Atomic-Scale Engineering of Artificial Ruddlesden-Popper Nickelate Superlattices

• Applicant: Dr. Nicolas Bonmassar
• Subject Area: Synthesis and Properties of Functional Materials ; Experimental Condensed Matter Physics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 563761404

This project explores the development of innovative materials with advanced properties by constructing artificial Ruddlesden-Popper (RP) nickelate structures. These materials are built by stacking atomic layers to mimic the crystal structure of conventional RP phases. We will create "superlattices" in which alternating layers of different nickelate compounds are stacked in precise sequences. The goal is to determine if this approach can produce defect-free, high-quality structures with the desired properties, using advanced tools such as transmission electron microscopy and X-ray diffraction for validation. This method has shown success in related materials such as manganites, but the challenge is to optimize the growth conditions for these artificial nickelates. A key focus is on chemically modifying the materials to introduce "holes," which are essentially missing electrons that can alter how electricity flows through the material. Specifically, we will explore doping the "rock salt" layers with elements such as strontium, barium, or calcium. These dopants are expected to improve the material's properties, but it remains unclear whether they integrate uniformly or cluster in specific regions. Using state-of-the-art spectroscopy and imaging techniques, the researchers will pinpoint the exact locations of these dopants and analyze their effects on the material's structure and strain. Understanding these effects is essential to establishing a link between atomic-scale modifications and the overall properties of the material. One of the most ambitious goals of the project is to achieve high temperature superconductivity - the ability of a material to conduct electricity without resistance. Previous studies have shown that similar materials can become superconducting under high mechanical pressure. This research aims to replicate these conditions using chemical pressure (through doping) and strain applied by the substrate on which the material is grown. If successful, this approach could not only reproduce the known superconducting behavior, but also lead to materials with even higher superconducting temperatures. We will use specialized instruments to measure the superconducting properties, including resistance and magnetic behavior, under various conditions. Even if superconductivity is not realized, this research will provide valuable insights into the relationship between structure and properties in RP nickelates. For example, we could study how variations in structure affect other important behaviors, such as magnetism and metallicity, which have potential applications in advanced technologies. In addition, the findings will guide future researchers in optimizing these materials for both fundamental studies and practical applications. By applying atomic-scale engineering of quantum materials, this project aims to open up new possibilities in the design of next-generation electronic and quantum devices.

• DFG Programme: Research Grants