Probing the minigap in topological insulator-based Josephson junctions under radio frequency irradiation*

Project supported by the National Basic Research Program of China (Grant Nos. 2016YFA0300601, 2017YFA0304700, and 2015CB921402), the National Natural Science Foundation China (Grant Nos. 11527806, 91221203, 11174357, 91421303, and 11774405), and the Strategic Priority Research Program B of the Chinese Academy of Sciences (Grant Nos. XDB07010100 and XDB28000000), and the Beijing Municipal Science & Technology Commission, China (Grant No. Z191100007219008).
Yang Guang1, 2, Lyu Zhaozheng1, 2, Zhang Xiang1, 2, Qu Fanming1, 3, 4, †, Lu Li1, 2, 3, 4, 5, ‡
       

Differential contact resistance in the junction. (a) The differential contact resistance dVb/dIb across the Pd–Bi2Te3 interface as a function of rf power Prf and bias current Ib. (b) The dVb/dIb as a function of bias current Ib in the absence of rf irradiation (red curve), together with the BTK fitting (black curve). (c) The dVb/dIb calculated from the RSJ model and the BTK theory. The black line represents a characteristic current Ie at zero rf power, beyond which the signature of superconductivity disappears. The red dashed line represents the sum of Ie and the amplitude of the rf driving alternating current Irf0′ across the Pd–Bi2Te3 interface. (d) The rf power dependence of the measured dVb/dIb–Ib curves (red, from −36 dBm to −16 dBm) and the simulated ones (black) (curves are shifted vertically for clarity).