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Defense Intelligence Reference Document Metallic Spintronics

Defense Intelligence Agency · 27 pages · text from the file's own layer

This Defense Intelligence Reference Document, dated 23 March 2010 and produced by the Defense Intelligence Agency under its Advanced Aerospace Weapon System Applications (AAWSA) program, is a technical report on metallic spintronics. It explains giant magnetoresistance, spin-transfer torque and antiferromagnetic spintronics, along with their uses in sensors, hard drive read heads and magnetic memory. It concludes that spintronic devices could enable low-power, radiation-resistant electronics suited to aerospace and long space missions.

  • p. 8 …In order to increase the resistances to easily observable values, microfabrication techniques can be used to…
  • p. 10 …single-spin Sis negligibly small owing to S being negligibly small compared with M. For high…
  • p. 12 …For instance, in modest external magnetic fields, magnetization of a small element can be repeatedly reversed…
  • p. 13 …The ultimate result can be either stable steady-state precession of S around B•ff (black…
  • p. 16 …However in scaling MRAM to small dimensions, the same constraints are expected to drive a transition…
  • p. 18 …While AGMR of an AFM spin valve was predicted (Reference 84) to be similar in magnitude…
  • p. 19 …Small MRs observed at higher currents in films with F layers may be associated with the…
  • p. 20 …Magnetic coupling between the two F layers should be negligible, because the N layer is thick…
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pulses (STT switching). Figure 9 shows scanning transmission x-ray microscopy
(Reference 53) images of in-plane components of magnetization M - Mx in panel (a)
and My in panel (b}-in the free CoFe layer (indicated by blue ellipse) of a 100x150-nm2
magnetic nanopillar. The images were obtained by scanning a focused (diameter~ 30
nm) circularly polarized x-ray beam across the CoFe layer, with the photon energy
tuned to the characteristic Co L3 resonance to provide magnetic contrast through the x-
ray magnetic circular dichroism effect (Reference 54), and by monitoring transmission
of the x-rays as a function of the position x, y with a fast avalanche detector. The M- -
vector field of the free layer can be reconstructed from the measured Mx and Mv
components as illustrated in Figure 9c, and the ultrafast x-ray microscopy technique
provided a means to monitor this field as a function of time with ~100-picosond
resolution. The spatial resolution of the technique is set by the spot size of the x-ray
beam (~30 nm) and currently limits its application to spintronic devices >100 nm in
size (Reference 52). Potentially, however, technical development of the ultrafast.x-ray
microscopy may lead to an ultimate technique for STT studies that can probe the M-
vector field on the nanometer length scale with picosecond time resolution.
(a) (b) (c)
Figure 9. Scanning transmission 1 100 GHz by changing
the applied magnetic field and/or the de current, effectively resulting in a current-
controlled oscillator for use in practical microwave circuits. Hence, the SIT effett in
10
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Report, from the dia collection. The PDF is mirrored here; the original link is under it. 27 pages are in the text index: search them above, or from the library's search.