Extended Data Fig. 4: Superconductivity state characterization in device D1.
From: Untying the insulating and superconducting orders in magic-angle graphene
The right- (left-) hand panels refers to the superconductivity pocket in the valence (conductance) band on the top panel of Fig. 1c. a, b, Temperature activation of superconductivity for both pockets on the absolute resistivity scale. The insets demonstrate a zoomed-in range of temperatures from 0 K to 1.5 K. c, d, Berezinskii–Kosterlitz–Thouless (BKT) measurements of differential resistance dVxx/dI versus d.c. current bias Idc for both superconductivity pockets. The insets show d.c. voltage as a function of d.c. current bias taken at different temperatures for optimally doped superconductivity states. e, f, Differential conductance dVxx/dI (colour scales) as a function of perpendicular magnetic field B and d.c. current bias Idc shows distinct diamond-like features for both pockets. Zoomed-in images (to the right of each panel) show clear Fraunhofer interference patterns, which are a firm proof of superconductivity. g, h, Ginzburg–Landau coherence length measurements for both pockets. Critical field Bc⊥ versus critical temperature Tc taken at half the normal state resistance values. Black dots refer to experimentally obtained values; blue lines are linear fits to the data. We estimate coherence lengths ξGL = 38 nm (g) and ξGL = 101 nm (h).
