Topological Insulator nano-SQUID: Flux-tunable platform for topological superconductivity
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arXiv
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| Autori principali: | , , , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2024
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| author | Nikodem, Ella Schluck, Jakob Legg, Henry F. Geier, Max Papaj, Michal Bagchi, Mahasweta Fu, Liang Ando, Yoichi |
| author_facet | Nikodem, Ella Schluck, Jakob Legg, Henry F. Geier, Max Papaj, Michal Bagchi, Mahasweta Fu, Liang Ando, Yoichi |
| contents | Many efforts have been made in the past decade to realize topological superconductivity using superconducting proximity effect, but an ideal platform is still lacking. A 3D topological insulator (TI) is promising for this purpose due to the spin-momentum-locked surface state. Here we propose a novel yet simple TI platform which gives rise to a topological phase that is robust against disorder. It consists of a bulk-insulating rectangular TI nanowire laterally sandwiched by two superconductors. In this structure, the top and bottom surfaces individually work as SNS line junctions, forming a nanometer-scale columnar SQUID in which the nanowire cross-section defines the threading magnetic flux $Φ$ in axial magnetic fields. We theoretically show that, when the two junctions are asymmetric, a robust topological phase occurs periodically for a wide range of $Φ$, independently of the chemical potential. Our experiment found that a TI device of this structure indeed behaves as a columnar nano-SQUID where the supercurrent flows only through the top and bottom surfaces with vanishing bulk contribution. Furthermore, the top/bottom asymmetry can be tuned by a back gate, a key ingredient for the topological phase. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2412_07993 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Topological Insulator nano-SQUID: Flux-tunable platform for topological superconductivity Nikodem, Ella Schluck, Jakob Legg, Henry F. Geier, Max Papaj, Michal Bagchi, Mahasweta Fu, Liang Ando, Yoichi Mesoscale and Nanoscale Physics Materials Science Strongly Correlated Electrons Superconductivity Many efforts have been made in the past decade to realize topological superconductivity using superconducting proximity effect, but an ideal platform is still lacking. A 3D topological insulator (TI) is promising for this purpose due to the spin-momentum-locked surface state. Here we propose a novel yet simple TI platform which gives rise to a topological phase that is robust against disorder. It consists of a bulk-insulating rectangular TI nanowire laterally sandwiched by two superconductors. In this structure, the top and bottom surfaces individually work as SNS line junctions, forming a nanometer-scale columnar SQUID in which the nanowire cross-section defines the threading magnetic flux $Φ$ in axial magnetic fields. We theoretically show that, when the two junctions are asymmetric, a robust topological phase occurs periodically for a wide range of $Φ$, independently of the chemical potential. Our experiment found that a TI device of this structure indeed behaves as a columnar nano-SQUID where the supercurrent flows only through the top and bottom surfaces with vanishing bulk contribution. Furthermore, the top/bottom asymmetry can be tuned by a back gate, a key ingredient for the topological phase. |
| title | Topological Insulator nano-SQUID: Flux-tunable platform for topological superconductivity |
| topic | Mesoscale and Nanoscale Physics Materials Science Strongly Correlated Electrons Superconductivity |
| url | https://arxiv.org/abs/2412.07993 |