Figure 3: Parabola-like conductance oscillations as a signature of snake states.
From: Snake trajectories in ultraclean graphene p–n junctions
(a) Charge carrier trajectory (white) along a sharp p–n junction in perpendicular magnetic field starting at the grey cross, where Rc is the cyclotron radius and n(x) is the electron density. (b) At lower p- and n-density Rc is reduced. In contrast to a, the trajectory results in current flow towards the right contact. (c) Curves of constant Rc as a function of n and B. The continuous lines are given by the condition that the cyclotron diameter 2Rc is commensurate with the sample width W. Snake states occur between the green dashed 2Rc=W and the red dashed Rc=lB line. The black dashed line indicates up to which field transport is dominated by bent Fabry–Pérot patterns (dark grey area). In the red area, scar states can occur. Below the red dashed line, Rc is smaller than the magnetic length lB and Landau levels start to dominate the transport (light grey area). (d) Conductance as a function of antisymmetric gate tuning 
and magnetic field is shown in the lower panel, and its derivative dG/dB (in arbitrary units) in the upper panel. Striking lines of high and low conductance with a parabola-like B-dependence can be observed. (e) In a smooth p–n junction (here: linear n(x)), the cyclotron orbits become elongated along the y direction due to the additional electric field caused by the density gradient. (f) 
at 120 mT. The blue dashed lines in d and f are equivalent. The inset shows lines of constant electric field Ex at the p–n interface as a function of Vright,Vleft taken from electrostatic simulations.
