Harvard, BU Physicists Create New Tool to Probe High-Pressure Superconductors

Harvard and Boston University professors developed a tool that enables researchers everywhere to make measurements of different phenomena in high-pressure environments such as earthquakes, phase transitions, and superconductors.

Boston University Physics professor Chris R. Laumann ’03 first came up with the idea to integrate local sensors for high-pressure science, which helped spur the development of the tool, according to Harvard Physics professor Norman Y. Yao ’09.

Yao said in an interview that Laumann served as a mentor to him in graduate school and the two forged a longstanding professional relationship. Over the course of four years, they directed a team of researchers to create a tool for observing the behavior of high-pressure hydride superconductors.

Their motivation to develop the tool came from a struggle in experimental physics to observe properties of a sample subjected to extremely high pressure.

Usually, a sample is constrained and squished between two large chunks of diamond to create a high-pressure environment. However, because the sample is completely covered, scientists lack access to useful information such as magnetism and superconductivity.

Yao said the team was a “sprawling collaboration” of experts in topics that included superconductivity, high pressure science, superhard materials, and nitrogen-vacancy centers.

The project had to involve a lot of people “because there are many aspects that required understanding and finagling to get right,” Yao said.

The group’s solution to observe a sample’s properties in experimental physics was to “embed a very, very thin layer of sensors directly into the anvil that applies the pressure,” according to Yao.

The tool works at 100 gigapascals, 1,000,000 times the pressure of the atmosphere.

Laumann said that the new tool will allow researchers to measure magnetic, structural, and electrical properties with the “spatial resolution of the camera on your iPhone.”

The high-pressure sensors the team created could be used in the future to improve superconductors and characterize them better, but the timeline for that is uncertain.

“It’s a very, very slow process, but that’s how science works,” Yao said.

Cumrun Vafa, chair of Harvard’s Physics department, praised Yao as one of the department’s “young stars.”

Vafa said that a challenge for experimental physicists is determining how materials can become superconducting, and that Yao and Laumann’s recent work has helped to advance the field’s understanding of that.

He said it is unclear what their research will be used for in the future, and even its applications in terms of superconductors remain unknown.

“​​There are questions about what exactly we use this for but that usually comes naturally with any advance,” Vafa said. “We will find out in due course, but clearly being able to do such measurement is a good advance regardless.”