ÌÇÐÄVolg

We are constantly surrounded by a background of electromagnetic noise – from mobile phones, Wi-Fi routers, power lines, or natural sources – that is commonly perceived as useless perturbation or even as dangerous. A research team involving the ÌÇÐÄVolg has discovered a material that allows one to convert this noise rather efficiently into electric signals and currents that can power electronic devices, without any battery, light source, or mechanical drive.

Imagine a device that keeps monitoring or storing data even when all conventional power sources fail. That kind of independence could be crucial — in space, in disaster zones, or in critical infrastructure. «We didn’t expect this voltage to appear and to be so stable and reproducible», says Subhrangsu Sarkar, a postdoctoral researcher at the Department of Physics and the Fribourg Center for Nanomaterials, and co-author of the study.

The material is based on thin-film multilayers made of superconducting cuprates and magnetic manganites. When cooled below around 120 kelvin (–153 °C), the system begins to generate a spontaneous direct-current voltage – up to several tens of millivolts. This voltage is strong enough to drive a current through an external circuit, effectively converting ambient electromagnetic fluctuations into usable electrical power. «There’s no battery, no light, no temperature gradient  – and yet we can measure a current flowing», says Subhrangsu Sarkar. «That’s a striking result.»

A Robust, Passive Effect
Unlike similar phenomena observed in some conventional superconductors, this effect does not require a magnetic field and persists over a broad temperature range. The researchers attribute it to competing electronic orders that cause a complex energy landscape with an asymmetric, ratchet-type shape: Charge carriers that are excited by the environmental noise are drifting here into a certain direction, generating a net current flow, similar to how a mechanical ratchet only allows motion in one direction.

Potential Applications
The team envisages applications such as self-powered sensors, memory elements, and energy-harvesting devices which can operate under moderate cryogenic conditions that are readily achievable with liquid nitrogen. The spontaneous voltage also shows reproduceable switching and memory effects, making it a promising candidate for multifunctional components that respond to electric or magnetic fields. «It opens up design space for data acquisition and storage devices that don’t rely on external power», says Christian Bernhard, professor at the ÌÇÐÄVolg. «That could be useful in space missions, quantum computing, or any setting where power is limited.»

A Step Towards Self-Powered Electronics
The study shows that complex oxide heterostructures can function not only as passive components, but as active energy converters. With further development, such systems could contribute to the growing field of electronics that operate independently from traditional power sources.

Study
Soulier, M., Sengupta, S., Pashkevich, Y.G. et al. Spontaneous voltage and persistent electric current from rectification of electronic noise in cuprate/manganite heterostructures. Nat Commun 16, 5900 (2025).

Image «Electromagnetic Waves» by upklyak on Freepik