Quantum imaging of an Fe-Chalcogenide topological superconductor*

The family of Fe-chalcogenide superconductors FeTe_xSe_1-x possess intrinsic topological band structure, high-temperature superconductivity, and unconventional pairing symmetry, promising to develop novel, quantum-based computing strategies with improved information processing speeds and energy efficiency. To date, the magnetic properties of FeTe_xSe_1-x have remained largely unexplored, which prevents a comprehensive understanding of their underlying material properties. Exploiting nitrogen-vacancy (NV) centers in diamond, we have performed nanoscale quantum sensing and imaging of magnetic flux generated by exfoliated FeTe_0.7Se_0.3 flakes, demonstrating the strong correlation between superconductivity and emergence of ferromagnetism in FeTe_0.7Se_0.3. The coexistence of superconductivity and ferromagnetism in an established topological superconductor provides new opportunities for exploring exotic spin and charge transport behaviors in quantum materials.