Understanding High Temperature Superconductivity Using Ultra Low Temperature

2 Si 2 And the figure of the cryostat used for the measurement. Credit: Vienna University of Technology “width =” 800 “height =” 530 “/>

Crystal structure of “strange metal” superconductor YbRh2Si2 Diagram of the cryostat used for the measurement.Credit: Vienna University of Technology

Amazing discoveries at the Vienna University of Technology can help solve the mystery of high-temperature superconductivity. The famous “strange metal” turned out to be a superconductor.

so low temperature, identification material Lose them Electrical resistance This superconducting phenomenon has been known since 1911, but it is not yet fully understood. And that’s a shame. Because finding a material that can maintain superconducting properties at high temperatures will probably revolutionize the technology.

The discoveries made at the Vienna University of Technology (Vienna) could be an important step in this direction. A team of solid-state physicists has studied so-called “strange” and unusual substances. metal“Made of ytterbium, rhodium, and silicon. Strange metals show an unusual relationship between electrical resistance. temperature.. For this material, this correlation is found over a particularly wide temperature range, and the underlying mechanism is known. Contrary to previous assumptions, this material is also a superconductor, and it has been found that superconductivity is closely related to strange metal behavior.This may be the key to understanding High temperature superconductivity The same is true for other classes of materials.

Strange metal: linear relationship between resistance and temperature

For ordinary metals, the electrical resistance at low temperatures increases in proportion to the square of the temperature.Several High temperature superconductorHowever, the situation is quite different. At low temperatures, below the so-called superconducting transition temperature, no electrical resistance is shown, and above this temperature, resistance increases linearly with temperature rather than quadratic. This is what defines “strange metal”.

“Therefore, in recent years it has already been suspected that this linear relationship between resistance and temperature is very important for superconductivity,” said Silke Bühler Passchen, who heads the research area “Quantum Materials” at the Institute of Solid State Physics. The professor says. TU in Vienna. “But unfortunately, until now we did not know the right material to study this in depth.” For high-temperature superconductors, the linear relationship between temperature and resistance is usually only in a relatively narrow temperature range. Undetectable and the various effects that inevitably occur at high temperatures can affect this relationship in a complex way.

Many experiments have already been conducted using exotic materials (YbRh2Si2) that exhibit strange metal behavior over a very wide temperature range, but surprisingly, from this extreme “strange metal” state. Superconductivity does not seem to appear. “Theoretical considerations have already been put forward here to justify why superconductivity is simply not possible,” said Silke Bühler-Paschen. “Still, I decided to revisit this material.”

Record temperature

The Vienna University of Technology has access to a particularly powerful cold laboratory. “There, we can study materials under more extreme conditions than other research groups have ever been able to do,” explains Silke Bühler-Paschen.First, the team was able to show that it is linear with YbRh2Si2 Relationship There is an even wider temperature range between resistance and temperature than previously thought. And they made an important discovery. At very low temperatures of only 1 millikelvin, strange metals turn into superconductors.

“This makes our material ideally suitable for seeing how strange metal behavior leads to superconductivity,” says Silke Bühler-Paschen.

Paradoxically, the fact that materials become superconducting only at very low temperatures guarantees that they can be used to study high-temperature superconductivity particularly well. Superconductivity At these very low temperatures, it looks particularly good because the other effects of this regime do not overlap. In our material, this is the localization of some of the conduction electrons at the quantum critical point.There are signs that a similar mechanism may be involved in high temperature behavior Superconductor It’s like the famous copper oxide, “says Silke Bühler-Paschen.

Review of pressure effects on iron-based high-temperature superconductors

For more information:
DH Nguyen et al, Extremely Strange Metal Superconductivity, Nature Communications (2021). DOI: 10.1038 / s41467-021-24670-z

Quote: Understanding High Temperature Superconductivity Using Ultra Low Temperature (21 July 2021) 21 July 2021 Obtained from superconductivity.html

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Understanding High Temperature Superconductivity Using Ultra Low Temperature

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