STOCKHOLM France's Albert Fert and Germany's Peter Gruenberg won the 2007 Nobel Prize for physics on Tuesday for a breakthrough in nanotechnology that lets huge amounts of data be squeezed into ever-smaller spaces.
Gadgets from powerful laptops to iPods owe their existence to the discovery.
The 10-million Swedish crown (756,000 pound) prize, awarded by The Royal Swedish Academy of Sciences, recognised the pair for revealing a physical effect called giant magnetoresistance.
"It is thanks to this technology that it has been possible to miniaturise hard disks so radically in recent years," the academy said in a statement.
Giant magnetoresistance -- GMR for short -- works through a large electrical response to a tiny magnetic input.
When atoms are laid down on a hard disk in ultra-thin layers, they interact differently than when spread out more. This makes it possible to pack more data on disks.
Surrounded by journalists in Paris soon after learning of his award, the 69-year-old Fert started chatting with some youngsters near the CNRS research centre he co-founded.
"You like physics?" he asked, telling them he had just won the Nobel prize. "If you are able to listen to music on your MP3 player, it is a bit thanks to what I've done."
Fert and Gruenberg, 68, figured out how to stack nanometre-thin layers of magnetic and non-magnetic atoms to produce the GMR effect.
"The story of the GMR effect is a very good demonstration of how a totally unexpected scientific discovery can give rise to completely new technologies and commercial products," the Nobel committee wrote.
It works because of a property called spin. Electrons -- the charged particles within atoms -- "spin" in different directions under various circumstances, producing the changes in resistance that are used to store data.
"It is the thing that has made iPods possible and anything that requires lots of data storage, like YouTube," said Chris Marrows, a physicist at Leeds University who specialises in a branch of technology known as spintronics.
Thanks to advances based on GMR, a typical laptop computer now holds about 100 gigabytes of data. That is equal to the information contained in a kilometre-long (3,280-foot) bookshelf, roughly an entire library floor of academic journals.
Ben Murdin, a physics professor at the University of Surrey in southeast England, described the technology as something practically out of a work of science fiction.
"A computer hard disk reader that uses a GMR sensor is equivalent to a jet flying at a speed of 30,000 kilometres (19,500 miles) per hour ... at a height of just one metre above the ground, and yet being able to see and catalogue every single blade of grass it passes over," Murdin said.
Fert and Gruenberg each made the discovery independently of the other. They shared the 2007 Japan Prize for their work.
As Nobel physics laureates, the two join the ranks of some of the greatest names in science, including Albert Einstein, Marie Curie, Niels Bohr and Wilhelm Rontgen. Rontgen won the first prize in 1901 for discovering X-rays.
Gruenberg said the award was "slightly" expected. "But not completely because then I would have worn a tie," he told reporters, sporting an open-neck shirt. "What is my first reaction? Well, I can't remember, I was stunned."
German Chancellor Angela Merkel, a physicist herself, said: "It is a great honour ... The prize shows how fundamental research can lead to technical, practical uses."
Merkel's French counterpart, President Nicolas Sarkozy, portrayed the award as a coup for Europe.
"It is European research which is crowned," Sarkozy said in a statement. He said Fert was among the great minds who led the way forward for French development and glory.
This was the second of this year's crop of Nobel prizes, which are handed out annually for achievements in science, literature, economics and peace.
All but one of the prizes were established in the will of 19th century dynamite millionaire Alfred Nobel. The economics award was established by Sweden's central bank in 1968.
(Additional reporting by Maggie Fox in Washington, Simon Johnson, Sarah Edmonds, and Emma Bengtsson in Stockholm, and Michael Kahn in London and Thierry Leveque in Paris)