Emergent multicomponent phases and odd parity in unconventional superconductors

• Applicants: Professor Dr. Ilya Eremin; Professor Dr. Jörg Schmalian
• Subject Area: Theoretical Condensed Matter Physics ; Experimental Condensed Matter Physics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 449367852

The overall goal of our joint theoretical and experimental proposal is to better understand the formation of emergent multicomponent phases in unconventional superconductors in the presence of multiple orbitals, strong spin-orbit coupling with potentially non-trivial topology of the band structure, and the delicate interplay of electron-electron and pairing correlations. The examples range from moderately correlated systems such as Cu, Nb, or Sr intercalated Bi2Se3 with odd parity nematic superconductivity to strongly-correlated systems such as iron-based superconductors and Sr2RuO4. One of the main objectives of this proposal is to explore theoretically and experimentally the thermodynamic and spectroscopic features of the pairing fluctuations of these states and their competition with magnetic, orbital, and nematic instabilities and to reveal their microscopic origin and feedback on superconductivity. We plan to study the formation of the odd-parity nematic superconductivity in Bi2Se3 and related (proximity-induced) systems where electronic correlations are moderate exploring the role of van der Waals forces in the formation of the Cooper-pairing. On the other hand we plan to investigate the Fe-based chalcogenide superconductors and Sr2RuO4, where strong electronic correlations occur together with strong spin-orbit coupling. Clearly strong electronic correlations make their theoretical and experimental investigation technically more challenging. Here, we plan to further develop the phase sensitive technique to determine the phase structure of the superconducting gap in multiorbital case and study the potential role of non-trivial band topology. The specific objective of the endeavor is to develop a genuine microscopic description of the available novel experiments that describes thermodynamic and spectroscopic (STM) features of these systems on a quantitative level.

• DFG Programme: Research Grants
• International Connection: China
• Partner Organisation: National Natural Science Foundation of China
• Cooperation Partners: Professor Dr. Yaomin Dai; Professor Dr. Hai-Hu Wen; Professor Dr. Huan Yang; Professor Dr. Xiyu Zhu