Light-Driven Breakthrough in Atom-Thin Metals Paves the Way for Next-Gen Devices
In a leap forward for the electronics industry, researchers at the University of Minnesota Twin Cities have unveiled a method to steer the flow of electricity in atom-thin metallic films at room temperature using light. This remarkable achievement could reshape the landscape of optoelectronics, memory systems, and quantum technologies, enabling faster, more energy-efficient devices.
Published in the peer-reviewed journal Science Advances, the study demonstrates that ultra-thin layers of ruthenium dioxide (RuO2), grown on titanium dioxide (TiO2), can be engineered to behave differently depending on the direction of electrical flow and their interaction with light.
Precision Engineering for Light-Metal Interaction
Bharat Jalan, senior author of the study and Shell Chair Professor in the Department of Chemical Engineering and Materials Science, explained the innovation: “We solved this problem by carefully designing ultra-thin metal layers that interact with light in new ways—something you don’t see in the thicker version of this material. This work demonstrates that we can now tailor ultrafast conductivity in metals using the same kind of precise control of epitaxial strain, a method previously reserved for semiconductors or insulators.”
By altering the way atoms stretch in different directions, the team discovered they could control the material’s light response—a phenomenon that functions at room temperature, making it ripe for real-world applications.
Challenging Long-Held Assumptions
Lead author Seunggyo Jeong, a postdoctoral researcher in the Department of Chemical Engineering and Materials Science, emphasised the significance: “This is the first time anyone has demonstrated tunable, directional ultrafast carrier relaxation in a metal at room temperature. It challenges long-held assumptions in condensed matter physics and opens a fundamentally new pathway to manipulate charge and light in metallic systems.”
This control over ultrafast carrier relaxation has far-reaching implications for optoelectronic and memory devices, which depend on the speed and efficiency with which charge carriers respond to light.
Unlocking the Potential of Structural Distortions
Co-author Tony Low, Paul Palmberg Professor in the Department of Electrical and Computer Engineering, highlighted the broader impact: “The findings provide deep insight into how subtle structural distortions—like strain relaxation—can reshape the electronic landscape of metals. This could be critical for future ultrafast and polarisation-sensitive optoelectronic technologies.”
Traditionally, metals were considered unsuitable for such precise directional control due to their complex, multi-band structures. However, the research team exploited a property called band nesting—a feature of electronic structure—allowing the ultrafast response to vary depending on measurement direction.
From Theory to Real-World Application
The implications for the technology sector are substantial. Devices that could benefit include:
- High-performance computing systems with reduced power consumption
- Next-generation data storage solutions with faster read/write speeds
- Advanced optical sensors capable of ultra-precise detection
- Secure communication devices using quantum-level control of charge flow
By integrating these engineered RuO2 films into devices, engineers could unlock significant improvements in speed, energy efficiency, and functionality.
The Road Ahead
The University of Minnesota team plans to test these ultrathin RuO2 films in working devices and investigate similar phenomena in other oxide systems. Their goal is to expand the range of materials that exhibit this directional light-charge control at practical operating conditions.
The research team also included graduate student Sreejith Nair from the Department of Chemical Engineering and Materials Science, and post-doctoral associate Seunjun Lee from the Department of Electrical and Computer Engineering. Collaborators from the Gwangju Institute of Science and Technology, Sungkyunkwan University, and the University of Kentucky also played key roles.
Funding came from the U.S. Department of Energy, the Air Force Office of Scientific Research (AFOSR), and the University of Minnesota Materials Research Science and Engineering Center (MRSEC). Experiments were supported by the University of Minnesota Characterization Facility.
Why This Matters for the Future of Electronics
The ability to steer electrical currents in metals with light, especially in films just a few atoms thick, is more than a laboratory curiosity. It could underpin a new generation of devices that operate at unprecedented speeds and with unmatched efficiency. As the global push for faster, smaller, and greener technology accelerates, breakthroughs like this could be the difference between incremental improvements and transformative change.
If successful, this approach could ripple across industries, from supercomputing and telecommunications to medical imaging and autonomous systems, shaping the way electronic devices are designed and manufactured for decades to come.
