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Giant Noise in a Superconductor-Magnet Sandwich ⚡ экспресс

Original: "Giant shot noise in superconductor/ferromagnet junctions with orbital-symmetry-controlled spin-orbit coupling"
arXiv:2509.15983 · 2025-09-19 · CC BY · ⏱ 1 min · Superconductivity Quantum Physics
Electrical noise in a sandwich of superconductor, insulator, and magnet turned out to be hundreds of times larger than expected, pointing to the birth of a new kind of superconductivity.
Abstract

Scientists found that in thin stacks of a superconductor and a magnet, electrical noise skyrockets hundreds of times beyond predictions. It’s as if a quiet whisper morphs into a thunderous shout under the invisible sway of neighbors. Turns out, this influence breeds a strange, new kind of superconductivity. Could this effect rewrite what we know about materials?

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Ordinary electrical noise is like a faint hiss in headphones. This is shot noise from electrons passing through a contact. But in the experiment with a sandwich of superconducting vanadium, MgO insulator, and magnetic iron, this noise roared, becoming hundreds of times louder.

Here, noise is not a nuisance but a detector of hidden superconductivity.

The secret lies in the proximity effect: a superconductor "infects" neighboring layers with its ability to conduct current without resistance. Conventional superconductivity was explained by John Bardeen, and Leo Esaki studied tunneling effects. Usually, electrons in a superconductor form pairs with opposite spins—like two dancers spinning in opposite directions. But in this sandwich, the spins aligned in the same direction, as if both are spinning to the right. This is triplet superconductivity. It allowed current to flow unimpeded through the magnetic iron, generating giant noise.

Previously, such anomalous noise was seen only in contacts with two superconductors; here, one was enough—and this breaks the standard model. The increase in entropy due to triplet states gives this loud signal.

This discovery changes the physics of layered structures and paves the way for spintronics—electronics that uses electron spin instead of charge.

🎯 Iron, normally a magnet, in this structure temporarily turns into a superconductor—current flows without resistance through it.

S_I = 2eI
S_I is the power spectral density of shot noise, e is the electron charge, I is the average current
Scientists
Christian DopplerD. B. McLaughlinDidier QuelozMichel MayorR. A. RossiterEmmy Noether
Tags
spectroscopy Standard Model entropy
Laws
second law of thermodynamicsDoppler effectNoether's theoremBekenstein-Hawking entropyMaxwell's equationsPlanck's law
Original: arXiv:2509.15983 · CC BY · bridge42worlds