13 September 2005
Nano-Diamonds Made Into Magnets
by Kate Melville
It's hard to think of an area of modern technology that doesn't utilize the effects of magnetism in some way. So it's no surprise that scientists get excited about magnets and possible applications for them on the nano-scale. And while magnetism is usually the preserve of metals, there is increasing interest in the prospect of creating metal-free magnets, particularly from carbon based materials. Carbon based magnets could offer substantial benefits over their metal counterparts, including stability, their low weight and low cost of production.
Now, in a paper in Physical Review Letters, researchers from the Rensselaer Polytechnic Institute report on a technique to make magnetic diamond particles only 4-5 nanometers across. These tiny magnets made from the crystalline form of carbon could find applications in fields ranging from medicine to quantum computing.
"Though the value of the magnetization is much lower than in regular magnets, the nature of the spin interactions in carbon could lead to a number of potential applications," said Pulickel Ajayan, co-author of the paper.
It is well known that defects and irregularities in pure carbon materials can give rise to electrons that are not paired with other electrons. Each unpaired electron produces a magnetic field by its spinning, and when all of the spins align, the material itself becomes magnetic. The researchers have developed a way to modify the structure of carbon in a controlled manner by firing clusters of atoms at the diamond particles. This produces magnetism at room temperature, and the total strength of the magnetism depends on the amount and type of atoms used.
The next step, said study lead-author Saikat Talapatra, is to calculate how the types of defects and their concentration in the pure carbon structure affect the magnitude of magnetism. "We are also working toward developing simpler ways to make magnetic nano-carbons in a more controlled fashion," he said. "The long-term goal is to show some real applications using these structures."
The researchers believe that magnetic nano-carbons could be the building blocks for the next generation of high-density memory devices. And because carbon materials are generally compatible with living tissue, these nanostructures could be useful in medical applications such as magnetic resonance imaging and the targeted delivery of drugs.
Source: Media release - Rensselaer Polytechnic Institute