Darrell Schlom makes sandwiches just a few atoms thick to feed science and technology's appetite for new materials.

Like most materials scientists, he used to take an experimental approach to cooking up new recipes. He'd combine a little of this with a little of that and then taste. But now Schlom makes sandwiches to order for Craig Fennie, another new Cornell Engineering faculty member. Fennie uses first-principles quantum mechanics to predict the properties of new materials before they've even been created. "I'm elated that Craig's here. He provides guidance," says Schlom. "I used to go on fishing expeditions. Now I have a map," he adds, laughing.

The ingredients in Schlom's sandwiches are complex oxides, the properties of which vary tremendously depending on the charge, spin, and orbital ordering of electrons, as well as crystal structure. "Craig has these wacky ideas like 'Arrange these atoms in this particular new way that they don't normally arrange in,'" says Schlom. "And he has crazy predictions that go along with this, like 'If you can do this, it should be simultaneously ferroelectric and ferromagnetic.' You hear the prediction, and you go, 'How could it possibly be true?'"

While knowing the ingredients and how they should be layered cuts out the guess work, figuring out how to actually put the sandwich together still takes time. "It's a big challenge. After about two years we either give up totally, or we succeed," says Schlom. "For all of his predictions that we've tested, he's got a 100 percent batting average, which has really given me a lot of faith in the relatively new materials-by-design approach that brave theorists like Craig have been boasting about."

To apply materials by design to a wider variety of phenomena like superconductivity, Shlom and Craig work with other Cornell theorists including Eun-Ah Kim and Richard Hennig. Too many cooks don't spoil these sandwiches.

Schlom uses molecular-beam epitaxy to make his sandwiches. The technique requires an ultra high vacuum which allows single "beams" of ultra pure elements to slowly deposit in a film that takes on the crystalline structure of whatever substrate it is grown on. "We're laying down one sheet of atoms at a time," he says. "It's atomic spray painting."

Once Schlom thinks he has created the sandwich Fennie ordered, he sends it off for testing to see if it really is and if the new sandwich is as tasty as Fennie predicted. Many of the researchers who do that work—David Muller, Joel Brock, Kyle Shen, and Seamus Davis—are right here on campus. "That's part of the reason I'm so excited to be here," says Schlom. "These folks are all number one in their fields, so it's like playing on the dream team."

Complex oxides are already fueling technological innovation. Used as an insulator in the latest transistors, hafnium oxide has enabled the creation of smaller computer chips that run faster yet drain laptop batteries more slowly. Schlom received the 2008 Materials Research Society Medal for work he did at Penn State showing that hafnium oxide was relevant for this application. "Nobody noticed our work for five years. It was just like a boat anchor," says Schlom, laughing.

But by 1999, the computer chip industry totally revised its list of insulating materials that might work to be those Schlom had calculated would not react with the silicon used in transistors. "Our work went from total obscurity to being what rewrote the guidelines of what to look for. And hafnium oxide was one of the materials that we suggested," says Schlom. "That's the beauty of fundamental science. It can become important in ways you never expected."

Prof. Schlom's Web site