The key to IBM's new data storage breakthrough is a threeatom-thick layer of the element ruthenium, a precious metal similar to platinum, sandwiched between two magnetic layers. That only a few atoms could have such a dramatic impact caused some IBM scientists to refer to the ruthenium layer informally as "pixie dust". Known technically as"antiferromagnetically-coupled (AFC) media," the new multilayer coating is expected to permit hard disk drives to store 100 billion bits (gigabits) of data per square inch of disk area by 2003. Current hard drives can store 20 gigabits of data per square inch. IBM began shipping Travelstar hard drives in May 2001 that are capable of storing 25.7 gigabits per square inch. Drives shipped later in the year are expected to be capable of 33% greater density