Magnetically engineered spintronic sensors and memory

TLDR

Enhanced magnetoresistance and oscillatory interlayer exchange coupling in transition‑metal multilayers have spurred the creation of spintronic thin‑film materials that manipulate spin‑polarized electrons via magnetic‑field‑controlled moment orientation, enabling advanced magnetic sensors and memories and hinting at further applications such as hot‑electron tunnel transistors. Spin‑valve GMR sandwiches with artificial antiferromagnetic reference layers have dramatically increased hard‑disk storage capacity, while MTJ devices have produced high‑performance nonvolatile magnet‑RAM with densities near DRAM and read‑write speeds comparable to SRAM.

Abstract

The discovery of enhanced magnetoresistance and oscillatory interlayer exchange coupling in transition metal multilayers just over a decade ago has enabled the development of new classes of magnetically engineered magnetic thin-film materials suitable for advanced magnetic sensors and magnetic random access memories. Magnetic sensors based on spin-valve giant magnetoresistive (GMR) sandwiches with artificial antiferromagnetic reference layers have resulted in enormous increases in the storage capacity of magnetic hard disk drives. The unique properties of magnetic tunnel junction (MTJ) devices has led to the development of an advanced high performance nonvolatile magnet random access memory with density approaching that of dynamic random-access memory (RAM) and read-write speeds comparable to static RAM. Both GMR and MTJ devices are examples of spintronic materials in which the flow of spin-polarized electrons is manipulated by controlling, via magnetic fields, the orientation of magnetic moments in inhomogeneous magnetic thin film systems. More complex devices, including three-terminal hot electron magnetic tunnel transistors, suggest that there are many other applications of spintronic materials.