Giant shot noise in superconductor/ferromagnet junctions with orbital-symmetry- controlled spin-orbit coupling

C. González-Ruano, Ch. Shen, P. Tuero, C. Tiusan, Y. Lu, J.E. Han, I. Žutić, F. Aliev Kazanski

Nature Communications Vol. 16, pp. 9524

Summary:

By measuring the shot noise, a consequence of charge quantization, in super-conductor/insulator/ferromagnet (V/MgO/Fe) junctions, we discover a giant increase, orders of magnitude larger than expected. The origin of this giant noise is a peculiar realization of a superconducting proximity effect, where a simple superconductor influences its neighbors. Our measurements reveal largely unexplored implications of orbital-symmetry-controlled proximity effects. The importance of orbital symmetries and the accompanying spin-orbit coupling is manifested by an unexpected emergence of another superconducting region, strikingly different from the parent superconductor. Unlike vanadium’s common spin-singlet superconductivity, the broken inversion symmetry in V/MgO/Fe junctions and the resulting interfacial spin-orbit coupling lead to the formation of spin-triplet superconductivity across the ferromagnetic iron. Here, we show that the enhanced shot noise, known from Josephson junctions with two superconductors, is measured even in a single superconductor. This discovery motivates revisiting how the spin-orbit coupling and superconducting proximity effects can transform many materials.

Spanish layman's summary:

El estudio detecta un ruido eléctrico anormalmente grande en uniones superconductor/ferromagneto, señal de un efecto cuántico inesperado. La interacción en la interfaz genera un tipo poco común de superconductividad que se extiende al ferromagneto, revelando nuevas formas de controlar materiales mediante acoplamiento espín-órbita.

English layman's summary:

This study detects an unusually large electrical noise in superconductor/ferromagnet junctions, a sign of an unexpected quantum effect. The interaction at the interface induces a rare type of superconductivity that extends to the ferromagnet, revealing new ways to control materials via spin-orbit coupling.

JCR-JIF Impact Factor and WoS quartile: 18,100 - Q1 (2025)

DOI reference: https://doi.org/10.1038/s41467-025-64493-w

Published on paper: December 2025.

Published on-line: October 2025.

Citation:
C. González-Ruano, Ch. Shen, P. Tuero, C. Tiusan, Y. Lu, J.E. Han, I. Žutić, F. Aliev Kazanski, "Giant shot noise in superconductor/ferromagnet junctions with orbital-symmetry- controlled spin-orbit coupling", Nature Communications, Vol. 16, pp. 9524, December 2025. [Online: October 2025] doi: 10.1038/s41467-025-64493-w