Spintronics for achieving system-level energy-efficient logic

The demand for data processing in high-performance computing is growing rapidly. Extrapolating these trends to the long term suggests that a switch, which is more energy-efficient than a silicon complementary metal-oxide semiconductor (CMOS) switch, is necessary to support future computing needs. Spintronic logic, which encodes information using spin and magnetism, can theoretically provide an energy-efficient switch; however, it is less mature than CMOS logic and has yet to be realized at the level of a full processor system, thus warranting an informed review of spintronic logic technologies with guidelines for future research directions. In this Review, we contextualize spintronic logic within the broader goals of beyond-CMOS computing. We then provide an overview of five types of spintronic logic, discussing the operating principles, advantages, advancements and challenges of each type. We highlight that future research in spintronic logic should focus on the realization of low-voltage operation, transparent benchmarking for application-level tasks, development of computing architectures that exploit unique features of spintronics such as non-volatility and high endurance, and adaptation of spintronic logic to circuits usable for both computing and memory. This Review provides motivation and direction for high-risk, high-reward research in spintronic logic that should be pursued in parallel with the CMOS road map. This Review showcases the research progress and prospects of spintronic logic, which encodes information using spin and magnetism. Focusing on five exemplary types, we discuss the promise, challenges and future research directions in the context of high-performance computing needs.