Nano-fabricated superconducting quantum interference devices (nano-SQUID) are very sensitive magnetic probes that are suitable for magnetic imaging of quantum materials on the mesoscopic scale. We have developed scanning SQUID microscopes working under different environments to study local magnetic response of superconductors. In this talk, I will report our results on cuprate and Fe-based superconductors. We use both magnetometry and susceptometry to image superconducting vortices, magnetization, superfluid density and edge current in the prototypical material systems Bi 2 Sr 2 CaCu 2 O8+δ (Bi2212) and Fe(Se,Te) under different dimensionality. If time allows, I will also discuss our recent results on a potentially spin-triplet superconductor UTe 2 .  
 
References
 
1  Pan, Y. P. et al. 3D nano-bridge-based SQUID susceptometers for scanning magnetic imaging of quantum materials. Nanotechnology 30, 305303 (2019). https://doi.org:10.1088/1361-6528/ab1792
2  Xiang, B. K. et al. Flux focusing with a superconducting nano-needle for scanning SQUID susceptometry. Microsystems and Nanoengineering 9, 78 (2023).  
3  Zhu, J. et al. Direct observation of chiral edge current at zero magnetic field in odd-layer MnBi 2 Te 4 . arXiv 2307.10150 (2023).  
4  Wang, S. Y. et al. Oscillating paramagnetic Meissner effect and Berezinskii-Kosterlitz- Thouless transition in Bi 2 Sr 2 CaCu 2 O8+δ monolayer. National Science Review (2023). https://doi.org:doi.org/10.1093/nsr/nwad249
5  Lin, Y. S. et al. Direct Observation of Quantum Anomalous Vortex in Fe(Se,Te). Physical Review X 13, 011046 (2023). https://doi.org:10.1103/PhysRevX.13.011046
6  Xiang, B. K. et al. Observation of long-range ferromagnetism via anomalous supercurrents in a spin-orbit coupled superconductor. arXiv 2307.10722 (2023).  
 
Coffee and pastries will be served in the hall at 11:00