Physicists at the University of Leipzig have once again gained a deeper understanding of the mechanism behind superconductors. This brings the research group led by Professor Jürgen Hass a step closer to their goal of developing the foundations of a theory of superconductors that allow current to flow without resistance and without energy loss. The researchers found that in the superconducting copper-oxygen bonds, called cuprates, there should be a very specific charge distribution between the copper and oxygen, even under pressure.
This confirmed their findings in 2016, when Haas and his team developed an experimental magnetic resonance-based method that could measure superconductivity-related changes in the structure of materials. They were the first team in the world to identify a measurable material parameter that predicts the maximum possible transition temperature – a condition required to achieve superconductivity at room temperature. They have now discovered that cuprates, which promote superconductivity under pressure, follow the charge distribution expected in 2016. The researchers have published their new findings in the journal PNAS.
“The fact that the transition temperature of coppers can be improved under pressure has puzzled researchers for 30 years. But until now we didn’t know the mechanism responsible,” Haas said. He and his colleagues at the Felix Bloch Institute for Solid State Physics have come very close to understanding the actual mechanism of these materials. “At the University of Leipzig – with the support of the Graduate School Building with Molecules and Nanobjects (BuildMoNa) – we created the necessary prerequisites for research into cuprates using nuclear resonance, and Michael Gurkutat was the first PhD researcher to join us. Together, we established the Leipzig relation, which states that we must “You have to take electrons away from the oxygen in these materials and give them to the copper in order to increase the transition temperature. You can do this with chemistry, but also with pressure. It never occurred to anyone that we could measure all this with nuclear resonance.”
Their current research discovery may be exactly what is needed to produce a room-temperature superconductor, which has been the dream of many physicists for decades and is now expected to take only a few more years, according to Haase. Until now, this was only possible at very low temperatures of minus 150 degrees Celsius and below, which are hard to find anywhere on Earth. About a year ago, a Canadian research group verified findings by Professor Haas’ team from 2016 using newly developed computer-assisted calculations, thus backing up the findings theoretically.
Superconductivity is already used today in many ways, for example, in magnets for MRI machines and in nuclear fusion. But it would be much easier and less expensive if superconductors were operated at room temperature. The phenomenon of superconductivity in metals had been discovered since 1911, but not even Albert Einstein attempted to come up with an explanation at that time. Almost half a century passed before BCS theory provided an understanding of superconductivity in metals in 1957. In 1986, the discovery of superconductivity in ceramic materials (copper superconductors) at much higher temperatures by physicists Georg Bednors and Karl Alexander Müller raised new questions , but also raised hopes that superconductivity could be achieved at room temperature.