Superconductivity is a phenomenon in which a circuit loses resistance and becomes extremely effective under certain conditions. There are many different ways this can happen that are deemed incompatible. For the first time, researchers have discovered a bridge between two of these methods to achieve superconductivity. This new knowledge may lead to a more general understanding of phenomena and will one day become applicable.
If you’re like most people, there are three physical states in your everyday life: solid, liquid, and gas. You may be familiar with the so-called fourth physical state plasma, like a gas so hot that all of its constituent atoms split apart, leaving a super-hot mess of subatomic particles. But do you know about the so-called fifth state of matter at the opposite end of the thermometer? It is called a Bose-Einstein condensate (BEC).
“BEC is a single state of matter because it is not made of particles but waves,” said Associate Professor Kozo Okazaki from the Institute of Solid State Physics at the University of Tokyo. “As they cool down closer not absolute, atoms of certain materials become stained out into space. This staining increases until the atoms – now more like waves rather than particles – overlap, become indistinguishable from each other. The resulting matter behaves like a single entity with new properties that previous solid, liquid or gaseous states lacked, such as superconductivity. Until recently superconducting BECs were only theoretical, but we have now demonstrated this in the lab with a new material based on iron and selenium (a non-metallic element). “
This is the first time that a BEC has been experimentally verified to act as a superconductor; however, other manifestations of matter, or mode, can also give rise to superconductivity. The Bardeen-Cooper-Shrieffer (BCS) mode is an arrangement of matter such that when cooled to near absolute zero, the constituent atoms slow down and line up, allowing electrons to pass easily. than. This effectively makes the resistance of such materials zero. Both BCS and BEC require freezing conditions and both are involved in the activity of atoms slowing down. But the modes are completely different. Researchers have long believed that a more general understanding of superconductivity can be obtained if the regimes can be found overlapping in some way.
“The BEC’s superconductivity demonstration is a means to an end; Okazaki said we were really hoping to explore the overlap between the BEC and the BCS. “It’s incredibly challenging, but our unique machine and observation methods confirm that – there’s a smooth transition between these modes. And this suggests a more general fundamental theory behind superconductivity. It’s an exciting time to work in the field. “
Okazaki and his team used laser emission spectroscopy based on extremely low temperature and high energy resolution to observe how electrons behave in the transition of materials from BCS. to BEC. Electrons behave differently in the two modes, and the change between them helps fill some of the gaps in the larger picture of superconductivity.
Superconductivity is not just about laboratory curiosity, though; Superconducting devices such as electromagnets have been used in applications, the Large Hadron Collider, the world’s largest particle accelerator, is one such example. However, as explained above, these require supercooling temperatures to prevent the development of superconducting devices that we can expect to see on a daily basis. Therefore, it is not surprising that much attention is being paid to finding a way to form superconductors at higher temperatures, maybe even room temperature a day.
“With the convincing evidence of superconducting BECs, I think it will motivate other researchers to discover superconductivity at ever higher temperatures,” Okazaki said. “Right now sounds like science fiction, but if superconductivity can happen near room temperature, our energy production capacity will greatly increase and our energy needs. will go down. ”
Reference: “Bose-Einstein condensation superconductors caused by disappearance of nematic states” by Takahiro Hashimoto, Yuichi Ota, Akihiro Tsuzuki, Tsubaki Nagashima, Akiko Fukushima, Shigeru Kasahara, Yuji Matsuda, Kohei Matsuura, Yuta Mizukami, Takasada Shibauchi, Shik Shin, and Kozo Okazaki, November 6, 2020, Scientific advance.
DOI: 10.1126 / sciadv.abb9052
This study was supported by Grants-in-Aid for Scientific Research (KAKENHI) (Grants JP19H00651, JP19H01818, JP18H05227, JP19H00649, JP18H01177, JP18K13492, JP20H02600) and on the Creative Fields “Quantum liquid crystal ”(Grant number JP19H05824 JP19H05826) and“ Topological Materials Science ”(Grant number JP15H05852) from the Japan Science Promotion Association (JSPS). TH recognizes the JSPS Research Fellowship for Young Scientists (DC2).