Scientists discover elusive ‘demonic particle’ nearly 70 years after it was first predicted, and it could be the ‘holy grail’ of superconductors
Scientists have discovered a ‘demonic particle’ that could lead to superconductors that conduct electricity at room temperature – the ‘holy grail’ of physics.
A superconductor is a certain metal or alloy capable of conducting electricity without resistance, but it must be more than 100F below freezing to function.
Researchers at the University of Illinois have recently identified a massless particle, meaning it can form at any temperature, in the metal strontium ruthenate, nearly 70 years after ‘demons’ were first predicted.
Superconductors are used in operations like train levitation and high-precision magnetic resonance imaging (MRI) machines, but materials that work at room temperature would pave the way for more powerful computers.
Today’s superconductors must be more than 100 F below freezing to conduct electricity without resistance, and they stay cool with liquid nitrogen.
Superconductivity was discovered over 100 years ago in mercury cooled to the temperature of liquid helium at -452F.
After the discovery of superconductivity in mercury, the phenomenon was also observed in other materials at very low temperatures.
Materials included various metals and a niobium-titanium alloy that could be easily made into wire.
The demon particle was first predicted by theoretical physicist David Pines in 1956, who believed that electrons would react “strangely” when traveling through a solid.
Electrons can lose their individuality in solids as electrical interactions cause electrons to combine to form collective units.
With enough energy, the electrons can form composite particles called plasmons with a new charge and mass determined by underlying electrical interactions.
However, the mass is usually so great that plasmons cannot form at the energies available at room temperature, but Pines theorized that there was an exception to this.
The physicist argued that if a solid has electrons in more than one energy band, like many metals, their respective plasmons can combine in an out-of-phase pattern to form a new massless and neutral plasmon: a demon.
Since demons are massless, they can form with any energy and can exist at all temperatures.
However, the elusive demon particle accidentally discovered in a specific metal is massless, meaning it can form at any temperature. In the photo, a model of the demonic particle.
This has led to speculation that they have essential effects on the behavior of multiband metals.
The discovery was made by a team of researchers led by Peter Abbamonte, a professor of physics at the University of Illinois Urbana-Champaign, who identified Pines’ prediction while studying the metal strontium ruthenate.
The experiment was not related to superconductors, but the metal is similar to high-temperature superconductors without being.
The researchers were conducting the first study of the electronic properties of metal by bombarding it with electrons, which summoned the demon within the metal’s characteristics.
Abbamonte was working with a former graduate student Ali Husain on the project, who said: ‘At first, we had no idea what it was about.
Demons are not in the mainstream. The possibility came up early on, and we basically just laughed it off.
“But, when we started to rule things out, we started to suspect that we really had found the demon.”
Finally, Edwin Huang, a UIUC Moore Postdoctoral Fellow and a condensed matter theorist, was asked to calculate the characteristics of the electronic structure of strontium ruthenate.
The prediction of ‘Pines’ daemons requires quite specific conditions, and it was not clear to anyone whether strontium ruthenate should have a daemon,” Huang said.
“We had to perform a microscopic calculation to clarify what was going on. When we did this, we found a particle consisting of two bands of electrons oscillating out of phase with nearly equal magnitude, just as Pines described.’