New findings are changing the way we think about superconductivity. Experiments at TU Wien (Vienna) underline the special role of immobile charge carriers, acting as a “glue”, which makes superconductivity possible.
Every standard cable, every wire, every electronic device has some electric resistance. There are, however, superconducting materials with the ability to conduct electrical current with a resistance of exactly zero – at least at very low temperatures. Finding a material which behaves as a superconductor at room temperature would be a scientific breakthrough of incredible conceptual and technological importance. It could lead to a wide range of new applications, from levitating trains to new imaging technologies for medicine.
The search for high-temperature superconductors is extremely difficult, because many of the quantum effects related to superconductivity are not yet well understood. Professor Neven Bariši?, professor for solid state physics at TU Wien (Vienna) is performing experiments with cuprates, a class of materials which behave as a superconductor at record temperatures as high as 140K at ambient pressure. Bariši? and his colleagues have now come up with a remarkable set of results and new insights that could profoundly change the way we think about these complex materials and high-temperature superconductivity in general.
The Quest for the Holy Grail
“The phenomenon of high-temperature superconductivity has been thoroughly investigated for decades, but nobody has cracked the problem yet”, says Neven Bariši?. “Quite a few materials show superconducting behaviour at temperatures close to absolute zero, and we understand why this happens in some of them. But the real challenge is to understand superconductivity in cuprates, where this states persists at much higher temperatures. A material which behaves as a superconductor at room temperature would be the Holy Grail of solid state physics – and we are getting closer and closer.”Bariši? and his colleagues have shown that there are two fundamentally different kinds of charge carriers in cuprates, and suggested that superconductivity crucially depends on the subtle interplay between them.
Some of the electrical charge is localized – each of these charge carriers sits at particular set of atoms and can only move away if the material is heated. Other charge carriers can move, jumping from one atom to another. It is the mobile charge that ultimately becomes superconductive, but superconductivity can only be explained by taking the immobile charge carriers into account too.
“There is interaction between the mobile and the immobile charge carriers, which governs the properties of the system”, says Bariši?. “Apparently, the immobile charges act as the glue, binding pairs of mobile charge carriers together, creating so-called Cooper pairs, which are the basic idea behind classical superconductors. Once paired the charge carriers can become superconducting and the material can transport the current with zero resistance.”
This means that in order to obtain superconductivity, there has to be a subtle balance of mobile and immobile charge carriers. If there are too few localized charge carriers, then there is not enough “glue” to pair the mobile charge carriers. If, on the other hand, there are too few mobile charge carriers, then there is nothing for the “glue” to pair. In either case, superconductivity is weakened or stops altogether. At optimal middle ground superconductivity persists at remarkably high temperatures. It was challenging to understand that the balance between mobile and immobile charges is changed, as a function of temperature or doping, in a gradual manner.
“We have performed many different experiments with cuprates, collecting large amounts of data. And finally, we can now propose a comprehensive phenomenological picture for superconductivity in cuprates”, says Neven Barisic. He has recently published his findings in several journals – most recently in ”Science Advances” – that demonstrate that superconductivity also appears in a gradual manner. This is an important step towards the goal of understanding cuprates and providing a way to search for new, even better superconductors.
If it became possible to create materials which remain superconductors even at room temperature, this would have far reaching consequences for technology. Electronic devices could be built that use hardly any energy at all. Levitating trains could be constructed, using extremely strong superconducting magnets, so that cheap, ultrafast transportation would become possible. “We are not yet near this goal”, says Neven Barisic. “But deep understanding of high-temperature superconductivity would pave the way to get there. And, I believe, that we have now taken several important steps in this direction.”
Learn more: Superconductors: Resistance is Futile
The Latest on: Superconductivity
via Google News
The Latest on: Superconductivity
- Science breakthrough: Researchers have just revealed a new state of matter - Cooper pairson November 18, 2019 at 10:44 am
These electron duos can both enable superconductivity and conduct electricity like existing metals. Cooper pairs are the electron duos allowing superconductors to conduct electricity without ...
- Inaugural IEEE International Conference on Quantum Computing and Engineering to Launch in 2020on November 14, 2019 at 4:22 pm
Positioned to be the ground-breaking quantum computing, engineering and technologies event of 2020, IEEE Quantum Week is sponsored by the IEEE Communications Society, IEEE Computer Society, IEEE ...
- New state of matter: A cooper pair metalon November 14, 2019 at 1:41 pm
In a finding that reveals an entirely new state of matter, research shows that Cooper pairs, electron duos that enable superconductivity, can also conduct electricity like normal metals do. For years, ...
- Thorium superconductivity: Scientists discover new high-temperature superconductoron November 7, 2019 at 7:59 am
The results of their study, supported by a Russian Science Foundation grant, were published in the journal Materials Today. A truly remarkable property of quantum materials, superconductivity is the ...
- Public lecture explores role of superconductors in energyon November 5, 2019 at 12:04 pm
Victoria University of Wellington will host a lecture by Dr Joseph Minervini, a global expert on superconductivity from Massachusetts Institute of Technology. Dr Minervini will discuss the role of ...
- High-temperature superconductivity in monolayer Bi 2 Sr 2 CaCu 2 O 8+on October 31, 2019 at 11:53 am
Mermin, N. D. & Wagner, H. Absence of ferromagnetism or antiferromagnetism in one- or two-dimensional isotropic Heisenberg models. Phys. Rev. Lett. 17, 1133–1136 (1966).
- A Physics Magic Trick: Take 2 Sheets of Carbon and Twiston October 31, 2019 at 6:16 am
Experiments by Dmitri Efetov and his colleagues show that this material can exhibit different electronic properties, including superconductivity.Credit...ICFO – The Institute of Photonic Sciences In ...
- Twisted Physics: Magic Angle Graphene Produces Switchable Patterns of Superconductivityon October 30, 2019 at 11:13 am
"It's kind of a holy grail of physics to create a material that has superconductivity at room temperature," University of Texas at Austin physicist Allan MacDonald said. "So that's part of the ...
- Twisted physics: Magic angle graphene produces switchable patterns of superconductivityon October 30, 2019 at 11:04 am
Now, a new study in the journal Nature by scientists from Spain, the U.S., China and Japan shows that superconductivity can be turned on or off with a small voltage change, increasing its usefulness ...
- Physicists Observe ‘Lazarus Superconductivity’ in Uranium Ditellurideon October 8, 2019 at 7:54 am
Physicists have observed a rare phenomenon called re-entrant superconductivity in uranium ditelluride (UTe 2). The discovery, reported in the journal Nature Physics, furthers the case for uranium ...
via Bing News