Magnetic materials of the future
Some 80 percent of all the information in the world is stored on magnetic media, such as computers, mobile phones, and digital cameras. But access to raw materials may present a problem in the future. Moreover, there is a need for ever-greater storage capacity and less energy consumption. Olle Eriksson is the researcher who is trying to predict the magnetic materials of the future.
High up under the rafters of Ångström Laboratory, Olle Eriksson has a view of the city of Uppsala. But more often he inspects the world at the level of the atom. This is one of the world’s premier environments in materials theory, with a worldwide network and about 100 collaborative partners. With the aid of mathematical models and computer simulations, scientists here are studying magnetic materials, for example, in order to theoretically predict properties such as magnetic hardness and magnetization dynamics.
Currently magnetic materials with great hardness are based on rare earth metals, such as neodymium. About 90 percent of all mines with such metals are in China, and prices are skyrocketing. Access to raw materials can present a problem in the future.
“That’s why we have to find new metal combinations. We can perform theoretical calculations with very great precision and execute searches faster than one can experimentally. We hope our research will lead to materials with equivalent properties and even better materials,” says Olle Eriksson.
Database with pattern recognition
Suitable candidate materials are being prospected with the aid of pattern recognition. These Uppsala scientists have created a database with the electron structures of materials.
“We look a lot at how the electrons move in the material. It’s electron movements that create all the chemical bonds that stabilize materials. This explains why iron is magnetic, why windows are transparent, and why our DNA strands look the way they do, to take just a couple of examples,” Olle Eriksson explains.
The electronic structure determines the properties of the material. Now Olle Eriksson and his associates have calculated the electron structure of more than 100,000 materials, such as iron, aluminum, and silicon, and they have made their data available on their homepage, accessible to everyone.
Materials can be invented theoretically on computers and then tested experimentally. This speeds up research and makes the work more reliable. Some metals are more suitable than others for magnetic memories.
“For instance, we’ve developed an iron-cobalt alloy that we believe will have good properties. This was verified by another research group here at Ångström Laboratory that was able to produce the material in thin films. But now we want to be able to recreate the properties of the material in bulk form, and we’ll be collaborating with chemists here in this same building,” says Olle Eriksson.
Designing new superconductors
Electron structure is also of fundamental importance when it comes to understanding properties of materials such as superconductors. In superconductors, current flows with no electrical resistance. If superconductors could function in room temperature, we would have the solution to the world’s energy problems and a platform for a host of applications that sound like science fiction today: levitating trains, high-tension wires with no power losses, and a new generation of tremendously powerful computers.
Olle Eriksson, together with his colleague Mattias Klintenberg, recently created a list of more than a hundred materials that are potential new high-temperature superconductors. Thousands of scientific articles have been written about this phenomenon since the breakthrough in 1986, but the underlying mechanisms remain unknown.
“We’ve discovered a few things that stand out and are common to the electron structure of these materials. Now as we go through our database, we’re able to draw up a list of new candidates. It’s an elusive and exciting subject, trying to solve the riddles of superconductivity. Lots of people have scratched their heads and given up, so it would be incredible if this were to lead to a new breakthrough.”
In the past, technology could not deal with pattern recognition. But now computers are fast enough and the software advanced enough for us to bring out the detailed structure needed, and this can be the platform that allows us to discover these sought-after materials.
Pieces of the puzzle that explain reality
It wasn’t self-evident that Olle Eriksson would become a theoretical physicist, but his interest was aroused in high school. At Uppsala University he was fortunate to do his doctoral work with Börje Johansson, well known as a member of the Nobel Prize Committee for Physics, for example. Johansson has been an inspiring role model and a close colleague. Olle Eriksson has also worked at Los Alamos in the US, with three years as a postdoc and one year as a visiting researcher.
“It’s a fantastic research environment, but the environment here at Uppsala is much better than what they can put together there.”
Research findings over the next few years will lead to faster, more energy-efficient, and better computers. Such applications are great, but basic research is also rewarding.
“It’s fun for us to build models that we believe describe reality and then to have the models verified in experiments. That gives us yet another piece of the puzzle for us to put in place to help us understand how reality is structured.”
Nils Johan Tjärnlund
Translation Donald S. MacQueen