History 2001: AntiFerromagnetic-Coupled Exchange Media Available Now

“AntiFerromagnetic-Coupled exchange media (AFC) has the potential to extend the superparamagnetic effect to 100Gb per square inch or higher,” revealed Dr. Ed Grochowski, program manager of storage devices, IBM Almaden research center, San Jose, CA.

AFC uses exchange, which is also used in GMR heads.

The new longitudinal media employs a thinner stabilizing magnetic layer below the usual recording magnetic layer. The stabilizing layer couples antiferromagnetically with the recording magnetic layer, through a thin ruthenium (Ru) space layer. Such AFC media are also called synthetic ferromagnetic media or laminated antiferromagnetically coupled media.

When we asked him: “Is there a prototype already at IBM?,” Grochowski responded yes, and that the technology is even available now. “As a prototype?” we wondered. “No, as a product,” he confirmed. “It has not been announced yet. I am not announcing the product, rather just that I believe that the technology is available now. IBM will issue a white paper soon.”

Grochowski also indicated that IBM would soon propose an increase in HDD blocks, from 500B to 4,000B. “Today all disk drives use the 512B blocks,” he explained. “A portion of the total storage is overhead, the ECG error correction. As I increase areal density, I need more and more ECG. The 512 block is too small, because a significant portion of the data storage will be used for ECG, higher than 5%. The proposal that we are making to the industry is to change the data block size to 4K or 4B to go back to the 5% ECG. It also opens the door for more sophisticated error correction codes.”

This article is an abstract of news published on issue 160 on May 2001 from the former paper version of Computer Data Storage Newsletter.