The U.S. Department of Energy (DOE) is funding cutting-edge research into new magnetic materials and the theory of spinning electrons that could lead to better data storage and processing and more efficient magnetic resonance imaging (MRI) for radiologists, and it may even have implications for quantum computing. MU physics professors David Singh and Carsten Ullrich were recently informed they have won DOE grants to pursue their research.
Frontiers in Magnetic Materials
Singh calls magnetism one of the most remarkable and diverse properties of matter.
“Without magnetism, our motors don’t work, our computer storages don’t work—it’s everywhere in technology,” he says. “That, in part, is the DOE’s interest in this. The DOE is also interested in ‘blue sky’ kinds of topics—open-ended research where we are not quite sure what the eventual technological impact will be, but it could be very big.”
Singh is studying unusual forms of magnetism that he says could be useful in new superconductors, which could allow MRI machines to operate at higher temperatures or under higher magnetic fields, leading to better image resolution. Singh says his research may also have implications for technologies that are not yet mature such as quantum computing.
“One of the topics I intend to investigate under this grant is unconventional superconductivity with magnetism as an underlying driving force for this superconductivity,” he says. “If that is successful, we may discover new superconducting materials that have the right properties to be the basis of a quantum computer, and a quantum computer could do things like break codes we think are secure or solve problems we currently can’t solve with the computers we have.”
Singh says one of the properties of superconducting material is that a current can flow without resistance. There are two classes of superconductors—conventional, such as the ones that currently provide the big magnetic fields needed for MRIs to work, and unconventional, which Singh says may have properties that are much better than what is currently available. He says it is widely believed that magnetism is responsible for unconventional superconductors, an idea the grant will allow him to explore.
“I’m excited about this grant from DOE because it allows us to do forefront research involving graduate students and postdocs in my group, and to make a difference by maybe discovering exciting new magnetic materials that open up new scientific directions and or impact technology,” Singh says.
Ullrich is a theoretical physicist who studies the behavior of electrons. An electron is a stable subatomic particle with a charge of negative electricity, which is found in all atoms and acts as the primary carrier of electricity in solids. An electron is the smallest unit of electricity, which powers the world we live in.
“An electron has an electric charge, but it also has a property called the spin—visualize the electron as a little blob of charge like a tiny marble that zips around in a metal and spins about on its own axis,” Ullrich says. “Electrons have these two properties—the charge and the spin, and in ordinary computers nobody cares about the spin, it’s just not used. It’s just the electric charge that matters, but spintronics says ‘What about this other property of electrons?’” Spintronics is the study of the spin of the electron and its associated magnetic moment.
In computation and data storage, information is digitized into bits—ones and zeroes, which can be stored and manipulated in various ways. Similarly, the spin of an electron can point up or down and can be switched or flipped. Ullrich is developing methods for using spintronics to encode information. “Can we build things like faster transistors, or qubits (the basic unit of quantum information) for quantum information that take advantage of the fact that electrons also carry spin?”
Ullrich says he works with pencil and paper or at his computer trying to understand the behavior of electrons in groups. He uses the analogy of a crowd of people at a football stadium to explain the concept.
“What happens if you bring 100,000 people together in a stadium? They are all sitting quietly or they get excited and worked up like when they do the wave,” he says. “It turns out electrons can do similar things—they can just sit there quietly or they can form these waves that travel around.”
Ullrich says it is impossible to predict the behavior of individual electrons, so he uses a method called density functional theory.
“You could ask each individual in the stadium how they interact with all other individuals, but you would need to know a vast amount of information,” he says. “Rather, if you want to know what happens in one part of the stadium, you describe it with the average behavior of the crowd. That’s how we treat complicated materials—we don’t look at each and every electron individually, we describe it under the influence of an average effect coming from all others. To find what that average behavior is, you have to find a theory that tells you how to do it, and that theory will involve some assumptions and approximations. What we are trying to do is to make better assumptions and approximations so our results are better.” He says this theory will allow researchers to predict how the wave-like behavior of the electronic spins can transmit information, and to develop faster techniques for data storage and manipulation.
By Jordan Yount