Several New Single-Molecule Magnets Discovered

Single-molecule magnets (SMMs) have many important advantages over conventional nanoscale magnetic particles composed of metals, metal alloys or metal oxides. These advantages include uniform size, solubility in organic solvents, and readily alterable peripheral ligands, among others.

Magnetic particles are how digital information is currently stored on hard drives, DVDs and other devices. There is great interest by high tech companies in increasing the density of information storage, which means increasing the number of bits of information in a given area of hard drive or other device. To get more digital information in a given area, each magnetic particle must be smaller. The size of the particles must also be the same so they will behave the same.

"Currently it is a problem to make really small, nanoscale magnetic particles from iron, iron oxide, or the other magnetic materials known to date," Christou said. "My group makes molecules containing the metal manganese. These molecules are much smaller than the magnetic particles currently used in information storage, but nevertheless are magnets at low temperatures. So each molecule can be considered an ultra-small magnetic particle, and this promises access to the ultimate high-density information storage devices."

IBM last year reported a new hard-drive record of 3 gigabits (3 billion bits) of digital information in one square centimeter of area using a known cobalt magnetic material. "The much smaller size of our molecules means we could get 30,000 billion of them into one square centimeter, and thus a storage density of 30,000 billion bits (or 30 terabits) is feasible. This is 10,000 times greater than the current best by IBM. The research challenge now is to find better SMMs that function at higher temperatures," Christou said.