Nanoscale Spatial Tuning of Superconductivity in Cuprate Thin Films via Direct Laser Writing
Cuprate high-temperature superconductors, such as Yttrium Barium Copper Oxide (YBCO), are extremely promising for emerging technologies such as low-power computing, data storage, quantum sensors and superconducting electronics. However, the realization of high-performance functional nanostructures presents formidable challenges due to the difficulty of applying conventional nanofabrication methods to such sensitive materials, making the search for alternative methods a key enabling factor. Since YBCO's superconducting and normal-state properties are highly dependent on oxygen stoichiometry, precise nanoscale control of the oxygen content represents a highly appealing approach for creating advanced nanoengineered devices. In this work, we demonstrate the precise fabrication of sub-micrometer, grayscale patterns over large areas in epitaxial YBCO thin films, achieving finely tuned optical and superconducting transport properties by locally controlling the stoichiometry through maskless direct laser writing under ambient conditions. Cryogenic magneto-optical imaging and transport measurements in irradiated devices directly demonstrate the spatial tuning of the critical temperature and carrier density with the patterning conditions. Correlated Raman microscopy and reflectometry indicate a laser-power dependent oxygen depletion in the irradiated regions. The proposed laser-controlled stoichiometry approach provides a direct and scalable method to navigate the phase diagram of high-TC superconducting oxides, offering new possibilities for integrating functional nanostructures into superconducting devices.