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AAWSAP DIRD, Metallic Spintronics, March 2010

U.S. Department of War · 2010-03-23 · 27 pages · text from the file's own layer

The Defense Intelligence Agency's Defense Warning Office issued this Defense Intelligence Reference Document, dated 23 March 2010, as one of a series of advanced technology reports produced in FY 2009 under its Advanced Aerospace Weapon System Applications Program. The report reviews metallic spintronics, including giant magnetoresistance, spin-transfer-torque and antiferromagnetic spintronics, along with their applications. It concludes that spintronic devices could offer radiation-resistant, low-power electronics suited to aerospace use and long space trips.

From the source: Release of 2026-09-18 Incident: 3/23/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys metallic spintronics, a branch of electronics that seeks to use both the electric charge and the magnetic spin of electrons to store, detect, and manipulate information, and argues that the field could lead to faster, lower-power, and more radiation-resistant devices than conventional semiconductor electronics. The report focuses on two main effects: giant magnetoresistance (GMR), which allows magnetic states to be read through changes in electrical resistance, and spin-transfer torque (STT), which allows electrical currents to change those magnetic states. The DIRD reviews their underlying physics, the experimental work then available, and possible applications in memory, sensors, oscillators, and logic devices. The document treats metallic spintronics as a promising field while emphasizing that many of its more advanced proposed applications still require substantial further development.

UNCLASSIFIED/ /POK orr1e1At tt!I!! er~LY
Metallic Spintroni·cs
1. Introduction
The rapid pace of progress in the computer industry over the past 40
years has been based on the miniaturization of chips and other
computer components. Further miniaturization, however, faces
serious challenges-for example, increasingly high power dissipation.
To continue on pace, the industry must g,o beyond incremental
improvements and embrace radically new technologies. A promising
nanoscale technology known as spintronics (a neologism for "spin
based electronics"} has emerged. Spintronics refers to the role an
electron spin plays in solid-state physics. Spintronics researchers
aim to develop a revolutionary new class of electronic devices based
on the spin of electrons in addition to the charge. In spintronic
devices, information is carried not by the electron's charge, as in
conventional microchips, but by the electron's intrinsic spin.
Changing the spin of an electron is faster and requires less power
than moving it. Therefore, if a reliable way could be found to control
and manipulate spins, spintronic devices could offer higher data
processing speeds, lower electricity consumption, and many other
advantages over conventional chips, perhaps including the ability to
carry out radically new quantum computations.
Spintronics in ferromagnetic systems is built on a complementary
set of phenomena in which the magnetic configuration of the system
influences its transport properties and vice versa. Giant
magnetoresistance (GMR} (Reference 1, 2} and spin-transfer-torque
(STT} (Reference 3-5} phenomena exemplify such interconnections
in multilayers composed of ferromagnetic (F} and nonmagnetic (N)
layers. The physics and applications of metallic spintronics are
discussed in this report from the perspec:tive of these two
phenomena. GMR, research on which was awarded the Nobel Prize in
Physics in 2007, refers to a large change in resistance of magnetic
multilayers when the relative orientation of magnetic moments in
their constituent ferromagnetic layers is altered by an applied
magnetic field. The inverse effect, STT, in which a large electrical
current density j can perturb the magnetic state of a multilayer, has
also been predicted (Reference 3, 4} and observed in experiments on
current-induced reversal and precession of magnetization
(Reference 5-9} and magnetic domain wall motion (Reference 10,
11}.
UNCLASSIFIED/ }FOR OFFICiI.ALi !9&i ODIL;¥
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 27 pages are in the text index: search them above, or from the library's search.