Asymmetric Fraunhofer Spectra in a Bi<sub>2</sub>Se<sub>3</sub> Josephson Junction
ORAL
Abstract
Josephson junctions with topological insulators as their weak link (S–TI–S junctions) are predicted to host Majorana fermions. But the details of S–TI–S current-phase relations and their interplay with magnetic fields are not completely understood. We fabricate a Bi2Se3 junction with NbTi leads and measure Fraunhofer patterns of the junction with applied in-plane fields. We observe Faunhofer patterns with aperiodic node spacings. These asymmetries appear even at zero parallel field and for temperatures up to 1 K. The anomalous features are compared to asymmetric Fraunhofer patterns expected for finite Cooper pair momentum shifts as well as geometric effects, withthe conclusion that geometric effect can dominate. These results are important for differentiating geometrical phase shifts from those caused by Cooper pair momentum shifting, Majorana mode signatures, or other unconventional superconducting behavior.
*This work was funded by the DOE 'Quantum Sensing and Quantum Materials' Energy Frontier Research Center under Grant DE-SC0021238 for support of analysis/manuscript preparation, and the NSF under DMR 17-10437 for fabrication/experimental support. The experiment was carried out in part in the Materials Research Laboratory Central Research Facilities, University of Illinois, and using some facilities of the Illinois MRSEC, supported by NSF DMR-1720633.
–
Publication:Beach, Alexander, Dalmau Reig-i-Plessis, Gregory MacDougall, and Nadya Mason. "Asymmetric Fraunhofer Spectra in a Topological Insulator-Based Josephson Junction." Journal of Physics: Condensed Matter 33, no. 42 (2021): 425601. https://doi.org/10.1088/1361-648x/ac15d7.
