Uncovering the Mysteries of a 'Strange Metal': Shedding Light on Y-Ball to Develop Quantum Technologies

Wednesday - May 3 2023, 16:17 UTC - 1 year ago

Y-ball, a mysterious class of 'strange metals' considered crucial for the development of advanced quantum materials, was probed experimentally by firing gamma rays at it using a synchrotron, which revealed unusual fluctuations in its electrical charge. Researchers at Rutgers University were able to explain this phenomenon by understanding how the electrons hop in and out of the atoms, causing their charge to fluctuate at a slow enough rate to be seen by Mossbauer spectroscopy.

Physicists at Rutgers University have offered theoretical perspectives on an experiment involving a "strange metal," which could play a crucial role in the development of future quantum technologies.

Researchers investigating a compound referred to as "Y-ball," which belongs to a mysterious class of "strange metals" considered crucial for the development of advanced quantum materials, have discovered novel methods for examining and comprehending its behavior.

The outcomes of the experiments may contribute to the creation of disruptive technologies and devices.

"It’s likely that quantum materials will drive the next generation of technology and that strange metals will be part of that story," said Piers Coleman, a Distinguished Professor at the Rutgers Center for Materials Theory in the Department of Physics and Astronomy at the Rutgers School of Arts and Sciences and one of the theoreticians involved in the study. "We know that strange metals like Y-ball exhibit properties that need to be understood to develop these future applications. We’re pretty sure that understanding this strange metal will give us new ideas and will help us design and discover new materials." .

Reporting in the journal Science, an international team of researchers from Rutgers, the University of Hyogo, and the University of Tokyo in Japan, the University of Cincinnati, and Johns Hopkins University described details of electron motion that provide new insight into the unusual electrical properties of Y-ball. The material, technically known as the compound YbAlB4, contains the elements ytterbium, aluminum, and boron. It was nicknamed "Y-ball" by the late Elihu Abrahams, founding director of the Rutgers Center for Materials Theory.

The experiment revealed unusual fluctuations in the strange metal’s electrical charge. The work is groundbreaking, the researchers said, because of the novel way the experimenters examined Y-ball, firing gamma rays at it using a synchrotron, a type of particle accelerator.

The Rutgers team – including Coleman, fellow physics professor Premala Chandra and former postdoctoral fellow Yashar Komijani (now an assistant professor at the University of Cincinnati) – have spent years exploring the mysteries of strange metals. They do so through the framework of quantum mechanics, the physical laws governing the realm of the ultra-small, home of the building blocks of nature such as electrons.

Analyzing the material using a technique known as Mossbauer spectroscopy, the scientists probed Y-ball with gamma rays, measuring the rate at which the strange metal’s electrical charge fluctuates. In a conventional metal, as they move, electrons hop in and out of the atoms, causing their electrical charge to fluctuate, but at a rate that is thousands of times too fast to be seen by Mossbauer spectroscopy. In this case, the change happened in a nanosecond, a billionth of a second.

"In the quantum world, a nanosecond is an eternity," said Komijani. "For a long time, we have been wondering why these fluctuations are actually so slow." "We reasoned," continued Chandra, "that each time an electron hops into a ytterbium atom, it stays there long enough to attract the surrounding atoms, causing them to move in and out. This synchronized dance of the electrons and atoms slows the whole process down, leading to slow fluctuations that we can actually detect." .