Fig. 2: Ballistic transport of BZ fermions over micrometer distances.

a Schematic of bend resistance measurements. Current I is applied between contacts 3 and 4, and voltage V_b is measured between 2 and 1, yielding the bend resistance, R_b = V_b/I. The voltage is positive for diffusive transport but becomes negative, if charge carriers move directly from current injecting contact 3 into voltage probe 1 (as shown by the red arrow). b Bend resistance for Dirac fermions in zero B (device D2 with W = 4 μm and θ ≈ 0°). Inset: R_b(B) taken at the minimum indicated by the arrow in the main plot. c Map R_b(V_g,B) for the same device. B was changed in steps of 50 mT. Pockets of negative R_b appear along ϕ/ϕ₀ = 1/q and are seen in magenta. d Cross-sections from (c) for q = 2 and 3. The inset shows sign reversals in R_b plotted as a function of B_eff = B – B_p/q for the minima marked by the color-coded arrows. T = 2 K for all the plots.