Technological Impact
Exchange bias was initially used to stabilize the magnetization of soft ferromagnetic layers in readback heads based on the anisotropic magnetoresistance (AMR) effect. Without the stabilization, the magnetic domain state of the head could be unpredictable, leading to reliability problems. Currently exchange bias is used to pin the harder reference layer in spin valve readback heads and MRAM memory circuits that utilize the giant magnetoresistance or magnetic tunneling effect. Similarly the most advanced disk media are antiferromagnetically coupled, making use of interfacial exchange to effectively increase the stability of small magnetic particles whose behavior would otherwise be superparamagnetic.
Desirable properties for an exchange bias material include a high Néel temperature, a large magnetocrystalline anisotropy and good chemical and structural compatibility with NiFe and Co, the most important ferromagnetic films. The most technologically significant exchange bias materials have been the rocksalt-structure antiferromagnetic oxides like NiO, CoO and their alloys and the rocksalt-structure intermetallics like FeMn, NiMn, IrMn and their alloys.
Read more about this topic: Exchange Bias
Famous quotes containing the word impact:
“As in political revolutions, so in paradigm choice—there is no standard higher than the assent of the relevant community. To discover how scientific revolutions are effected, we shall therefore have to examine not only the impact of nature and of logic, but also the techniques of persuasive argumentation effective within the quite special groups that constitute the community of scientists.”
—Thomas S. Kuhn (b. 1922)