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Direct observation of quantum anomalous vortex in Fe(Se,Te)
- Source :
- PhysRevX.13.011046 (2023)
- Publication Year :
- 2022
-
Abstract
- Vortices are topological defects of type-II superconductors in an external magnetic field. In a similar fashion to a quantum anomalous Hall insulator, quantum anomalous vortex (QAV) spontaneously nucleates due to orbital-and-spin exchange interaction between vortex core states and magnetic impurity moment, breaking time-reversal symmetry (TRS) of the vortex without an external field. Here, we used scanning superconducting quantum interference device microscopy (sSQUID) to search for its signatures in iron-chalcogenide superconductor Fe(Se,Te). Under zero magnetic field, we found a stochastic distribution of isolated anomalous vortices and antivortices with flux quanta $\Phi_0$. By applying a small local magnetic field under the coil of the nano-SQUID device, we observed hysteretic flipping of the vortices reminiscent of the switching of ferromagnetic domains, suggesting locally broken-TRS. We further showed vectorial rotation of a flux line linking a paired vortex-antivortex with the local field. These unique properties of the anomalous vortices satisfied the defining criteria of QAV. Our observation suggests a quantum vortex phase with spontaneous broken-TRS in a high-temperature superconductor.
Details
- Database :
- arXiv
- Journal :
- PhysRevX.13.011046 (2023)
- Publication Type :
- Report
- Accession number :
- edsarx.2208.00642
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1103/PhysRevX.13.011046