DOW-UAP-D129, AAWSAP DIRD, Metallic Spintronics, March 2010
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.
The summary above is sourced from the released file metadata as published to war.gov. The analysis sections below are original to this tracker.
Text of the document
Machine-extracted from the PDF war.gov published (its text layer or OCR), so expect errors, especially in names, numbers and handwriting; the PDF is the authoritative copy. Lines that did not extract as readable text are left out. Showing about 994 words from pages 2, 3, 4, 5, 6 of 27.
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Metallic Spintronics Prepared by: Acquisition Support Division (DW0-3) Defense Warning Office Directorate for Analysis Defense Intelligence Agency Administrative Note COPYRIGHT WARNING: Further dissemination of the photographs In this publication Is not a.uthorlzed. This product is one in a series of advanced technology reports produced in FY 2009 under the Defense Intelligence Agency, Defense Warning Office's Advanced Aerospace Weapon System Applications (AAWSA) Program. Comments or questions pertaining to this document should be addressed to!AAP Person 1 AAWSA Program Manager, Defense Intelligence Agency, ATTN: CLAR/DW0-3, Bldg 6000, Washington,
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3.4 STT-Driven Motion of Magnetic Domain Walls ........................................... 12 Figure 1. In a Magnetic Multilayer, Several Atomic Layers of Magnetic Material Alternate With Layers of Nonmagnetic Material ...................................... 1 Figure 2. Resistance of a Magnetic Multilayer R Versus Magnetic Field .................. 2 Figure 3. Differential Resistance dV/dI of a Mechanical Point Contact as a Function of Current for a Series of Magnetic Fields................................................ 4 Figure 6. Torques on a Magnetic Moment in a Magnetic Field and Subject to an Electrical Current......................................................................... 7 Figure 9. Scanning Transmission X-ray Microscopy Images ................................. 10 Figure 12. Schematic of Point Contact to Sample Geometry ................................. 15
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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 (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,
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Spintronics is a broad research field with (currently) three major subfields: (1) materials research that is attempting to create new materials that are both magnetic and semiconductors, (2) research on novel magnetotransport effects in ferromagnetic metals, and (3) research on techniques that can be used to manipulate individual electron spins. The first subfield is targeting magnetic semiconductors because devices based on such materials would be the easiest to integrate with the present semiconductor device technology and processing capabilities. However, despite extensive research, most semiconductor spintronic devices are still theoretical concepts awaiting experimental demonstrations. This report focuses on spintronics research in metallic systems within the scope of the second and third subfields. The second subfield has experienced an unprecedented period of new discovery over the past 20 years, including the discovery of GMR, and has already spawned major technological change in the information storage industry with the use of GMR sensors and read heads. The third subfield is vital for spintronic devices, as virtually any processing of information in such devices is associated with transport and manipulation of spins. New and efficient methods for manipulating spins that stimulate active research programs in spintronics at a large number of academic institutions and a half-dozen industrial research labs around the world are highly desirable. The prize to be gained is active control and manipulation of spin distributions (magnetic moments) for new and improved functionality in electronic/spintronic devices. The confluence of intense basic science and industry interest in ferromagnetic metal spintronics has not occurred on this scale in physics in a long time. The report is arranged as follows: Section 2 is dedicated to magnetotransport effects in magnetic systems where magnetic configuration can influence the system's transport properties. It discusses GMR in magnetic multilayers and related phenomena, highlights basic physical principles responsible for GMR, and describes technological applications of the effect. Section 3 focuses on the reverse connection between the system's magnetic configuration and its transport properties-the so-called STT effect. The physical origin and potential applications are discussed. Section 4 discusses other new directions in metallic spintronics, with a particular focus on spintronics with antiferromagnetic materials. Section 5 summarizes, with an eye to the future, the development of spintronic technologies and their aerospace applications.
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2. Giant Magnetoresistance This section discusses the phenomenon of giant magnetoresistance (GMR). Excellent reviews of GMR are available elsewhere (Reference 12-22). The focus on physical concepts important for the sections to follow are discussed. GMR in magnetic multilayers refers to a dramatic reduction in the resistance of the multilayers when subjected to an external magnetic field. GMR's size is usually defined as the resistance change in magnetic field relative to its peak value. The effect can be distinguished from the ordinary magnetoresistance (MR) coming from the direct action of the magnetic field on the electron trajectories via the Lorentz force (Reference 23),
Where this file fits in the PURSUE archive
This file is one of DoD's 282 files in the Trump PURSUE disclosure. Within the DoD agency block it ranks #245 of 282 by Anomalousness Index. Across the entire 478-file archive it ranks #420 of 478.
That places it in the lower-scoring band of the archive (420 of 478 by score), typical of investigative-record style files where the report is paper-based rather than instrumented.
Anomalousness Index: 53/100
This is a reference document, not an encounter report, so the index has no encounter to measure here. The value above is the rubric's default for a document that describes no event, shown so every file in the archive can be ranked the same way. Not a probability of extraterrestrial origin - that number is not honestly computable from the released files and this tracker refuses to publish it.
🤖 AI-ASSISTED SCORING · methodology
The six rubric components break down for this file as follows. Each component has a weighted contribution to the final score; the per-component explanation below describes what this file's particular value on that component means in the rubric's framework.
This file is a reference document, not an observation, so no sensor, camera, or witness captured anything. The rubric's sensor axis has no not-applicable option, so a document with no instrument record sits on its lowest tier by default.
There is no witness: this is a document released by the Department of War, not a first-hand account. The rubric assigns this axis from the originating body, so the value reflects the source of the record, not anyone's testimony.
Nothing is being corroborated, because the file does not report an event. Like every file in the archive it takes the rubric's single-source default.
The file describes no object and no motion, so the kinematic axis takes the archive-wide 'no kinematic data' default.
Every file in the archive scores this tier. For a document that describes no event it carries no information about the record at all.
The rubric's default for the file's release status (files released with redactions are catalogued as unresolved, unredacted ones as open). For a document that reports no event this describes how the file was released, not anything that happened.
Bottom line on the score: the 53/100 is the rubric's default for a document that reports no encounter, so it is not a finding about any event and should not be compared with the scores of sighting reports. For the full per-axis weights and the rubric JSON, see /methodology.
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