On page 1989, chemists report creating tiny carbon-coated metallic particles--each just 4 nanometers, or billionths of a meter, across--that they bake into a magnetic film that could be used in hard disk drives. Down the road, if each of the tiny particles can be made to store a bit of information as a magnetic field, the films have the potential to hold terabytes of data per square inch, hundreds of times the capacity of today9s disk drives.