Massless ‘Demon Particle’ Could Be the ‘Holy Grail’ of Superconductors

A massless particle was discovered, and it could revolutionize our knowledge about superconductors. "Demon particle" could reportedly be the "holy grail" of physics.

Demon Particle the Holy Grail of Superconductors

Nearly 70 years after the initial predictions of "demons," scientists at the University of Illinois have discovered a massless particle in the metal strontium ruthenate that may form at any temperature.

However, materials that work at average temperatures might pave the path for more potent computers. Superconductors are employed in operations like floating trains and extremely accurate magnetic resonance imaging (MRI) scanners.

David Pines, a theoretical physicist, postulated the demon particle in 1956 because he thought electrons would behave "strangely" as they passed through solids. In solids, where electric interactions cause the electrons to unite to form collective units, electrons may lose their individuality.

When enough energy is available, the electrons can combine to produce composite particles known as plasmons with new charges and masses defined by the underlying electric interactions.

However, because the mass is often so big, plasmons cannot form with the energy present at ambient temperature. Pines postulated that there might be an exception to this rule.

According to the physicist, if a solid contains electrons in more than one energy band, as many metals do, then their plasmons may combine in an out-of-phase pattern to create a new plasmon that is massless and neutral - a devil.

Demons have no mass, which allows them to develop from any energy and exist at any temperature.

A group of scientists led by the University of Illinois at Urbana-Champaign physics professor Peter Abbamonte achieved the discovery after spotting Pines' forecast while researching the metal strontium ruthenate. The metal is akin to high-temperature superconductors without actually being one, although the experiment had nothing to do with them.

By bombarding the metal with electrons, which brought the demon within its characteristics to life, researchers undertook the metal's first survey of its electronic properties.

Abbamonte admitted they initially had no idea what it was. They laughed when the possibility that those demons were raised but later realized that they may have discovered the demon particles.

Condensed matter theorist Edwin Huang, a Moore Postdoctoral Scholar at UIUC, was eventually tasked with calculating the characteristics of strontium ruthenate's electronic structure.

Huang said Pines' prophecy of demons requires quite particular circumstances, and it was unclear to everyone if strontium ruthenate should have a demon. To understand what was happening, they had to conduct a microscopic computation. When they performed it, they discovered a particle made up of two-electron bands oscillating in an almost equal-amplitude out-of-phase manner, just as Pines predicted.

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What Is a Superconductor?

A superconductor is a substance that reaches superconductivity, a state of matter in which magnetic forces cannot penetrate without electrical resistance. In a superconductor, an electric current can last forever.

Typically, superconductivity can only be reached at extremely low temperatures. From MRI equipment to ultra-fast maglev trains that employ magnets to elevate the trains off the track to decrease friction, superconductors are used in a wide range of everyday applications.