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The Student News Site of Stony Brook University

The Statesman

The Student News Site of Stony Brook University

The Statesman


Under the Microscope: Quantum fluctuations in an unconventional superconductor at SBU

Every other week, Ricardo Raudales, a Ph.D. candidate at Stony Brook University’s Department of Neurobiology and Behavior, will take a look at Stony Brook-related science and research news.

While temperatures have started to drop on campus, they are nowhere near those being achieved in one professor’s laboratory. To probe the quantum transformations undergone by matter, Brookhaven physicist and Stony Brook professor Meigan Aronson is getting down to near absolute zero–a mere 0.06 Kelvin. At these temperatures, even matter as we know it starts to get dicey.

For reference, average room temperature is about 298 Kelvin.

“Under these cold conditions, the electronic, magnetic, and thermodynamic performance of metallic materials is defined by these elusive quantum fluctuations,” Aronson said in a press release. “For the first time, we have a picture of one of the most fundamental electron states without ambient heat obscuring or complicating those properties.”

To study these fluctuations in near-absolute zero conditions, the researchers could not use just any metallic material.  They had to rely on a metal compound composed of yttrium, iron and aluminum (YFe2Al10), which they previously discovered while researching superconductors.

YFe2Al10 forms a rare crystal structure consisting of two-dimensional layers. This inherent layering is what enabled the physicists to manipulate its ferromagnetic properties.

In ferromagnetism, certain metals can act as permanent magnets due to long-range ordering of electron spin at the atomic level. It is this phenomenon that is responsible for everyday magnets, including those found on your fridge. 

Unlike household magnets, YFe2Al10 was shown to exhibit ferromagnetism exactly at absolute zero. Above this temperature, the material suddenly loses its ferromagnetic properties. The researchers could switch on or off the compound’s ferromagnetism by simply altering the temperature or applying a magnetic field.

By modeling how these fluctuations varied in space and time, the researchers could get a better sense of how a compound might alternate between superconductive and ferromagnetic states.

“Robust magnetic ordering generally blocks superconductivity, but suppressing this state might achieve the exact balance of quantum fluctuations needed to realize unconventional superconductivity,” physicist Alexei Tsvelik said. “It is a matter of great experimental and theoretical interest to isolate these competing quantum interactions that favor magnetism in one case and superconductivity on the other.”

Though more research is needed, the potential applications for such a material already exist. Today, superconductors are used in everything from electric motors and MRI machines to high-speed maglev trains. The precise control that might be afforded by materials like YFe2Al10 could help overcome engineering obstacles and lead to advances in many sectors.

The next steps will involve modifying YFe2Al10 in the hope of developing superconductive materials that can become ferromagnetic at higher temperatures. Ultimately, this could open up a host of new technologies designed around these unconventional superconductors.

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