SAN JOSE, Calif. A professor at Carnegie Mellon University is developing a technology seen as a dark horse in the race toward tomorrow's ultra-dense hard disk drives. Jimmy Jian-Gang Zhu is developing a prototype of his microwave-assisted magnetic recording (MAMR) technique he believes will pack three terabits of data in a square inch of a spinning disk.
The technique represents a third option in an ongoing debate over the next big shift in hard disk technology expected to emerge in the next year or two.
Seagate Technology has been championing an approach called heat-assisted magnetic recording (HAMR) that uses a tiny laser light on each drive head to heat a portion of the disk just before a write operation. Rival Hitachi Global Storage Technologies is working on a way to pattern tracks and even bit locations on media.
All sides say they are actively exploring both technologies. Ultimately both technologies will be needed to deliver disks that pack 10 terabits or more per square inch.
Using perpendicular recording, drive makers are now shipping units that pack 530 Gbits per square inch. One analyst said the industry may have to choose within the next year one of the contending approaches to get to 1 Tbit/square inch and beyond.
Either patterned media or heat-assisted recording could deliver densities of 1-10 Tbits per square inch and have similar costs based on today's rough estimates. Zhu of Carnegie Mellon believes his approach could cost less than either approach and provide similar gains.
"What is needed to convince the industry is an experimental demonstration [and my lab] is in the process of fabricating such device and testing its performance," Zhu said in an email exchange.
Using MAMR, a drive head emits a microwave field that excites the electrons in the media building up energy that eases the process of writing data. The process uses a localized high frequency ac magnetic field generated by a magnetic thin film stack integrated with existing recording heads.
The stack consists of "a few more magnetic layers within the present recording heads and the additional process will only increase the complexity of the recording heads by 10 percent or less," said Zhu. Thus MAMR "represents the least disruptive approach with substantial gain of storage capacity," he added.
The patent office recently awarded the university a patent on a spin torque oscillator it uses to implement its film stack. "I am sure that every HDD company is starting some sort of effort to investigate this technique," Zhu said.
Indeed Hitachi GST and others have published papers on versions of MAMR.