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Photo of Samuel Marks
February 20, 2019

Saying ‘yes’ helps MS&E graduate student make his mark at Argonne National Laboratory

Written By: Sam Million-Weaver

Six months into a year-long fellowship at Argonne National Laboratory, materials science and engineering PhD student Samuel Marks’ research took an unexpected turn.

While developing new instrumentation to simultaneously image atomic structure and electronic properties in so-called correlated materials, Marks and colleagues discovered they could use the instrument to actually drive a transformation in what they were measuring.

And that means they now have a new way to manipulate a material while they measure the changes in real time. It’s an advance that will be useful for probing fundamental physical processes on the nanoscale in advanced electronic materials. Such materials could, for example, be used in more efficient electronics, photovoltaics or smart materials that respond to their environment.

The researchers weren’t expecting that a tiny probe could cause a big change in the material they were studying. The new instrumentation is a type of scanning probe microscope that detects subtle changes in the electric field between a probe tip and the sample to measure the carrier density near the sample’s surface. When the assay is coupled with x-ray nanodiffraction, a new technique emerges that provides researchers an unprecedented opportunity to simultaneously image a material’s crystal structure with its functional properties. “We didn’t know the material would respond in that way,” says Marks.

That startling result took Marks’ research in a different direction than he had anticipated when he applied for the fellowship that took him to Argonne’s Advanced Photon Source in Lemont, Illinois.

Yet Marks’ ability to roll with the punches is part of what motivated him to pursue a PhD in the first place.

“I’ve always been a ‘yes’ person,” says Marks who also received his bachelors of science degree from UW-Madison before returning for his PhD studies, “Whenever I start a new project, the more I learn, the more I want to keep going and discover an interesting material or find new properties.”

Now halfway through the third year of his doctoral degree, Marks, whose advisor is Materials Science and Engineering Professor Paul Evans, spent time at Argonne via a Department of Energy fellowship.

The fellowship places graduate students at national lab facilities and gives them the opportunity to work full time at DOE facilities, including high-powered X-ray sources called synchrotrons, which can be used for highly sensitive atomic-scale measurements.

At Argonne, Marks has been developing new microscopes to understand how the electronic properties of a material relate to its atomic structure—a bit of a departure from his thesis research at UW-Madison, which focuses on the synthesis and characterization of complex oxide materials.

In other words, Marks made materials at UW-Madison, whereas he’s making tools to understand those materials at Argonne. He anticipates being able to unify those two strands of research upon his return to Madison.

For now, though, Marks is taking full advantage of the facilities at Argonne and the unique working environment he’s found at a national lab.

“Working at a national lab is different from a university experience because you’re surrounded by people working on many different projects at very high levels,” says Marks. “Almost everyone can give you valuable insights about your research.”