{"id":3489,"date":"2023-07-10T16:28:39","date_gmt":"2023-07-10T16:28:39","guid":{"rendered":"http:\/\/web.nano.cnr.it\/heun\/?page_id=3489"},"modified":"2025-06-19T15:57:01","modified_gmt":"2025-06-19T15:57:01","slug":"sgm-21","status":"publish","type":"page","link":"https:\/\/web.nano.cnr.it\/heun\/research\/sgm-21\/","title":{"rendered":"SGM 21"},"content":{"rendered":"

Half-integer Shapiro steps in InSb\/Nb Josephson junctions<\/h2>\n

InSb is a high-quality narrow band gap semiconductor with strong spin-orbit coupling, which makes it the ideal platform to develop architectures able to coherently control new states of matter with topological properties. We present transport data on hybrid Josephson junctions made from InSb nanoflags with Nb contacts. These InSb nanoflags have a typical size of L ~ 2.8 \u03bcm, W ~ 500 nm, and d ~ 100 nm. A mobility of 29.500 cm2<\/sup>\/(Vs) at an electron density of 8.5 \u00d7 1011<\/sup> cm-2<\/sup> is measured, which results in an electron mean free path \u2113\ud835\udc52<\/sub> ~ 500 nm. At variance to previous work, in the junctions presented here the Nb is directly deposited on the S-passivated InSb nanoflags.<\/p>\n

The junction discussed in the following has a length L of 80 nm and a width W of 700 nm. Since \u2113\ud835\udc52<\/sub> > \ud835\udc3f, the transport in the junction is ballistic. The Nb has a critical temperature of ~ 8.9 K. This corresponds to a BCS gap of ~ 1.3 meV, so that the induced superconducting coherence length exceeds L, which places the device in the short-junction limit. At 30 mK, the junction shows a critical current above 100 nA. The temperature dependence of the critical current above 500 mK is well described by a short-junction model with interface transparency 0.93. However, a detailed analysis of the full temperature range suggests that the current in the junction is the sum of the short channel contribution and a long channel contribution, for which a path length of about 3.5 \u03bcm is obtained (Fig. 1a). This result is consistent with the quantitative analysis of the anomalous Fraunhofer pattern measured on the same junction (Fig. 1b). Finally, irradiating the junction with microwaves, half-integer Shapiro steps are observed (Fig. 1c), which are robust in temperature and persist up to 1 K, suggesting their possible nonequilibrium origin.<\/p>\n

\"\"<\/a>Figure 1: <\/b>(a) Temperature dependence of the critical current. (b) Anomalous Fraunhofer pattern. (c) Half-integer Shapiro steps.<\/i><\/p>\n

Publications:<\/p>\n

    \n
  1. Andrea Iorio: Superconducting circuits with metallic and semiconducting weak-links<\/i>, PhD Thesis<\/a>, Scuola Normale Superiore<\/a>, Pisa, Italy, 2023.\n
  2. Andrea Iorio, Alessandro Crippa, Bianca Turini, Sedighe Salimian, Matteo Carrega, Luca Chirolli, Valentina Zannier, Lucia Sorba, Elia Strambini, Francesco Giazotto, Stefan Heun: Half-integer Shapiro steps in highly transmissive InSb nanoflag Josephson junctions<\/i>, arXiv:2303.05951 [cond-mat.supr-con]<\/a>.\n
  3. A. Iorio, A. Crippa, B. Turini, S. Salimian, M. Carrega, L. Chirolli, V. Zannier, L. Sorba, E. Strambini, F. Giazotto, and S. Heun: Half-integer Shapiro steps in highly transmissive InSb nanoflag Josephson junctions<\/i>, Phys. Rev. Res. 5 (2023) 033015<\/a>.<\/li>\n
  4. Highly transmissive InSb nanoflag Josephson junctions, CNR Nano Activity Report 2024<\/a>. [Pages 62-63<\/a>]<\/li>\n<\/ol>\n

    Presented at:<\/p>\n

      \n
    1. Stefan Heun: Non-equilibrium microwave induced supercurrents in highly transmissive InSb nanoflag Josephson junctions<\/i>, AndQC Meeting, Basel, Switzerland, 2-3 March 2023. [Talk<\/a>]<\/li>\n
    2. A. Iorio, A. Crippa<\/u>, B. Turini, S. Salimian, M. Carrega, L. Chirolli, V. Zannier, L. Sorba, E. Strambini, F. Giazotto, and S. Heun: Half-integer Shapiro steps in highly transmissive InSb nanoflag Josephson junctions<\/i>, Hybrid Quantum Technologies Workshop 2023<\/a>, Klosterneuburg\/Vienna (Austria), 3\u20136 April 2023. [Abstract<\/a>] [Poster<\/a>]<\/li>\n
    3. A. Iorio, B. Turini, S. Salimian, M. Carrega, L. Chirolli, A. Crippa, E. Strambini, V. Zannier, L. Sorba, F. Giazotto, and S. Heun<\/u>: Half-integer Shapiro steps in InSb \/Nb Josephson junctions<\/i>, Bound States 2023<\/a>, Budapest (Hungary), 11-14 June 2023. [Abstract<\/a>] [Talk<\/a>]<\/li>\n
    4. Valentina Zannier, Isha Verma, Sedighe Salimian, Stefan Heun, Francesca Rossi, Daniele Ercolani, Fabio Beltram, and Lucia Sorba<\/u>: Free-standing InSb nanostructures: growth, morphology control and electrical characterization<\/i>, International Conference on Crystal Growth and Epitaxy<\/a>, Naples, Italy, 30 July – 4 August 2023. [Talk<\/a>]<\/li>\n
    5. A. Iorio: Superconducting circuits with metallic and semiconducting weak-links<\/i>, PhD thesis defense, Scuola Normale Superiore<\/a>, Pisa, Italy, 22 September 2023. [Talk<\/a>]<\/li>\n
    6. S. Heun: Highly transmissive InSb nanoflag Josephson junctions<\/i>, ISSP<\/a>, The University of Tokyo<\/a>, Japan (Prof. Y. Hasegawa), 5 October 2023. [Abstract<\/a>] [Talk<\/a>]<\/li>\n
    7. A. Iorio, B. Turini, S. Salimian, A. Crippa, E. Strambini, V. Zannier, M. Carrega, L. Chirolli, F. Beltram, L. Sorba, F. Giazotto, and S. Heun<\/u>: Highly transmissive InSb nanoflag Josephson junctions<\/i>, NQSTI Workshop<\/a>, Rome, Italy, 15 \u2013 16 January 2024 (oral). [Abstract<\/a>] [Talk<\/a>]<\/li>\n
    8. A. Iorio, A. Crippa, B. Turini, S. Salimian, M. Carrega, L. Chirolli, V. Zannier, L. Sorba, E. Strambini, F. Giazotto, and S. Heun<\/u>: Half-integer Shapiro steps in highly transmissive InSb nanoflag Josephson junctions<\/i>, DPG Spring Meeting<\/a>, Berlin, Germany, 17 \u2013 22 March 2024 (oral). [Abstract<\/a>] [Talk<\/a>]<\/li>\n
    9. S. Heun: Hybrid superconductor \u2013 semiconductor Josephson junctions for quantum technologies<\/i>, Workshop Il CNR nel panorama regionale delle Scienze e Technologie Quantistiche<\/a>, Naples, Italy, 7 June 2024 (invited). [Abstract<\/a>] [Talk<\/a>]<\/li>\n
    10. S. Heun: Josephson junctions based on high mobility InSb nanoflags for advanced quantum technologies<\/i>, Workshop on Non-equilibrium quantum many-body systems<\/a>, Genoa, Italy, 10 \u2013 12 July 2024. [Abstract<\/a>] [Talk<\/a>]<\/li>\n
    11. A. Iorio, A. Crippa, B. Turini, S. Salimian, M. Carrega, L. Chirolli, V. Zannier, L. Sorba, E. Strambini, F. Giazotto, and S. Heun<\/u>: Half-integer Shapiro steps in highly transmissive InSb nanoflag Josephson junctions<\/i>, 36th International Conference on the Physics of Semiconductors (ICPS)<\/a>, Ottawa, Canada, 28 July \u2013 2 August 2024 (oral). [Abstract<\/a>] [Talk<\/a>]<\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"

      Half-integer Shapiro steps in InSb\/Nb Josephson junctions InSb is a high-quality narrow band gap semiconductor with strong spin-orbit coupling, which makes it the ideal platform to develop architectures able to coherently control new states of matter with topological properties. We present transport data on hybrid Josephson junctions made from InSb nanoflags with Nb contacts. These […]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":870,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-3489","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/web.nano.cnr.it\/heun\/wp-json\/wp\/v2\/pages\/3489","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/web.nano.cnr.it\/heun\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/web.nano.cnr.it\/heun\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/web.nano.cnr.it\/heun\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/web.nano.cnr.it\/heun\/wp-json\/wp\/v2\/comments?post=3489"}],"version-history":[{"count":45,"href":"https:\/\/web.nano.cnr.it\/heun\/wp-json\/wp\/v2\/pages\/3489\/revisions"}],"predecessor-version":[{"id":3969,"href":"https:\/\/web.nano.cnr.it\/heun\/wp-json\/wp\/v2\/pages\/3489\/revisions\/3969"}],"up":[{"embeddable":true,"href":"https:\/\/web.nano.cnr.it\/heun\/wp-json\/wp\/v2\/pages\/870"}],"wp:attachment":[{"href":"https:\/\/web.nano.cnr.it\/heun\/wp-json\/wp\/v2\/media?parent=3489"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}