Number 142 (Story #3), September 1, 1993 by Phillip F. Schewe and Ben Stein GIANT MAGNETORESISTANCE (GMR) , the change of a material's electrical resistance caused by an applied magnetic field, can now be produced with low fields. Scientists at IBM ADSTAR in California have developed a structured material using nickel, iron, and silver atoms stacked in nm-thick layers, with neighboring layers having oppositely oriented magnetizations. The new material shows a 4-6% resistance change in applied fields of only 5-10 oersteds (at room temperature) rather than the 250 oersteds used previously. GMR studies, only 5 years old, are expected to lead to an increase in the density of data that can be stored in magnetic media. (Science, 20 August.)