Giant Noise in a Superconductor-Magnet Sandwich ⚡ экспресс
By measuring shot noise (a consequence of charge quantization) in superconductor/insulator/ferromagnet structures (V/MgO/Fe), the authors captured its giant surge—orders of magnitude above the calculated value. The culprit? An exotic proximity effect: the superconductor nudges neighboring layers, and thanks to spin-orbit coupling (the interplay between spin and motion), triplet superconductivity blossoms there, radically different from the original. It’s like a single word flipping the meaning of an entire phrase. Such amplified noise was previously spotted only in junctions with two superconductors, never in a solo one—this discovery forces us to rethink the role of spin-orbit effects.
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.
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.
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.