Fig. 2: 90^∘-twist resistance anisotropy.

a Four-point resistances measured in Sample O1 at 290 K (H = 0 T) with the current directed in the x–y (a–b) plane. Each panel is identified by the source and drain current contacts (ij) according to the corner-labeling scheme shown in the upper-left panel. For each I_ij, the voltage drop along every other parallel edge, V_kl, is measured and the resulting R_ij,kl = V_kl/I_ij is recorded in Ohms. The length and color of the arrows represent the magnitude of the resistance and the agreement with the isotropic equivalent, respectively. The blue arrows match the isotropic-equivalent values whereas the red arrows indicate R_ij,kl that are anomalously large. The isotropic-equivalent values are given in parenthesis. When the current is directed along a high-conductance axis (upper = \(\hat{{{{{{{{\bf{y}}}}}}}}}\), lower = \(\hat{{{{{{{{\bf{x}}}}}}}}}\)), all of the resulting R_ij,kl agree with the isotropic equivalent (blue arrows). b When the current is directed along the 1-μm-wide z-axis edges, a highly distorted electrical potential landscape arises. The expected values in the isotropic equivalent are all ≃10⁻⁷ Ω. Thus, the red arrows correspond to resistances that are anomalously large by 6 orders of magnitude. The blue arrows indicate near-zero resistance. Vanishing of the potential difference across the vertical edge (e.g. 33′) diametrically opposite to the current contacts (11') is consistent with the C₄I symmetry inherent to the 90° twist (Eq. (2)).