Chapter 9 - 5

05 Computer Science

Giant Magnetoresistance

Hard drives and storage devices produced in the past fifteen years have been significantly smaller than their predecessors.

This change would not have been possible without the contributions of European scientists Albert Fert and Peter Grunberg.

The two men, independent of each other, discovered a previously unobserved phenomenon in physics.

It would change the face of technology and its practical applications in everyday life.

The phenomenon they observed was dubbed Giant Magnetoresistance (GMR).

Although seemingly simple, it had remained undiscovered until they observed it in 1988.

Their observation was based on the principle that electricity and magnetism are directly associated.

Both scientists discovered that very small changes in magnetic resistance could result in rather dramatic changes in corresponding electrical resistance.

While it may not seem immediately relevant to technology, the discovery was important in creating small devices capable of holding large amounts of data.

The hard drive of a computer is the best example of how the discovery of GMR changed everyday technology.

The data stored on hard drives is encoded on a metal disk. An encoding process magnetizes small sections of the disk, which in turn are translated into data when the magnetized disk is read by a sensor.

The sensor translates the magnetic data into electric signals.

Hard drives prior to the discovery of GMR were significantly larger than those we have today.

Although they operated based on the same basic relationship of magnetism and electricity, it was difficult for sensors to discern between separate pieces of data without a very large disk.

Therefore, the disks used for high-capacity hard drives were much larger than a dinner plate.

The insights of GMR, however, allowed engineers to shrink the hardware, while retaining and even increasing the storage capacity.

Using the principle discovered by Fort and Grunberg, the first hard drive using GMR technology was released in 1997.

It quickly became the standard, thanks to its compact size.

The insights of GMR allowed engineers to increase the sensitivity of the sensor heads on hard drives.

As a result, the size of the magnetic strips of data on a hard drive could be drastically reduced.

In fact, these sensor heads are so sensitive that the magnetized strips of data may only be a few atoms thick.

The discovery and implementation of GMR would not have been possible without discoveries that allowed very thin material of this small size to be produced.

GMR hard drives put a very thin layer of magnetic material on an otherwise nonmagnetic disk, which can then be read by a fine-tuned sensor head.

The contribution of GMR to modern technology was massive.

Hard drives prior to the application of the technology were much larger in size and relatively small in storage capacity.

High-capacity drives were something as large as chairs. With the new technology, hard drives the size of a human hand could be engineered to hold as much data as their high-capacity, non-GMR counterparts.

Furthermore, researchers quickly found that additional magnetic layers, separated by a nonmagnetic layer, could be used to store even more data.

Since the additional layer is only a few atoms thick, it does not substantially change the size of the hard drive.

Additionally. the development has been accredited with contributing to the field of nanotechnology, an emerging technology concerned with the engineering of microscopic devices.

Since GMR requires hard drives to use a disk plated on a magnetic material only a few atoms thick, it contributed to technology that is now being used to engineer complex mechanical devices of a similar thickness.

The impact of the discovery of GMR has had a lasting impact on technology.

The sensor heads of even the most up-to-date hard drives still use the basic principles of GMR.

Perhaps the most apparent benefit of the technology has been its impact in the world of mobile computing.

Whereas laptop computers of the last decade were incredibly large and bulky, today’s laptop computers are less than an inch thick.

The end result of the discovery of GMR is still not completely apparent.

We continue to use it in everyday technology, but that technology is constantly being honed and improved with time.

As such, it is unlikely that we have seen the last of what GMR has to offer us.