A TCD group is looking at the use of magnetic materials in an attempt to reduce computers to the size of a €2 coin, writes Dick Ahlstrom
Funny old thing, magnetism. Just when you think you understand what it is and what it can do, something new comes along. A Trinity College Dublin physicist has used it to levitate non-magnetic materials and to stop two liquids in a single container from mixing. Michael Coey, professor of experimental physics at Trinity's School of Physics, is used to being surprised by magnetic materials, having studied them for much of his professional research career.
Advanced magnetic materials have enabled us to pack 100 billion bits of computer information on a single square inch of computer storage space. They also look likely to produce the next generation of computers, systems that won't have to be reloaded with software every time you switch them on.
Coey is a leading international expert in magnetism and new magnetic materials. He is a foreign associate of the National Academy of Sciences in the US, a fellow of the Royal Society, and he won the Royal Irish Academy's inaugural gold medal in the physical and mathematical sciences last year. He is also a leading light in the development of a multi-purpose public science gallery in the building that will house Trinity's new Crann nanoscience research laboratories.
In recent years, Coey and his Science Foundation Ireland-funded research group have focused their efforts on "nanoscale magnetics and spin electronics".
"The broad question is what goes funny or what is different when we reduce our magnets to the 10-nanometre range," he says. A magnet that size is almost impossible to imagine. A human hair is 8,000 times thicker, according to Coey. And yet all modern computer magnetic memory is based on nanoscale magnetics, he says. It relies on magnetism and the building up of layers of thin films, some conductors, some insulators and some magnetic.
Spin electronics involves using the smallest natural magnets available, electrons.
"The idea of spin electronics is up to now we only made use of the electron's negative charge, while ignoring the fact that the electron is in itself a little magnet," Coey explains. "The big idea with spin electronics is to use the idea the electron is a little magnet and see what we can do with it."
His group studies new types of nanofilms, using unusual combinations to create novel magnetic effects.
"The concept is really very simple. The heart of the device is a sandwich with some magnetic layers and some space," Coey says. "But it has to be built on such a tiny scale."
The team's strength is its long experience with novel magnetic materials, an advantage when deciding which new combinations to try.
Coey believes that this technology will become at least as important to computing as semiconductors. The real breakthrough will come when second-generation nanomagnetic materials actually replace existing semiconductors to allow the production of magnetic transistors.
"What would be wonderful is if we had a magnetic semiconductor that could make spin transistors," he says.
His group has already developed unusual new magnetic materials using combinations that should not really be magnetic at all.
"We are very interested in a new group of materials which, to everybody's surprise, were ordinary oxides that when doped with feromagnetic material become magnetic at high temperatures. We don't understand why the magnetic interactions are so strong," he says.
Meanwhile, the group continues to study novel things about magnetic fields, such as the fact that non-magnetic materials can be made to "levitate" in a magnetic field when immersed in paramagnetic liquids.
Coey is also looking at the use of magnetic materials linked to biomolecules, which could be used in completely new medical imaging technologies.