Figure 2: Quantum confinement of the RBS.
(a) Conductance, G, as function of top-gate voltage (VTG) at back-gate voltage (VBG) −1.6 V, showing large amplitude oscillations. The oscillations are observed when the GLs are populated by MLG-like p-type carriers, whereas the LGR contains BLG-like n-type carriers (inset to a). (b) Calculated transmission probability at a single pn interface in the giant oscillation regime. Interspecies quantum matrix elements do not have a strong parallel momentum (k||) dependence, and the Fermi surface mismatch injects carriers preferentially into the low k|| RBS, leading to the giant oscillations. (c) Conductance as function of VTG at VBG=−10 V, showing the chirality-assisted decoupling regime. The interface separates BLG-like electron and hole-doped regions (inset), and the measured conductance shows only small-amplitude fluctuations (see also Supplementary Fig. S4). (d) Calculated transmission probability at a single pn interface for the electrostatic conditions in (c). In this regime, transmission probability is dominated by BLG–BLG anti-Klein tunnelling: the pseudospin mismatch between k||=0 holes in the GL and k||=0 electrons in the LGR suppresses transmission through the RBS28, resulting in a dip in the normal transmission probability and, ultimately, the suppression of the giant oscillations.
