Metallic Spintronics

This Defense Intelligence Reference Document, dated 23 March 2010, provides a technical overview of metallic spintronics, a field of study focused on utilizing the intrinsic spin of electrons for electronic devices. The document was produced under the Defense Intelligence Agency's Advanced Aerospace Weapon System Applications (AAWSA) program. The report details two primary phenomena: Giant Magnetoresistance (GMR) and Spin-Transfer-Torque (STT). GMR, which involves a change in electrical resistance in magnetic multilayers based on the orientation of magnetic moments, has already significantly impacted the information storage industry through its use in read heads. STT, a more recent development, involves using electrical current to manipulate magnetic moments at the nanoscale. The report explores the physics behind these effects, including the two-current model and the Landau-Lifshitz-Gilbert equation. Potential applications for spintronic technologies are discussed, including high-frequency oscillators, high-density magnetic random access memory (MRAM), and racetrack memory. The document emphasizes that spintronic devices offer advantages over conventional CMOS transistors, such as higher data processing speeds, lower electricity consumption, and increased radiation resistance, making them particularly attractive for aerospace applications where radiation can damage conventional electronics. The report also touches upon emerging research into antiferromagnetic metal spintronics, which may offer further improvements in control and fabrication. The document concludes that while the field is in its infancy, the confluence of basic science and industrial interest suggests significant future potential for these technologies.