The discovery soon had the attention of researchers around the world because of its potential for improving hard drives. Stuart Parkin, a scientist at IBM Research, discovered that the effect could be achieved using much faster, cheaper methods than those used by Fert and Grünberg. Meanwhile, several other technologies had to be developed to take advantage of giant magnetoresistance, including techniques for writing smaller bits and for moving the read/write heads more precisely. A key discovery by researchers at IBM was a new configuration of magnetic layers that made it possible for the effect to be produced with small magnetic fields and used in the tiny read/write heads of hard drives.
The first disk drive based on GMR, a 16-gigabyte hard drive made by IBM, appeared in 1997. Over the next 10 years, the technology led to 1,000-gigabyte (one-terabyte) hard drives, says John Best, now the chief technologist at Hitachi Global Storage Technologies in San Jose, CA. He led the group at IBM that developed the first read/write head technology based on GMR. (The most recent of these hard drives make use of a related effect called tunneling magnetoresistance; like GMR, it makes use of magnetic layers oriented in opposite directions, but it is even more sensitive.)
The GMR effect could be the key to several more generations of memory devices, Best says. As researchers develop novel ways of packing more bits onto a hard drive, leading to disks potentially 50 times as dense as those available today, GMR-related technology will continue to be used to detect these bits, he says. The property is also crucial for new types of devices, including magnetic random access memory (MRAM), which is nonvolatile like flash memory, but faster and more reliable. Another experimental technology called racetrack memory, which is now being developed by Parkin, uses a novel type of memory bit, but one that could still be read using a GMR-based device, he says. Racetrack memory could eventually combine the best features of hard drives, flash drives, and conventional random access memory, serving as a universal memory device. (See “A Better Memory Chip” and “IBM Attempts to Reinvent Memory.”)
Indeed, in awarding the prize, the Nobel committee pointed to the wide-ranging importance of GMR in opening up the new science of spintronics, in which both the charge and spin of electrons is manipulated. The discovery, which the committee describes as one of the first payoffs of nanotechnology, has in turn now become “a driving force for new applications of nanotechnology.”