Researchers from LBL, from IBM Corporation's research centers in San Jose, Calif., and in Zurich, Switzerland, from the University of Neuch tel, Switzerland, and Arizona State University report their achievement in the February 11 issue of the journal Science. This and other findings hold promise for the fabrication of improved magnetic devices. Yellow and blue indicate the magnetic moment parallel and perpendicular to the photon polarization, respectively. As the head passes over the hard disk, these layers sense the orientation of the domains on the disk and cause the head's electrical resistance to change in response. When the head's ferromagnetic layers share the same magnetic orientation, there is less electrical resistance than when they are magnetically opposed.
Nobody really knows the mechanism that couples the ferromagnet to the antiferromagnet.
To study magnetic materials in microscopic detail, the researchers needed a tool with very high spatial resolution and one that was sensitive not only to the orientation of magnetic and antiferromagnetic domains, but also to surfaces and interfaces, and could distinguish one kind of atom from another. The energy of the illuminating beam can be tuned to pick out specific elements for example, iron emits electrons with most intensity when the photons in the beam have an energy of about 710 electron volts. The soft x-ray beam can be polarized circularly or linearly. Circular polarization is used to image ferromagnetic materials whose domains have their magnetic spins aligned in the same direction. To image antiferromagnetic domains, in which spins are aligned opposite to each other, linear polarization is needed.