Virginia Tech nanoscientist seeks to develop thin films with a big payoff
Assistant Professor Satoru Emori seeks to use a $500,000 National Science Foundation CAREER Award to provide enhanced magnetic memory storage.
We keep much of our digital data in the “cloud” today. All those photos and videos are, at their core, zeros and ones stored on untold millions of magnetic tapes and discs.
These tapes and discs — though a vast improvement over the magnetic tape first used for computers in the 1950s — eat up a lot of energy, fast becoming a big part of the global energy problem. It’s a problem Satoru Emori, an assistant professor in the Virginia Tech Department of Physics, wants to solve. He’ll do this by creating new thin films made of specially engineered magnetic materials, a project funded by a five-year, $500,000 National Science Foundation CAREER award.
“In the long run, this research can help replace clunky magnetic tapes and disks with far more energy-efficient, and yet still economical, magnetic memories,” Emori said. “We’ll then be able to keep up with the growing demand for more information processing while reducing the global energy consumption.”
Emori is one of four Virginia Tech College of Science faculty members to recently earn the coveted CAREER grant, considered one of the most prestigious awards of its kind, that supports creative junior faculty who are expected to become future academic leaders. The other three are Frank Aylward of the Department of Biological Sciences, Lauren Childs of the Department of Mathematics, and Sujith Vijayan of the School of Neuroscience.
A member of the Virginia Tech community since 2017, Emori’s research focuses on “spintronics” and magnetic thin films. His Spin Magnetic Lab specializes in understanding the dynamics of magnetism in a variety of thin-film materials, essential for next-generation computing and communications technologies.
To record digital information, a memory device must switch between two states — those zeros and ones. In a magnetic memory, this means switching the direction of magnetism. Emori seeks to develop magnetic materials in which switching proceeds at a lower energy rate. To do this, he’ll “mix up” the chemical makeup of magnetic films, consisting of iron, nickel, and other transitional metal elements.
“Usually, such a magnetic film is made to be homogeneous. Its chemical composition is intended to be uniform throughout its thickness,” said Emori, an affiliated faculty member of both the College of Science’s nanoscience program, part of the Academy of Integrated Science, and the College of Engineering’s Department of Materials Science and Engineering. “But my proposed films are intentionally inhomogeneous. They have an intentional gradient or variation in chemical composition along the thickness.”
These proposed films are “vertically graded.” For example, a vertically graded iron-nickel film may be rich in iron on the bottom and rich in nickel at the top. The magnetic films will be about 10 nanometers thick, nearly 10,000 times thinner than a sheet of copy paper. According to Emori, a small number of academic papers have shown that vertically graded films may perform better than conventional magnetic films, especially in allowing for efficiently switching magnetic information by electrical means.
Early research success, headed by postdoctoral researcher Shuang Wu, now at Western Digital Corp., and physics graduate student Rachel Maizel, indicated that magnetism in vertically graded films can be rotated with low loss, showing promise for energy-efficient device applications.
However, such graded films have not been studied extensively.
“There’s a lot that remains to be understood about how chemical gradients actually affect the magnetic switching process,” Emori said. “This is where our research program comes in. We aim to understand the fundamental impact of chemical gradients on magnetic switching, and then leverage this basic scientific knowledge to improve the energy efficiency of information-technology devices.”