Magnetoresistance - Fodder for Micro Hard Drives
at SUNY, Buffalo, NY, have revealed the potential of an effect known as "ballistic
magnetoresistance," whereby applying atomic-dimension "nanocontacts" to magnetic
media resulted in a 3,000% change in magnetoresistance at low switching fields of
a few hundred oersted. This has the potential to increase hard drive storage densities
from GBits/in² to TBits/in². Interior magnetic-domain walls measure about 1 nm vs.
100 to 200 nm for a normal conductor. Electrons forced through such a small conduit
literally do not have space to bounce around inside the conductor and producing
heat. With a nanocontact's 1 nm wide domain walls, electrons stream through, creating
a draft-like effect that prompted the label "ballistic." Look for thumbnail-size
hard drives in about a decade.