PORTLAND, Ore. — Even the highest density hard-disk drives use approximately 1 million magnetic atoms to store a single bit of information. IBM's Almaden Research Center (San Jose, Calif.) has measured the ability to store a bit on a single atom, portending hard drives with ultra-high storage capacity.

Simultaneously, IBM's Zurich Research Lab has demonstrated a molecular switch that could replace current silicon-based chip technology with processors so small that a supercomputer could fit on a chip the size of a speck of dust.

IBM's claims its atomic-scale demonstration promises to pack up to 1,000 times as much information on a hard disk than current technologies. Such hard disks could store 30,000 full-length movies on a device the size of an iPod.

Most hard drive architectures use perpendicular recording, which depends on exotic new magnetic media. Magnetic anisotropy—a measurement of the ability of a media type to retain a bit—is the most important parameter for next generation perpendicular recording media.

"We have been able to measure the same property for a single magnetic atom," said Andreas Heinrich, manager of the scanning tunneling microscopy lab at IBM's Almaden Research Center. "We can literally take one atom, measure its magnetic anisotropy, put another atom next to it, see how that affects the [first atom's] magnetic anisotropy and from there learn how to develop a material with the ultra-high data storage densities we are predicting."

Artist rendering of two cross-shaped molecules that can be turned on (left) or off (right) by reorienting the two hydrogen atoms (white) in the center of the molecule.

Next, IBM researchers will measure the anisotropy of different types of atoms at room temperature to find a stable, ultra-dense material for use in commercial hard drives. "Our next step will be to find a material combination—a particular magnetic atom on a particular surface—that has the ability to stably maintain its magnetic orientation plus have be ability to switch between states so we can quickly flip its spin," said IBM scientist Cyrus Hirjibehedin. "We hope to be able to demonstrate such a stable media material within the next couple of years."

IBM meanwhile claims its molecular switch could replace today's semiconductors with devices smaller than those called for by the International Technology Roadmap for Semiconductors while exceeding the theoretical capabilities of CMOS chips.

"Since the invention of the semiconductor, we have relied on the ability to shrink their dimensions to improve performance," said Heinrich. "But the wavelength of an electron is about 10 nanometers, so you are never going to shrink semiconductors down to the size of single atoms which are only about 1 angstrom.

"So if you want to perform computations or data transmission at the atomic scale, you have to find an alternative to semiconductors. That is what the Zurich lab is doing—jumping ahead to design a new building block for molecular-sized circuits that could completely replace both silicon circuitry and copper wiring," Heinrich said.