-MTJ [61].…”