Creating the materials that drive technological innovation is a laborious process of discovery. From hundreds of thousands of possible combinations of elements, scientists choose one they suspect might have the properties they are looking for, figure out how to make it, and then run tests to see if it does what they want. More often than not, their initial suspicions turn out to be wrong. But with advances in computing power, a deeper understanding of physics, and the ability to manipulate individual atoms, scientists are beginning to design materials they know will have the desired properties.

Craig Fennie is working to make this materials-by-design concept a reality. By using first-principles quantum mechanical techniques he gains insight—not easily obtained through experimentation, if at all—into the physics of complex oxides in order to predict new properties.

Complex oxides are ubiquitous and include the most abundant mineral on earth, silicate perovskite. Their properties can vary tremendously depending on the charge, spin, and orbital ordering of their electrons, as well as the lattice structure of the crystal. “They are highly tunable and very unstable,” says Fennie, who worked at Argonne National Lab before coming to Cornell. “It’s one of the grand challenges of materials physics to first understand and then control the delicate balance among the interacting degrees of freedom prevalent in these compounds.”

Superconductivity, ferroelectricity, and magnetoelectricity are just three of the exotic properties of complex oxides. “To have all of these phenomena in a relatively similar family of compounds is utterly amazing,” says Fennie.

New complex oxides could yield multipurpose semiconductors for hard drives, sensors, and other applications. “I’m interested in tweaking complex oxides and seeing what new properties they can have,” says Fennie. “Imagine our semiconductors today. Replacing them with complex oxides with multiple functionalities could produce all sorts of interesting new electronic, magnetic, and optical devices.”

Materials-by-design could also help experimental scientists struggling to synthesize materials prone to defects. “We can come in and sort out the intrinsic properties of the materials which defects sometimes mask,” says Fennie.

Fennie was enticed to Cornell by the chance to work with big name experimentalists in the field like Darrell Schlom, who joined the Department of Materials Science in July from Penn State. “It’s a really dynamic group setting with these different communities—experimentalists, theorists, engineers—feeding off of each other,” says Fennie. “Cornell’s one of the few places where they really pride themselves on working together, and you can see that in all the multidisciplinary centers here. Working together scientists can solve these really, really challenging problems that will hopefully benefit society someday.” 

Craig Fennie's Web page