1State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China 2State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200438, China 3Frontier Science Center for Quantum Information, Beijing 100084, China 4Beijing Academy for Quantum Information Sciences, Beijing 100084, China
Abstract：We report transport measurements on Josephson junctions consisting of Bi$_{2}$Te$_{3}$ topological insulator (TI) thin films contacted by superconducting Nb electrodes. For a device with junction length $L = 134$ nm, the critical supercurrent $I_{\rm c}$ can be modulated by an electrical gate which tunes the carrier type and density of the TI film. $I_{\rm c}$ can reach a minimum when the TI is near the charge neutrality regime with the Fermi energy lying close to the Dirac point of the surface state. In the p-type regime the Josephson current can be well described by a short ballistic junction model. In the n-type regime the junction is ballistic at 0.7 K $ < T < 3.8$ K while for $T < 0.7$ K the diffusive bulk modes emerge and contribute a larger $I_{\rm c}$ than the ballistic model. We attribute the lack of diffusive bulk modes in the p-type regime to the formation of p–n junctions. Our work provides new clues for search of Majorana zero mode in TI-based superconducting devices.
Yang F, Qu F, Shen J, Ding Y, Chen J, Ji Z, Liu G, Fan J, Yang C, Fu L and Lu L 2012 Phys. Rev. B86 134504
[12]
Williams J R, Bestwick A J, Gallagher P, Hong S S, Cui Y, Bleich A S, Analytis J G, Fisher I R and Goldhaber-Gordon D 2012 Phys. Rev. Lett.109 056803
[13]
Qu F M, Yang F, Shen J, Ding Y, Chen J, Ji Z, Liu G, Fan J, Jing X, Yang C and Lu L 2012 Sci. Rep.2 339
[14]
Veldhorst M, Snelder M, Hoek M, Gang T, Guduru V K, Wang X L, Zeitler U, van der Wiel W G, Golubov A A, Hilgenkamp H and Brinkman A 2012 Nat. Mater.11 417
[15]
Cho S, Dellabetta B, Yang A, Schneeloch J, Xu Z, Valla T, Gu G, Gilbert M J and Mason N 2013 Nat. Commun.4 1689
Oostinga J B, Maier L, Schüffelgen P, Knott D, Ames C, Brüne C, Tkachov G, Buhmann H and Molenkamp L W 2013 Phys. Rev. X3 021007
[18]
Sochnikov I, Bestwick A J, Williams J R, Lippman T M, Fisher I R, Goldhaber-Gordon D, Kirtley J R and Moler K A 2013 Nano Lett.13 3086
[19]
Wiedenmann J, Bocquillon E, Deacon R S, Hartinger S, Herrmann O, Klapwijk T M, Maier L, Ames C, Brüne C, Gould C, Oiwa A, Ishibashi K, Tarucha S, Buhmann H and Molenkamp L W 2016 Nat. Commun.7 10303
Takeshige Y, Matsuo S, Deacon R S, Ueda K, Sato Y, Zhao Y F, Zhou L, Chang C Z, Ishibashi K and Tarucha S 2020 Phys. Rev. B101 115410
[22]
Schüffelgen P, Rosenbach D, Li C, Schmitt T W, Schleenvoigt M, Jalil A R, Schmitt S, Kölzer J, Wang M, Bennemann B, Parlak U, Kibkalo L, Trellenkamp S, Grap T, Meertens D, Luysberg M, Mussler G, Berenschot E, Tas N, Golubov A A, Brinkman A, Schäpers T and Grützmacher D 2019 Nat. Nanotechnol.14 825
[23]
Li Y Y, Wang G, Zhu X G, Liu M H, Ye C, Chen X, Wang Y Y, He K, Wang L L, Ma X C, Zhang H J, Dai X, Fang Z, Xie X C, Liu Y, Qi X L, Jia J F, Zhang S C and Xue Q K 2010 Adv. Mater.22 4002
[24]
Chen J, Qin H J, Yang F, Liu J, Guan T, Qu F M, Zhang G H, Shi J R, Xie X C, Yang C L, Wu K H, Li Y Q and Lu L 2010 Phys. Rev. Lett.105 176602
[25]
Yoshimi R, Tsukazaki A, Kozuka Y, Falson J, Takahashi K S, Checkelsky J G, Nagaosa N, Kawasaki M, Tokura Y 2015 Nat. Commun.6 6627
[26]
Tinkham M 1996 Introduction to Superconductivity (New York: McGraw-Hill)
[27]
Shalom M B, Zhu M J, Fal'ko V I, Mishchenko A, Kretinin A V, Novoselov K S, Woods C R, Watanabe K, Taniguchi T, Geim A K and Prance J R 2016 Nat. Phys.12 318
[28]
Calado V E, Goswami S, Nanda G, Diez M, Akhmerov A R, Watanabe K, Taniguchi T, Klapwijk T M and Vandersypen L M K 2015 Nat. Nanotechnol.10 761
2021, Vol. 38 
