Fig. 2: Veselago interference and localization.
From: Gate-tunable Veselago interference in a bipolar graphene microcavity
a–c Measured 4-probe resistance of cavity as a function of n1 and n2 in three devices. Resistance peaks are visible at |n1| = |n2| (red), |n1| = 4|n2| (green), 4|n1| = |n2| (blue) and 9|n1| = |n2| (purple), d When |n1| = |n2|, a symmetric pn-junction is defined in the cavity. Carriers injected into the cavity (with a low probability p and a small incident angle) undergo Veselago refraction, followed by reflection at the oppositive cavity boundary, then a second Veselago refraction to the original position. At B = 0, the process localizes carriers and gives rise to measured resistance peaks. e, f Similarly, a closed interference loop (bold) can be formed via a sequence of two refractions and three reflections at |n1| = 4|n2| and 4|n1| = |n2|, leading to a second-order Veselago interference peak.
