We’re constantly surrounded by background electromagnetic noise from cell phones, Wi-Fi routers, power lines and natural sources. Noise we often regard as an unnecessary disturbance, or even as dangerous. But recently, a research team involving the University of Freiburg discovered a material that can convert it quite efficiently into electrical signals and currents capable of operating electronic devices without batteries, light sources or mechanical drives
Imagine a device that, despite the failure of all traditional power sources, would continue to monitor and store data. This kind of autonomy could be crucial, for example, in space, disaster zones or critical infrastructures. "We didn’t expect this voltage to appear, nor for it to be so stable and reproducible", says Subhrangsu Sarkar, post-doctoral fellow at the Department of Physics and the Freiburg Center for Nanomaterials, and co-author of the study
The material is based on a multilayer thin film made of superconducting cuprates and magnetic manganites. When cooled to - 120 K (153°C), the system spontaneously generates a direct current of up to several tens of millivolts. Powerful enough to supply an external circuit, this voltage enables ambient electromagnetic fluctuations to be efficiently converted into usable electrical energy. there are no batteries, no light, no thermal gradient. And yet, our measurements show that a current is flowing," explains Subhrangsu Sarkar. It’s a striking result.
A robust passive effect
Unlike similar phenomena observed in some conventional superconductors, this effect requires no magnetic field and persists over a wide temperature range. The research team attributes it to competing electronic drives that create a complex energy landscape with an asymmetric ratchet-like shape: charge carriers excited by ambient noise flow in a given direction, generating a net electrical flux. This can be compared to the action of a mechanical ratchet, which allows movement in only one direction.
Possible applications
The team envisages applications such as self-powered sensors, memory elements and energy recovery devices that canthe team envisions applications such as self-powered sensors, memory elements and energy recovery devices that can operate under the moderate cryogenic conditions easily achieved with liquid nitrogen. Spontaneous voltage also produces reproducible switching and memory effects, making it a promising technology for multifunctional components responding to electric or magnetic fields. these results pave the way for the design of data acquisition and storage devices that are independent of an external power supply," says Christian Bernhard, Professor at the University of Freiburg. "This could prove useful for space missions, quantum computing or any other situation in which energy is limited.
A step closer to self-powered electronics
The study reveals that complex oxide heterostructures can function not only as passive components, but also as active energy converters. With further development, such systems could make a contribution to the growing number of electronic devices operating without 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). https://doi.org/10.1038/s41467-025-61014-7
Image ’Electromagnetic Waves’ by upklyak on Freepik
