The disk drive industry had big news to celebrate on Oct. 12.
Drs. Albert Fert and Peter Grünberg were awarded the $1.5 million 2007 Nobel Prize for physics by discovering GMR (giant magnetoresistance)—a key physical technology now widely used in HHD (Hybrid Hard Drive) development and manufacturing.
GMR is a quantum mechanical effect observed in atoms-thin structures composed of alternating ferromagnetic and nonmagnetic metal layers.
Grünberg and Fert were the first to discover how to use GMR to manipulate the magnetic and electrical properties of thin layers of metal atoms to store much more data on spinning disks than had ever been stored before, leading to vast innovations in the industry.
“The MP3 and iPod industry would not have existed without this discovery,” said Börje Johansson, a member of the Royal Swedish Academy which awarded the prize Oct. 11, according to The Associated Press. “You would not have an iPod without this effect.”
Fert, from the Université Paris-Sud in Orsay, France, and Grünberg, with the Institute of Solid State Research at the Jülich Research Center in Germany, will share the prize money.
Click here to read about how Georgia State University greatly improved its storage efficiency.
Fert, 69, and Grünberg, 68, were working independently in 1988 when they discovered the GMR effect, in which tiny changes in a magnetic field produce huge changes in electrical resistance.
“Youve leveraged a weak bit of magnetism into a robust bit of electricity,” Phillip Schewe, of the American Institute of Physics, told The New York Times.
The scanning heads in todays hard drives consist of alternating layers only a few atoms thick of a magnetic metal and a nonmagnetic metal. At that small size, quantum physics come into play, and new properties are suddenly available.
The GMR effect is an important asset to modern hard drives as they record data (text, audio, video and graphics) as a dense magnetic patchwork of zeros and ones, which is then scanned by a small head and converted to electrical signals that can be read onscreen.
“A long time ago, when we were just doing heads, wed read and write with an inductive head,” Mark Re, senior vice president of research at Seagate Technology—the worlds largest maker of disk drives—told eWEEK. “So you would have a magnetic core with some coils around it, and you would put a current into the coils to represent the data, and that would generate fields that would write on the disk.
“Then, when you pass the head over that information, the fields coming off the disk could get sent in the reverse direction. So the flux would go through the magnetic material and generate a current in the coil that you could read out.”
That took disk drives from the beginning (IBM invented them in 1953)to around 1990, Re said.
“Then, the industry separated the write and read head, so we still write inductively, meaning we pass a current through a coil and generate some fields; but now we read, starting back then, with something that was a sensing device whose resistance would change with field direction. And that was called magnetoresistance,” Re said.
That carried the industry for another period of time, Re said.
“Then in the late 80s, the two gentlemen (Grünberg and Fert) who won the Nobel Prize came up with an affect that was a little bit different, called giant magnetoresistance. Its basically a higher signal amplitude that you could get from this device,” he said.
Like most advancements in technology, there was a lot of practical work that had to be done to take this theory from the labs and get it working in devices, Re said.
“It became commercially available, oh, on the order of about 10 years after their discovery. That seems like a long time, but to go from a Nobel Prize-winning discovery to high-volume manufacturing within a decade is really pretty impressive,” Re said.
Fert and Grünberg did all the basic physics parts using thin-film iron—magnetic material—separated by chromium, which is nonmagnetic, Re said.
“When it actually got into the devices, it turned out to be different materials; so the first ones were nickel-iron alloy separated by copper. But the basic idea is what they came up with, and thats what the Nobel Prize celebrates,” Re said.
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