🤯 Superconductivity Breakthrough: A Stunning New Twist! ⚡
Science
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Researchers investigated the interaction between hexagonal boron nitride and κ-(BEDT-TTF)2Cu[N(CN)2]Br, a mixed copper and organic superconductor. A device was constructed, layering the κ-ET with boron nitride. Observations revealed that the frequency of the stretching of a carbon-carbon double bond aligned with infrared wavelengths transmitted through the boron nitride. The team noted that the presence of boron nitride reduced the force required to bring a magnet closer to the superconductor. This suggests a potential mechanism for mediating interactions between materials, offering a new perspective on superconductivity.
THE ROLE OF VIRTUAL PHOTONS
Interactions between neighboring materials are mediated by virtual photons. Despite the headline, this isn’t really a story about superconductivity—at least not the superconductivity that people care about, the stuff that doesn’t require exotic refrigeration to work. Instead, it’s a story about how superconductivity can be used as a test of some of the weirder consequences of quantum mechanics, one that involves non-existent particles of light that still act as if they exist. Researchers have found a way to get these virtual photons to influence the behavior of a superconductor, ultimately making it worse. That may, in the end, tell us something useful about superconductivity, but it’ll probably take a little while.
QUANTUM FIELDS AND THEIR EXCITEMENTS
The story starts with quantum field theory, which is incredibly complex, but the simplified version is that even empty space is filled with fields that could govern the interactions of any quantum objects in or near that space. You can think of different particles as energetic excitements of these fields—so a photon is simply an energetic state of the quantum field. Some of these particles have real existences we can track, like a photon emitted by a laser and absorbed by a detector some distance away. But the quantum field also allows for virtual photons, which simply act to transmit the electromagnetic force between particles. We can’t really directly detect these, but we can definitely track their effects.
BORON NITRIDE: A SELECTIVE ELECTROMAGNETIC FIELD
Like the more famous graphene, boron nitride forms a series of interlinked hexagonal rings, extending out into macroscopic sheets. The bulk material is made of sheets layered onto sheets layered onto yet more sheets. This has an effect on light transiting through the material. If light simply slams into the material, it’s possible for the light to travel in the space between the boron and nitrogen atoms. But it’s not quite that simple. Because of the regular spacing of the atoms within individual sheets and the distance between those sheets, only certain wavelengths can transit smoothly. In essence, hexagonal boron nitride forms a very distinct electromagnetic field, one that’s highly selective for a limited number of wavelengths. And that means that there are a lot of virtual photons at those wavelengths present in the material, even when no photons are around.
THE κ-ET SUPERCONDUCTOR AND ITS CHALLENGES
There’s an unusual superconductor called κ-(BEDT-TTF)2Cu[N(CN)2]Br (shortened to κ-ET) that’s a mix of copper and organic materials. It’s not a great superconductor—its critical temperature is just 12 Kelvin—but it doesn’t superconduct through the same mechanism that governs more conventional copper-based superconductors. There has been reason to expect that a carbon-carbon double bond is involved in the onset of superconductivity, but that has been difficult to test experimentally.
CORRELATING VIBRATIONS AND PHOTON FREQUENCY
The researchers involved in the new work saw that the frequency of the stretching of this carbon-carbon bond matched the infrared wavelengths that could transmit through the boron nitride. That raised the possibility that sticking a lot of virtual photons nearby could influence the carbon-carbon vibrations, and thus the superconductivity.
EXPERIMENTAL VALIDATION WITH κ-ET AND BORON NITRIDE
So, they built a device that had a piece of κ-ET superconductor and layered some boron nitride on top of it. This setup was designed to test the hypothesis that virtual photons could directly influence the behavior of the κ-ET superconductor.
REDUCING MAGNETIC FIELD FORCE WITH BORON NITRIDE
One feature of superconductors is that they expel magnetic fields. The research team found that the presence of boron nitride reduced the force needed to bring a magnet closer to the superconductor. This suggests a direct interaction between the material and the magnetic field, mediated, in part, by the virtual photons.
REFERENCE
Nature, 2025. DOI:10.1038/s41586-025-10062-6
This article is AI-synthesized from public sources and may not reflect original reporting.