NEW YORK, Sept. 22 (UPI) -- Magnetic diamonds roughly five nanometers across might find use in everything from medicine to computers, experts told UPI's Nano World.
Magnetic nanoparticles are routinely used to boost the resolution of magnetic resonance imaging scans when injected into the body. In addition, scientists are experimenting with magnetic nanoparticles as construction blocks for computer memory and quantum computers, materials physicist Saikat Talapatra at the Rensselaer Polytechnic Institute said.
Magnetic nanoparticles are typically made of metals, but increasingly scientists are researching metal-free versions. "If you want to buy cobalt or nickel nanoparticles, they would probably cost more than carbon," Talapatra said. "Carbon is lightweight and very cheap as a starting material."
Molecular defects and irregularities in carbon molecules can give rise to electrons that are not paired with other electrons. Each unpaired electron produces a magnetic field when it spins. When all these spins align, the material becomes magnetic.
The first magnetic carbon nanoparticles were reported in 2001 from Russian physicist Tatiana Makarova and her colleagues. They were made from soccer-ball-shaped carbon molecules known as buckminsterfullerenes or buckyballs, which are quite expensive. Talapatra and his colleagues wanted instead to create magnetic carbon nanoparticles made of diamond or graphite.
"Commercially available nano-diamonds are very cheap, actually," Talapatra said.
Talapatra and his colleagues devised a way to tinker with the molecular structure of carbon in a controlled manner by firing carbon or nitrogen ions at it. In findings appearing in the journal Physical Review Letters, they describe nanometer-scale diamonds and graphite they created that are magnetic at room temperature. The resulting strength of the magnetism depends on the amount and type of ions used.
Magnetic carbon is less magnetic than regular magnets, but Talapatra said they could still prove useful in electronic and medical applications. For instance, carbon is generally compatible with living tissue. Magnetic carbon nanoparticles with drugs attached to them could therefore be used to help deliver medicines to specific parts of the body by steering them with a magnet from the outside, Talapatra explained.
Talapatra said the next step is to experiment with implanting other kinds of ions, as well as calculating how the types of defects and their concentration in the carbon affect the magnitude of magnetism. "We are also working toward developing simpler ways to make magnetic nano-carbons in a more controlled fashion," Talapatra said, such as laser heating or high vacuum annealing.
"They do have something interesting in their hands," said theoretical physicist David Tomanek of Michigan State University in East Lansing. Future experiments may want to analyze what temperatures the magnetic diamonds and graphite lose their magnetism at, he added.
