Researchers from ICMAB-CSIC, the Politecnico di Milano and Université de Liège have adapted a direct laser writing technique that allows them to “draw” superconducting properties in a material. The result is a new way to locally program the behavior of a superconductor, tuning it from a fully superconducting state to an insulating one with extraordinary precision.
High-temperature superconductors (HTSC) are materials that can conduct electricity without resistance at higher temperatures than conventional superconductors. Since they can operate at temperatures achievable using inexpensive liquid nitrogen cooling, they are considered promising candidates for future applications such as quantum technologies, superconducting electronics or next-generation memory devices.
However, patterning HTSC is particularly difficult at very small scales, as their ceramic nature makes them sensitive to conventional micro- and nanofabrication methods. The material’s oxygen level is key to determining its behavior: whether it is superconducting or insulating.
“Having a whole homogeneous sample, all well oxygenated, is easy. So is having it uniformly deoxygenated,” says Anna Palau, one of the paper’s corresponding authors. “The difficult part is to have small patterns with different oxygenation levels throughout the same film.”
The paper is published in the journal Advanced Functional Materials.
A laser that ‘draws’ like a pen
To overcome this limitation, the researchers used a focused laser to locally modify the material, controlling the oxygen levels point by point with high precision. By varying the laser power and exposure time, the researchers were able to create regions with different properties, allowing them to pattern the material much like drawing with a pen on paper. The resulting pattern can have insulating regions next to superconducting ones, as well as intermediate gradients.
“This approach opens new possibilities for the design of superconducting devices with tailored properties. The ability to locally tune superconducting behavior could be exploited in devices such as resonators, memory elements and components for quantum technologies, and could contribute to more energy-efficient information and communication technologies,” explain Edoardo Albisetti and Daniela Petti, corresponding authors of the study with Palau.
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