Extended Data Fig. 7: Zero-bias peak stability in device 2 (W1 = 80 nm). | Nature

Extended Data Fig. 7: Zero-bias peak stability in device 2 (W1 = 80 nm).

From: Evidence of topological superconductivity in planar Josephson junctions

Extended Data Fig. 7

a, G as a function of Φ threading the SQUID loop and Vsd measured at different values of B|| in device 2 at V1 = −191 mV. b, Third harmonic of the current \({I}_{3\omega }\left({V}_{{\rm{sd}}}=0\right)\) measured by the lock-in amplifier at zero bias as a function of V1 and Φ for different values of B||. \({I}_{3\omega }\left({V}_{{\rm{sd}}}=0\right)\propto -G^{\prime\prime} \left({V}_{{\rm{sd}}}=0\right)\) \(=-{\left.\left({\partial }^{2}G/\partial {V}^{2}\right)\right|}_{{V}_{{\rm{sd}}}=0}\), as shown in the Methods and Extended Data Fig. 6. A positive value of \({I}_{3\omega }\left({V}_{{\rm{sd}}}=0\right)\) corresponds to a ZBP in conductance as a function of Vsd. As B|| is increased, the ZBP expands in phase and in V1 range, consistent to what is observed in Fig. 3 of the main text for device 1. c, \({I}_{3\omega }\left({V}_{{\rm{sd}}}=0\right)\) measured by the lock-in amplifier at zero bias as a function of B|| and Φ for different values of V1. A positive value of \({I}_{3\omega }\left({V}_{{\rm{sd}}}=0\right)\) corresponds to a ZBP in conductance as a function of Vsd. The critical field at which the ZBP first appear is minimized at φ ≈ π. The behaviour of the ZBP is tuned by V1 and is qualitatively consistent with the topological phase diagrams shown in Extended Data Fig. 2a, b.

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