Single-atom magnets store bits of data

NEW ORLEANS — ­The tiniest electronic gadgets have nothing on a new data-storage device. Each bit is encoded using the magnetic field of a single atom — making for extremely compact data storage, although researchers have stored only two bits of data so far.

“If you can make your bit smaller, you can store more information,” physicist Fabian Natterer of the École Polytechnique Fédérale de Lausanne in Switzerland said March 16 at a meeting of the American Physical Society. Natterer and colleagues also reported the result in the March 9 Nature.
Natterer and colleagues created the minuscule magnetic bits using atoms of holmium deposited on a surface of magnesium oxide. The direction of each atom’s magnetic field served as the 1 or 0 of a bit, depending on whether its north pole was pointing up or down.

Using a scanning tunneling microscope, the scientists could flip an atom’s magnetic orientation to switch a bit from 0 to 1. To read out the data, the researchers measured the current running through the atom, which depends on the magnetic field’s orientation. To ensure that the change in current observed after flipping a bit was due to a reorientation of the atom’s magnetic field, the team added bystander iron atoms to the mix and measured how the holmium atoms’ magnetic fields affected the iron atoms.

The work could lead to new hard drives that store data at much greater densities than currently possible. Today’s technologies require 10,000 atoms or more to store a single bit of information.

Natterer also hopes to use these mini magnets to construct materials with fine-tuned magnetic properties, building substances a single atom at a time. “You can play with them. It’s like Lego,” he says.