International team finds unusual electrical behavior in material that holds promise for new technology
From: University of Cincinnati
March 13, 2023 -- Physicists
are learning more about the bizarre behavior of 'strange metals,' which operate
outside the normal rules of electricity.
Theoretical physicist
Yashar Komijani, an assistant professor at the University of Cincinnati,
contributed to an international experiment using a strange metal made from an
alloy of ytterbium, a rare earth metal. Physicists in a lab in Hyogo, Japan,
fired radioactive gamma rays at the strange metal to observe its unusual
electrical behavior.
Led by Hisao Kobayashi
with the University of Hyogo and RIKEN, the study was published in the journal Science.
The experiment revealed unusual fluctuations in the strange metal's electrical
charge.
"The idea is that
in a metal, you have a sea of electrons moving in the background on a lattice
of ions," Komijani said. "But a marvelous thing happens with quantum
mechanics. You can forget about the complications of the lattice of ions.
Instead, they behave as if they are in a vacuum."
Komijani for years has
been exploring the mysteries of strange metals in relation to quantum
mechanics.
"You can put
something in a black box and I can tell you a lot about what's inside it
without even looking at it just by measuring things like resistivity, heat
capacity and conductivity," he said.
"But when it comes
to strange metals, I have no idea why they are showing the behavior they do.
The mystery is what is happening inside this strange system. That is the
question."
Strange metals are of
interest to a wide range of physicists studying everything from particle
physics to quantum mechanics. One reason is because of their oddly high
conductivity, at least under extremely cold temperatures, which gives them
potential as superconductors for quantum computing.
"The thing that is
really exciting about these new results is that they provide a new insight into
the inner machinery of the strange metal," said study co-author Piers
Coleman, a distinguished professor at Rutgers University.
"These metals
provide the canvas for new forms of electronic matter -- especially exotic and
high temperature superconductivity," he said.
Coleman said it's too
soon to speculate about what new technologies strange metals might inspire.
"It is said that
after Michael Faraday discovered electromagnetism, the British Chancellor
William Gladstone asked what it would be good for," Coleman said.
"Faraday answered that while he didn't know, he was sure that one day the
government would tax it."
Faraday's discoveries
opened a world of innovation.
"We feel a bit the
same about the strange metal," Coleman said. "Metals play such a
central role today -- copper, the archetypal conventional metal, is in all
devices, all power lines, all around us."
Coleman said strange metals
one day could be just as ubiquitous in our technology.
The Japan experiment
was groundbreaking in part because of the way that researchers created the
gamma particles using a particle accelerator called a synchrotron.
"In Japan, they
use a synchrotron like they have at CERN [the European Organization for Nuclear
Research] that accelerates a proton and smashes it into a wall and it emits a
gamma ray," Komijani said. "So they have an on-demand source of gamma
rays without using radioactive material."
Researchers used
spectroscopy to study the effects of gamma rays on the strange metal.
Researchers also
examined the speed of the metal's electrical charge fluctuations, which take
just a nanosecond -- a billionth of a second. That might seem incredibly fast,
Komijani said.
"However, in the
quantum world, a nanosecond is an eternity," he said. "For a long
time we have been wondering why these fluctuations are actually so slow. We
came up with a theory with collaborators that there might be vibrations of the lattice
and indeed that was the case."
The study was funded in
part by the National Science Foundation and the Department of Energy.
https://www.sciencedaily.com/releases/2023/03/230313084546.htm
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