Electron family creates previously unknown state of matter

Date:
November 5, 2021
Source:
Technische Universita"t Dresden
Summary:
Researchers have demonstrated a completely novel state of matter
in a metal. It is created by the combination of four electrons --
until now, only electron pairs were known. This discovery could
lead to a new type of superconductivity, an entirely new research
direction, and revolutionary technologies such as quantum sensors.



FULL STORY ==========================================================================
An international research team from the Cluster of Excellence ct.qmat- Complexity and Topology in Quantum Matter has demonstrated a completely
novel state of matter in a metal. It is created by the combination of
four electrons- until now, only electron pairs were known. This discovery
could lead to a new type of superconductivity, an entirely new research direction, and revolutionary technologies such as quantum sensors. The
results have now been published in the journal Nature Physics.


========================================================================== Dissipationless electric energy transport -- also known as
superconductivity - - is seen as a beacon of hope for the energy
industry. Since its discovery more than 100 years ago, scientists
around the world have been investigating this well-known quantum
phenomenon, which, however, requires the electrons in metals to be
cooled to ultra-low temperatures. A team of scientists from the Cluster
of Excellence ct.qmat-Complexity and Topology in Quantum Matterat the Universities of Dresden and Wu"rzburg has now made a remarkable discovery:
In certain superconducting metals, a compound of four electrons ensures
that a completely new state of matter is created. Until now, only electron pairs were known to play a role in superconductivity. The discovery by the research team led by Prof. Hans-Henning Klauss of Technische Universita"t Dresden is therefore considered a milestone for materials research. The research results have been published in the journal Nature Physics.

Electron family surprises researchers In quantum physics,
superconductivity, discovered as early as in 1911, is probably the
best-known phenomenon to date. Its theoretical foundations are understood
since the 1950s. It is essential that electrons at ultra-low temperatures
no longer move through a metal individually, but as pairs.

Electron pairs do not collide with the atomic lattice, so that they can transport their charge without any loss of energy.

When the Dresden researchers led by Henning Klauss experimentally
investigated the superconducting metal Ba1-xKxFe2As2 from the class of
iron pnictides, they initially suspected a mistake: "When we discovered
that suddenly four electrons instead of two were forming a bond, we
first believed it was a measurement error. But the more methods we used
to confirm the result, the clearer it became that this had to be a new phenomenon: all data are consistent with the same result. Now we know that
the four particle electron family in certain metals creates a completely
new state of matter when cooled to ultra-low temperatures. What this
will lead to in the future will become clear over the next few years,"
comments Dresden physicist Hans-Henning Klauss.

Results tested for more than two years Already about ten years ago,
it was theoretically predicted that there could be an unusual state of
matter in certain superconducting metals, in which four instead of two electrons play a role. The international research team of the Cluster
of Excellence ct.qmat has now provided the first experimental evidence.

It was scrutinized for two years using seven different methods.



==========================================================================
"We first discovered the new state of matter in a Swiss particle
accelerator.

We were then able to confirm our results with six other methods on site
in Dresden and at Stockholm University. The great location advantage of
Dresden is the short distances: I can bring my sample almost on foot to
a Leibniz Institute or Helmholz Center," emphasizes the project's lead experimenter, Dr.

Vadim Grinenko of TU Dresden. The theoretical interpretation of the
measurement results comes from the Swedish physicist Prof. Egor Babaev.

New type of superconductivity possible The discovery of iron pnictides
as a class of materials particularly suitable for superconductivity
already triggered a worldwide research boom in physics and materials
science starting in 2008. The energy industry has high hopes for the
popular quantum phenomenon because up to 15 percent of energy is lost in conventional energy transport due to transport resistance. "If you could actually transport electricity across the country in superconducting
metals at room temperature, about ten large power plants would be
superfluous right away," says Klauss. However, basic research -- such as
Prof. Klauss' -- is concerned with understanding the underlying physics
and can at best speculate about future applications.

"One can assume that our results will lead to a whole new line of
research, looking for other metals with four connected electrons, for
example, or exploring how materials need to be changed to create an
electron family," Klauss explains. "In purely theoretical terms, a whole
new type of superconductivity would also be possible with our electron
family. The only thing that is certain is that iron pnictides are well
suited for technologies such as quantum sensors due to their new aggregate state." International participation In addition to Prof. Hans-Henning
Klauss, Dr. Vadim Grinenko of TU Dresden and Prof. Egor Babaev of the
Royal Institute of Technology in Stockholm were significantly involved
in the current research findings. The experiments were carried out at
the Swiss Paul Scherrer Institute in Villigen as well as at the Leibniz Institute for Solid State and Materials Research in Dresden, the high-
field magnet laboratory of the Helmholtz Center Dresden-Rossendorf and
the AIST Institute in Tsukuba in Japan.

========================================================================== Story Source: Materials provided by Technische_Universita"t_Dresden. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Vadim Grinenko, Daniel Weston, Federico Caglieris, Christoph Wuttke,
Christian Hess, Tino Gottschall, Ilaria Maccari, Denis Gorbunov,
Sergei Zherlitsyn, Jochen Wosnitza, Andreas Rydh, Kunihiro Kihou,
Chul-Ho Lee, Rajib Sarkar, Shanu Dengre, Julien Garaud, Aliaksei
Charnukha, Ruben Hu"hne, Kornelius Nielsch, Bernd Bu"chner,
Hans-Henning Klauss, Egor Babaev. State with spontaneously
broken time-reversal symmetry above the superconducting phase
transition. Nature Physics, 2021; DOI: 10.1038/ s41567-021-01350-9 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211105134634.htm

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