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.