World's smallest magnetic data storage unit

World’s smallest magnetic data storage unit. It consists of just 12 iron atoms ordered in an anti-ferromagnetic structure (Photo: Sebastian Loth/CFEL)

Researchers at International Business Machines Corp. (IBM) create the world’s smallest magnetic data storage unit is made of just 12 atoms, a significant shrinkage in the world of information storage. They have stored and retrieved digital 1s and 0s from an array of just 12 atoms, pushing the boundaries of the magnetic storage of information to the edge of what is possible.

Traditional storage methods apparently need millions of atoms to storage the bits and bytes that make up our data. The new IBM breakthrough can store that data with only 12 little atoms needed. Until now, it was unclear how many (or how few) atoms would be needed to build a reliable, lasting memory bit, the basic piece of information that a computer understands. IBM has now found that magic number. The new technique uses ferromagnetism and might lead to smaller, faster, and more energy-efficient devices in the future.

The advance could lead to tiny hard drives able to store 200 to 300 times more information than they can today. Just imagine an iPod Touch that held 12.8 terabytes of music.

IBM’s 12-atom bit-keeper uses an antiferromagnetic structure, however, meaning that the atoms point in opposite directions. This keeps the atoms from interfering with each other, an important feature when you’re storing data just 12 atoms at a time. “In a ferromagnet all of these atoms add together to make a big spin and that big spin interacts with the neighboring big spin. And so you cannot control these independently anymore,” Heinrich says. “But in an antiferromagnet there is no big spin, and so you can put these guys very close together”

The team assembled the tiny hard drive from the atom up, using a special tool known as scanning tunneling microscope, or STM. They carefully placed atoms into rows of six atoms each. Two rows were enough to store one bit of information. Eight pairs of rows amounted to one byte of data.

Data was written into and read out of the bits using the STM, an impractical and slow method for manufacturing and the storage of the information — the magnetic state — is only stable at very cold temperatures, about 5 degrees above absolute zero. Warmer than that and the spins of the atoms get jostled. So it’s not like this type of bit will be integrated into hard disks anytime soon. Researchers said, ‘finding a material that works at room temperature isn’t impossible. What material will work, however, remains to be seen.’

But it answers some fundamental questions about the nature of classical mechanical systems, said Andreas Heinrich, the lead investigator into atomic storage at IBM Research.